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                  <text>��Perspectivas Sociales - Social Perspectives
Vol. 9, no. 1, primavera/spring 2007
Publicación semestral de/ Biannual publication ofthe:
Universidad Autónoma de Nuevo León, MéJ&lt;jco (Ing. José Antonio González Treviño, Rector; MTS.
Graciela Jaime Rodríguez, Directora de la Facultad de Trabajo Social; Dr.Jorge Noel Valero Gil, Director de
la Facultad de Economía); University of Texas at Austin, E.E.U.U. (Dr. Lany R. Faulkner, President; Dr.
Barbara W. White, Dean School ofSocial Work); University ofTexas atArlington, E.E.U.U. {Prof. James D.
Spaniolo, President; Dr. Santos H. Hemández, Dean School of Social Work); University ofTennessee (Dr.
John Petersen, Presiden!; Dr. Karen Sowers, Dean College of Social Work); Universidad Juárez del Estado
de Durango (C.P. Rubén Calderón Luján, Rector; Lic. Ana Maria Alvarez del Castillo González, Directora
de la Facultad de Trabajo Social), Universidad de Colima (M.C. Miguel Angel Aguayo López, Rector; M.C.
Sergio Wong de la Mora, Director de la Facultad de Trabajo Social).
Editores /Editors

México - UANL: Veronika Sieglin (coord.) y Maria Elena Ramos Tovar
México - U. Juárez de Durango: Maria Guadalupe Salas Medina
Estados Unidos/USA -Austin: Lori Holleran y Dennis Poole
Estados Unidos/USA - San Antonio - Cora Le-Doux
Comité Editorial / Editorial Board

Claudia Campillo Toledano (UANL, México), Guillermina Garza Treviño (UANL, México), Dennis T.
Haynes (UT Austin, E.E.U.U.), Lori Holleran (UT Austin, E.E.U.U.), Cora Le-Doux (Our Lady ofthe Lake
University), Raúl Eduardo López Estrada (UANL, México), Maria Elena Ramos Tovar (UANL, México),
Manuel Ribeiro Ferreira (UANL, México), Veronika Sieglin (UANL, México), José Guillermo Zúñiga
(UANL, México)
Comité Científico / Scientific Com.mittee

Socorro Arzaluz (El Colegio de la Frontera Norte, México), April Brayfield (Tulane University), Krista
Brumley (ITESM), Nilsa Burgos (Universidad de Puerto Rico, Puerto Rico), Miguel Ferguson (UT Austin),
Victor García Toro (Universidad de Puerto Rico, Puerto Rico), Nirmal Goswarni, (Texas A&amp;M UniversityKingsville), Dagmar Guardiola (Universidad de Puerto Rico, Puerto Rico), Emilio Hemández Gómez
(Universidad Autónoma de Baja California, México), Maria de la Luz Javiedes Romero (UNAM, México),
Christina Krause (Universidad de Gottingen, Alemania), Gisela Landázurri Benitez (UAM, México), Maria
Cristina Maldonado (Universidad del Valle, Cali, Colombia), Freddy Marinez Navarro (ITESM, México),
Amparo Micolta Leifü (Universidad del Valle, Cali, Colombia), Benito Narváez Tijerina (UANL, México),
Gabriela de L. Pedroza Villarreal (ITESM, México), C~cilia Quaas Femández (Universidad de Valparaíso,
Chile), María Imelda Ramírez (Universidad Nacional de Colombia), Alba Nubia Rodríguez Pizaro
(Universidad del Valle, Cali, Colombia) Flavio Sacco dos Anjos, (Universidad Federal de Pelotas, Brasil),
Verónica Vázquez García (Colegio de Posgraduados, México), Maria Zebadúa (UANL, México)

Editores del actual número/Editors of this number

Jorge Noel Valero Gil y Lourdes Treviño
Comité de redacción

Elisa HemándezAréchiga (UANL, México)
Coordinadora de difusión y distribución

Maria Elena Ramos Tovar (UANL, México): distribución comercial y académica
Claudia Campillo Toledano (UANL, México): distribución académica
Publicación semestral/semestral publication: correo electrónico/email: veronikasieglin@yahoo.de;
vsieglin@hotmail.com; lorikay@mail.utexas.edu; mramor@facts.uanl.mx
www_. fts.uanl.rnx\revista.html
ISSN: 1405-1133
Impreso en /Printed in Monterrey, Nuevo León, México
Primavera de 2007
Tiraje /issue: 1500
Los artículos publicados son responsabilidad exclusiva de los autores / Toe articles published in this joumal
are solely the responsability of the authors

FONDO
UNIVERSITARIO

�Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vo/.9, Num. I I

FONDO

INDICE DE CONTENIDO - TABLE OF CONTENTS UNIVERSITARIO

Presentación - Presentation

5

ARTICULOS DE INVESTIGACIÓN RESEARCB ARTICLES
Has Mexican growth been pro-poor?
Abdelkrim Araar; Jean-Yves Duelos,
Mathieu Audet, Paul Malaiissi

17

Pro-Poor Food Taxation and Subsidy Reforms in Mexico
Mathieu Audet, Paul Makdissi,
Abdelkrim Araar; Jean-Yves Duelos

49

Gender-bias in Education Opportunities for Population
Aged 12-18 in Mexico: 1992-2004
Ernesto Aguayo, Joana Chapa, Erick Rangel,
Lourdes Treviño, Jorge Va/ero

65

Toe Informal Sector in Mexico: Characteristics and Dynamics
Eduardo Rodríguez-Oreggia

89

Access and Use ofHealth Care Services by Mothers and
Children in the Texas-Mexico Border Region: Preliminary
Findings from the 2006 Rio Grande Valley Health Survey
Patricia B. Reagan, José A. Pagán

157

Diabetes and Employment Productivity:
Does Diabetes Management Matter?
H. Shelton Brown IIL José A. Pagán,
Craig Hanis, Adriana Perez

175

�Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vo/.9, Num. I I Pág. 5-14

NORMAS DE PRESENTACIÓN DE ARTÍCULOS GUIDELINES FOR CONTRIBUTORS
FORMATO DE SUSCRIPCIÓN SUBSCRIPTION FORM

5

Presentación

Este número especial contiene seis de los artículos presentados en el
"VID Encuentro Internacional de Capital Humano, Crecimiento, Pobreza:
Problemática Mexicana" que fue llevado a cabo en Octubre de 2006 en
Monterrey, México. Cuatro de los artículos versan sobre la problemática
de México y los restantes dos sobre la región localizada en la frontera
Estados Unidos-México en Texas que se caracteriza por altos niveles
de pobreza y una alta proporción de población hispánica. Los artículos
tratan de pobreza, impuestos y pobreza, salud y pobreza, los sectores
formal e informal y la discriminación en educación.
Los artículos "Has Mexican growth been Pro-poor?" y "Pro-Poor
Food Taxation and Subsidy Reforms in Mexico" aplican nuevas técnicas
para estudiar la pobreza en México. El primer artículo trata los cambios en pobreza entre 1992, 1998 y 2004 y utiliza datos de la ENIGH
(Encuenta Nacional de Ingreso Gasto de los Hogares) y el segundo trata
los efectos de impuestos potenciales en alimentos como cereales, leche,
carne, pescado, huevos, aceites, tubérculos, verduras, frutas, azúcar y café
utilizando la ENIGH 2004. La técnica del artículo sobre crecimiento
se deriva de Duelos y Wodon (2004) y la del artículo sobre impuestos
en alimentos se deriva de Makdissi y Richard (2007). Ambos artículos
definen funciones de evaluación para hacer el análisis de cambio distribucional. Ambos definen una norma relativa y absoluta para trabajar en
pobreza. La norma relativa del artículo sobre crecimiento evalúa si el
ingreso representativo de los pobres crece más aprisa que el crecimiento
promedio del ingreso y la del artículo sobre impuestos en alimentos se
enfoca en el consumo relativo de los pobres respecto al ingreso relativo.
La norma absoluta del artículo sobre crecimiento representa el cambio
absoluto en el ingreso de los pobres, mientras que la del artículo sobre
impuestos en alimentos considera el consumo de los pobres en cada
alimento contra el consumo promedio. Ambos artículos confrontan el
problema de que México tiene dos líneas de pobreza: una para las áreas
ISSN 1405-1133 O 2007 Universidad Autónoma de Nuevo León, University ofTexas of Austin,
University ofTexas ofArlington, University ofTennessee,
Universidad Juárez del Estado de Durango, Universidad de Colima.

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/ Presentación / Presenta/ion

rurales (menos de 15000 habitantes) y otra para las áreas urbanas, determinando los ingresos en referencia a los precios rurales.
El artículo sobre crecimiento desarrolla las herramientas estadísticas
para probar la signi:ficancia de los resultados. Los autores encuentran
que el crecimiento de México fue totalmente anti-pobre (de acuerdo a la
norma absoluta) durante el periodo 1992-1998 y pro-pobre durante los
periodos 1998-2004 y 1992-2004. Estos resultados aplican tanto para
la razón de pobreza (headcount ratio) como para los índices diferenciales de pobreza promedio. Las pruebas de la pro-pobreza relativa entre
1998 y 2004 y entre 1992 y 2004 son concluyentes en el sentido de que
el crecimiento en estos periodos fue pro-pobre tanto para la razón de
pobreza como para los índices diferenciales.
El artículo sobre impuestos a los alimentos determina el impacto
de cambios marginales en el impuesto a un bien al nivel de pobreza de
un individuo dado un nivel de ingreso. Los autores definen las curvas
Dominancia de Consumo pro-pobreza, relativas y absolutas, siguiendo a
Makdissi y Richard (2007) y encuentran resultados diferentes para estas
medidas. En el caso de las medidas relativas encuentran que la reducción
marginal en impuestos en cualquiera de los alimentos estudiados sería
pro-pobre. Cuando se utiliza la norma absoluta, este resultado se obtiene
solamente para los impuestos en aceites, azúcar y huevos. Incrementos
marginales en cualquier impuesto al consumo de cualquier otro de los
alimentos sería totalmente pro-pobre.

1
1

La distribución de recursos dentro del hogar se ha vuelto uno de
los aspectos más importantes en la investigación del capital humano.
Existe considerable evidencia de que los recursos no son distribuidos
aleatoriamente dentro de los hogares y que además son distribuidos
inequitativamente en muchos países en desarrollo. El artículo "Genderbias in Education Opportunities for Population Aged 12-18 in Mexico:
1992-2004" estudia la existencia de discriminación en educación en
México en contra de mujeres jóvenes.
Para el caso de México, se piensa generalmente que las niñas - más
específicamente las niñas pobres de áreas rurales- son discriminadas en
educación dentro de sus familias. También se cree que 15 de cada 100

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Yol.9, Num. 1 I

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padres no invierte en la educación de sus hijas porque piensan que las
niñas se casarán y, por lo tanto, invertir en su educación seria un desperdicio de dinero. Más aún, los esfuerzos gubernamentales para abatir la
pobreza se han enfocado recientemente en disminuir la "supuesta" discriminación contra las hijas. El programa de asistencia social Oportunidades (antes Progresa) entrega apoyos monetarios a las familias pobres
con la condición de que los hijos asistan a la escuela y a los centros de
salud. Con la intención de disminuir la supuesta discriminación contra
las mujeres, las transferencias son mayores para las niñas que para los
niños. Los autores no encuentran suficiente evidencia para apoyar tales
creencias. Utilizando un modelo de Mínimos Cuadrados Ordinarios
robustos y un efecto de Máxima Verosimilitud con efectos aleatorios para
los años 1992, 1998 y 2004, no encuentran suficiente evidencia estadística
para apoyar la idea de que las familias pobres, ni en zonas rurales ni en
zonas urbanas, dan mayor educación a sus hijos que a sus hijas de 12
a 18 años, o viceversa. De hecho, contrario a la creencia común, los
autores encuentran que las familias no pobres, según La definición del
Comité Técnico de Medición de La Pobreza (2002), invierten más en la
educación de sus hijas que de sus hijos.
EL artículo "The comparative dynamics of the informal sector in
Mexico" contiene tres partes. En las primeras dos se comparan tres
periodos de tiempo: 1990-1991, 1995-1996 y 2003-2004 y en la tercera
se comparan los años 1991, 1996 y 2004. Los datos utilizados son de la
Encuesta Nacional de Empleo Urbano (ENEU) y la sección urbana de
la Encuesta Nacional de Empleo Trimestral (ENET) ya que los hogares
encuestados en ambas bases de datos son seguidos durante cinco trimestres.
En la primera parte, el autor utiliza matrices de transición para estudiar los cambios entre las siguientes ocho categorías laborales: informal
dependiente, formal dependiente, empleador, autoempleado, sector
público, no remunerado e inactivo. En esta parte se encuentra que las
principales opciones para las mujeres, tanto en el sector formal como el
informal, son permanecer en el mismo status (categoría) o cambiar a la
inactividad. Para los hombres dentro del sector formal o informal, las
opciones más importantes son permanecer en el mismo sector o cambiar de un sector al otro. En la segunda parte, el autor utiliza el modelo

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Revista Perspectivas Socia/es / Social Perspectives primavera/spring 2007. Vo/.9, Num. I /

logístico donde las variables dependientes son las diferentes categorías
laborales. Se encuentra que una mayor edad disminuye la probabilidad de
estar en el sector formal y que la gente más educada tiene mayor probabilidad de estar en el sector formal o en el sector público. Otro hallazgo
importante es que la probabilidad de tener seguridad social aumenta si
otros miembros del hogar también tienen este beneficio. Finalmente, en
la tercera parte, se utilizan regresiones cuantílicas para determinar los
salarios y las categorías laborales. El autor encuentra que las categorías
empleador y sector público presentan los rendimientos más altos.
El artículo "Access and Use of Health Care Services by Mothers
and Children in the Texas-Mexico Border Region: Preliminary Findings
from the 2006 Rio Grande Valley Health Survey" de Reagan y Pagán
reporta resultados sobre la relación entre los patrones de uso de servicios
de salud de las madres que viven en la frontera Estados Unidos-México y
sus hijos, utilizando la Encuesta de Salud del Valle de Río Grande 2006
la cual reúne datos sobre madres y un hijo de cada hogar seleccionado
aleatoriamente siempre que sean residentes de los condados de Cameron
Hidalgo, Start y Willacy. Las comunidades a lo largo de esta fronter;
se encuentran entre las de las tasas de pobreza y falta de aseguramiento
médico más altas en Estados Unidos. Las estimaciones son realizadas
en dos pasos. En el primero, se estiman los determinantes de acceso/uso
a los servicios de salud tanto para madres como para sus hijos utilizando
años de edad, género, status de salud (reportado por el encuestado), ingreso familiar anual y status de aseguramiento médico en un modelo de
ecuaciones probit bivariadas. En el segundo paso se encuentra que los
errores de ambas estimaciones, para madres e hijos, están relacionados.
Este resultado es importante ya que muestra que las intervenciones que
promueven el buen uso del servicio de salud para madres latinas tienen
efectos positivos sobre sus hijos. Los autores argumentan que los programas públicos de seguridad social que se enfocan en cubrir a los hijos
que no están asegurados, pero que dejan a los padres sin seguro pueden
no tener la ventaja de presentar estos efectos que pasan de madres a
hijos.
El artículo "Diabetes and Employment Productivity: Does Diabetes Management Matter?" de Brown, Pagán, Hanis y Pérez utiliza
información de una encuesta llevada a cabo en Brownsville Texas en

'

'

9

un área metropolitana que está localizada en la región fronteriza entre
Estados Unidos y México que se caracteriza por altos niveles de pobreza,
bajo desempeño en educación y por un 91.3% de población de origen
hispánico. Los autores utilizan microdatos del Proyecto de Impacto en
Diabetes y seleccionaron un participante de cada hogar. El artículo tiene
dos secciones principales. En la primera sección, los autores examinan
si un pobre ~ontrol de la diabetes, medido por la interacción de tener
diabetes y niveles de hemoglobina glicosilada Hbalc, es la causa de
resultados adversos en el mercado de trabajo más que estos resultados
fueran causados solamente por presentar la enfermedad. En la segunda
sección, los autores examinan si la diabetes afecta o no en la productividad laboral entre niveles de salarios, con o sin control, mediante una
regresión cuantílica. En la primera parte los autores encuentran que, en
el caso de hombres con diabetes, la enfermedad per se está negativamente
relacionada a los salarios. En la segunda parte encuentran que los efectos
nocivos de la diabetes son mayores en los deciles más altos de ingreso y
que aquellas personas con diabetes controlada no son más productivas
que quienes la presentan y no la han controlado.

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/ Presentación I Presenta/ion

Presentation

This special issue contains six of the papers presented at the "VIII International Meeting of Human Capital, Growth, Poverty: Mexican Problematic" that took place in Monterrey, Mexico in October 2006. Four
of the papers are about Mexico and the remaining two about the region
located in the US-Mexico border in Texas, which is characterized by
high levels ofpoverty anda high proportion ofHispanic population. Toe
papers &lt;leal with poverty, taxes and poverty, health and poverty, formal
and informal labor sectors and discrimination in education.
Toe papers "Has Mexican growth been pro-poor?" and "Pro-Poor
Food Taxation and Subsidy Refonns in Mexico" apply new techniques
to study poverty in Mexico. Toe first paper is related to the changes in
poverty among 1992, 1998 and 2004 and uses data from ENIGH (National Survey ofHousehold Income and Expenditures). The second one
is related to the e:ffects of potential taxes on foods such as cereals, milk,
meat, :fish, eggs, oils, tubercles, vegetables, fruits, sugar and coffee using ENIGH 2004. Toe technique of the paper on growth is derived from
Duelos and Wodon (2004) and the one of the paper on taxes on foods is
derived from Makdissi and Richard (2007). Both papers define evaluation
functions to make the analysis of distributional change. Moreover, both
define a relative and an absolute norm to work on poverty. Toe relative
nonn of the paper on growth evaluates if the representative income of
the poor grows faster than the mean growth of income, while the paper
on taxes on foods looks at the relative consumption of the poor against
the relative income. Toe absolute norm of the paper on growth represents
the absolute change in the poor's income, whereas the paper on taxes on
foods considers the consumption of the poor on each good against the
average consumption. Both papers confront the problem that Mexico
has two poverty lines: one for the rural areas (less than 15000 habitants)
and one for urban areas by assessing ali income measures in reference
to rural prices.
Toe paper on growth develops the statistical tools to test for the
significance of the results. Toe authors find that Mexico's growth was

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Vo/.9, Num. l /

11

absolutely (with absolute nonn) anti-poor during the period 1992-1998
and pro-poor during the periods 1998-2004 and 1992-2004. These results apply to the headcount ratio as well as to the average poverty gap
indices. Toe tests for the relative pro-poomess between 1998 and 2004
and between 1992 and 2004 are conclusive in the sense that the growth
in these periods was pro-poor for both measures of poverty.
Toe paper on pro-poor food taxation assesses the impact ofmarginal
changes to the tax on a good at the poverty leve! of an individual, given
a certain level of income. Toe authors define the relative and absolute
pro-poor Consumption Dominance curves following Makdissi and Richard (2007) and they find different results for these measurements. In the
case of the relative measurements, they observe that marginal reduction
in taxes on any category of the foods studied would be pro-poor. When
the absolute norm is used, this result is only obtained for the taxes on
oils, sugar and eggs. Marginal increases in any consumption tax on any
other category of foods would be absolutely pro-poor.
Toe intra-household allocation ofresources has become one ofthe
most important issues in human capital research. There is considerable
evidence that resources are not only allocated randomly within households, but also unequally distributed within the family in many developing countries. The paper "Gender-bias in Education Opportunities for
Population Aged 12-18 in Mexico: 1992-2004" studies the existence
of discrimination in Mexico against young women related to years of
education.
For the case ofMexico, it is generally believed that girls-more speci:fically poor rural girls- are educationally discriminated within their
families. It is also claimed that 15 of every 100 parents do not invest the
education of their daughters because they think girls will in get married
and, therefore, investing in their education woulol be a waste of money.
Furthermore, government efforts to abate poverty have been recently
focused on decreasing the "assumed" discrimination against female
children. Toe government assistance program Oportunidades (formerly
Progresa) gives monetary transfers to poor families conditioned on ~aving their children attending school and health clinics. Intended to reduce
such "assumed" discrimination against girls, transfers are larger for girls

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/ Presentación / Presenta/ion

than for boys. Toe authors &lt;lid not find enough evidence to support such
believes. Using an OLS-Robust model anda ML-Random Effects model
for the years 1992, 1998 and 2004, they did not find enough statistical evidence to support the idea that poor families, either in rural as in
urban areas, provide more education to their 12 to 18 years old sons or
daughters. In fact, contrary to the general belief, they found that non-poor
families, as established by the Mexican Technical Committee for Measuring Poverty (2002), invest more in the education oftheir daughters.
The paper "Toe comparative dynamics of the informal sector in
Mexico" is divided into three parts. The first two compare three time
periods: 1990-1991, 1995-1996 and 2003-2004 and the third part compares the years 1991, 1996 and 2004. Toe data come from the ENEU
(National Survey ofUrban Employment) and the urban part ofthe ENET
(Quarterly National Survey of Employment), since in those surveys the
households are followed through five quarters.
In the first part the author uses transition matrices to study the changes
among the following eight work status: dependent informal, dependent
' formal, employer, self-employed, public sector, not remunerated, unemployed and inactive. It is found that the main options for women working
in the formal and informal sectors are to remain in the same status or to
move to inactivity. Formen employed in the formal or informal sector,
the most important options are to remain in the same sector orto switch
from one sector to the other. In the second part, the author utilizes the
multinomial logit model having as dependent variables the different
work status. He finds that a higher age lowers the probability of being
employed in the formal sector and that more educated people have higher
probability of being employed in the formal e r public sectors. Another
important finding is that the probability of havir;g social security increases
if other members of the household also have this benefit. Finally, in the
third, quantile regressions are used to study the determinants of wages
and the work status. Toe author finds that thi&gt; c;tatus of employer and
public sector show the highest returns.
The paper "Access and Use ofHealth Care Services by Mothers and
Children in the Texas-Mexico Border Region: Preliminary Findings from
the 2006 Rio Grande Valley Health Survey" ofReagan and Pagan reports

Revista Perspectivas Sociales I Socio/ Perspectives primavera/spring 2007. Vol. 9, Num. 1 I

13

results on the pattems ofhealth care utilization between border-dwelling
mothers and their children, using the 2006 Rio Grande Valley Health
Survey, which collects data on mothers and one randomly selected child
from each household, residing in Cameron, Hidalgo, Start and Willacy
counties. Communities along this U.S. - Mexico border region have the
highest rates of poverty and uninsurance in the U.S. Toe estimations
are made in two steps. In the first one the determinants of health care
access/utilization are estimated for both mothers and children utilizing
years ofage, gender, self-reported health status, yearly household income
and health insurance status, in a model of bivariate probit equations. In
the second step, the errors of both regressions, mothers and children,
are found to be related. This result is important because it shows that
interventions that promote good health care utilization behavior for Latín
mothers spillover to their children. The authors argue that public health
insurance programs that focus on covering uninsured children but leave
their parents uninsured may end up not taking full advantage of health
care access/utilization from mothers to their children.
The paper "Diabetes and Employment Productivity: Does Diabetes
Management Matter?" of Brown, Pagan, Hanis and Perez uses information from a survey in Brownsville, Texas, a metropolitan area that is
located in the US-Mexico border region characterized by high poverty
levels; low educational attainment and by a 91.3% of Hispanic origin
population. Toe authors used microdata from the Diabetes hnpact Project
and selected one participant from each household. The paper is organized
in two sections. In the first one, the authors examine whether poor diabetes management, measured by the interaction ofhaving diabetes and
glycosylated hemoglobin levels (Hbalc), is the cause of adverse labour
market outcomes rather than diabetes per se. In the second one, they
examine whether or not diabetes a:ffects labour productivity, whether
managed or not, across wage levels using quantile regression. In the first
part the authors find that in the case of men diabetes per se is negatively
related to wage. In the second part they find that the detrimental e:ffects
of diabetes are higher at the higher wage quantiles and that those persons
with diabetes who do manage it are not more productive than those whose
diabetes has not been managed.

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Duelos, J.-Y. and Q. Wodon (2004): "What is "Pro-Poor"?" CIRPEÉ
Work.ing Paper #0425.
Makdissi, P. and P. Richard (2007), "Pro-Poor Indirect Tax Reforms",
mimeo.

ARTÍCULOS
DE INVESTIGACIÓN RESEARCH ARTICLES

�Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Vol.9, Num. 1I Pág. 17-47

17

Has Mexican growth been pro-poor?
Abdelkrim Araar*, Jean-Yves Duclost,
Mathieu Audet¡, Paul Makdissi§
**

Abstract
This paper propases techniques to test for whether growth has been propoor. We first review different definitions of pro-poomess and argue for
the use of methods that can generate results that are robust over classes
of pro-poor measures and ranges of poverty lines. We then provide
statistical pro-cedures that rely on the use of sample data to infer whether
growth has been pro-poor in a population. We apply these procedures to
Mexican household surveys for the years of 1992, 1998 and 2004. We
find strong statistical evidence that Mexican growth has been absolutely
anti-poor between 1992 and 1998, absolutely pro-poor between 1998
and 2004 and between 1992 and 2004, and relatively pro-poor between
1992 and 2004 and between 1998 and 2004. Toe relative assessment of
the period between 1992 and 1998 is statistically too weak to lead to a
robust evaluation of that period.

Keywords
Pro-poor growth, Poverty, lnequality.

* Département d' économique and CIRPÉE, Pavil/on De S 'eve, Université lava[,
Sainte-Foy, Québec, Ganada, GJK 7P4; emai/: aabd@ecn.ulaval.ca; fax: /-418-6567798;
f Département d' économique and CIRPÉE, Pavillon de S 'eve, Université lava/, Qu
ébec, Ganada, GIK 7P4; email: jyves@ecn.ulaval.ca; fax: /-418-656-7798; phone:
1-418-656-7096
f GRÉDL Université de Sherbrooke, 2500, boulevard de l'Université, Sherbrooke, Qu
ébec, Ganada, J/K 2RI; email: maudet@worldbank.org
§ Département d'économique and CIRPÉE, Université de Sherbrooke, 2500 boulevard
de l'Université, Sherbrooke, Québec, Ganada, JIK 2RI; emai/: paul.makdissi@USherbrooke.ca
** We are grateful to Dr. Lourdes Treviño and Professor Jorge Va/ero Gilfor their invita/ion to present this paper al the Eight Symposium on "Capital Humano, Crecimiento,
Pobreza: Problemática Mexicana" that took place in Monterrey, Mexico on October 12
and 13, 2006, and to the participants at that conference for valuable comments.
ISSN 1405-1133 O 2007 Universidad Autónoma de Nuevo León, University ofTexas ofAustin,
Univer.aity ofTexas of Arlingtoo, Uoiv=ity ofTeonessee,
Universidad Juárez del Estado de Durango, Universidad de Colima

�18

/ Has Mexican growth been pro-poor?

Resumen
Este trabajo propone técnicas para comprobar si el crecimiento ha sido a
favor de los pobres. Primero repasamos las diferentes definiciones a favor
de la pobreza o "pro pobres" y argumentamos por el uso de métodos que
puedan generar resultados que sean robustos eligiendo entre clases de
mediciones pro pobreza y rangos de lineas de pobreza. Luego generamos
procedimientos estadísticos que se basen en datos muestrales y que
permitan inferir si el crecimiento ha sido pro pobreza en una población.
Aplicamos esos procedimientos a muestras de hogares mexicanos para
los años 1992, 1998 y 2004. Encontramos fuerte evidencia estadística de
que el crecimiento mexicano fue absolutamente anti pro pobreza entre
1992 y 1998, absolutamente pro pobreza entre 1998 y 2004 y entre 1992
y 2004, y relativamente pro pobreza entre 1992 y 2004 y entre 1998 y
2004. La evaluación de la medida relativa en el período entre 1992 y
1998 es muy débil estadísticamente para que conduzca a una evaluación
robusta del período.

Palabras clave
Crecimiento pro pobres, pobreza, desigualdad.

Introduction
It would seem relatively uncontroversial to conceive of the pro-poomess
of growth as referring generally speaking to the impact ofgrowth on the
wellbeing of the poor and therefore to its impact on poverty. Like many
distributive concepts, however, its precise meaning and its usefulness are
essentially a matter of judgement1 • There are at least three elements of
contention in trying to make the assessment ofpro-poomess operational.
Toe first fundamental issue in the definition of pro-poomess is whether
it should be absolute or relative. A second issue is what poverty line
should be chosen to separate the poor from the non-poor. A final issue
is how we should assess in the aggregate the heterogeneous impact of
growth among a population of heterogeneous poor, an issue which also
addresses what relative normative weights are to be attributed to the
different poor individuals.
1 See, among many recen! contributions to that debate, Bourguignon (2003), Bruno,
Raval/ion, and Squire (1999), Do/lar and Kraay (2002), Eastwood and Lipton (2001),
United-Nations (2000), and World-Bank (2000).

Revista Perspectivos Sociales / Social Perspeclives primavera/spring 2007. Vo/.9, Num. l I

19

This paper attempts to address all these three issues and to make it
conceptually operational and empirically feasible to test for the pro-poorness of distributive changes. To do this, we first rely on the definitional
framework of Duelos and Wodon (2004). Roughly speaking, and according to that framework, a relative definition of pro-poomess judges
a distributive change to be pro-poor if the proportional change in the
incomes of the poor is no less than sorne norm, often set as the growth
rate in mean income or in sorne quantile such as median income. For an
absolute definition, the incomes of the poor need to grow by an absolute
amount that is no less than sorne norm, this time often set as zero or as
sorne proportion of the absolute change in mean or median incomes.
These different definitions can also be linked to the usual concepts of
absolute and relative poverty. With relative poverty, the poverty line is
usually defined as a proportion of sorne central tendency of an income
distribution; with absolute poverty, the real level of the poverty line
normally remains the same even if the income distribution changes.
Toe framework of Duelos and Wodon (2004) also enables to get
around the difficult of having to choose l) a poverty line to separate the
poor from the nonpoor, and 2) a set ofnormative weights to differentiate
among the poor. Toe framework &lt;loes this by investigating how pro-poor
judgements can be made robust to wide classes of pro-poor evaluation
functions and to ranges of poverty lines.2
This paper then makes it empirically feasible to test for pro-poomess
of growth. To do this, we derive the sampling distribution of the various
estimators that are needed to test for absolute and relative pro-poomess.
This enables us inter alia to draw confidence intervals around the differences that must be signed in order to conelude that a change has been
robustly pro-poor - or not. We implement these statistical techniques
taking full account of the sampling design of the surveys we use. We
apply the procedures to Mexico's National lncome and Expenditure
Surveys collected in 1992, 1998 and 2004. We find strong evidence that
2 Many di.fferent approaches have been proposed to separate the poor from the nonpoor and to compute and aggregate index ofpro-poorness. See.for instance, McCul/och
and Baulch (1999), Kakwani, Khandker, and Son (2003), Kakwani and Pernia (2000),
Raval/ion and Chen (2003), Klasen (2003), Essama-Nssah (2005), Rava/lion and Datt
(2002) and Son (2004).

�20

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Has Mexican growth been pro-poor?

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2()()7. Vol. 9, Num. 11

Mexican growth has been absolutely anti-poor between 1992 and 1998,
absolutely pro-poor between 1998 and 2004 and between 1992 and 2004
and relatively pro-poor between 1992 and 2004 and between 1998 and'
2004. The relative pro-poor assessment of the period between 1992 and
1998 is, however, statistically too weak to lead to a robust pro-poor
evaluation of that period.

Theoretical framework

The setting
Let y, = (yf ,Y~ , · · · , Y!J E~• be a vector of non-negative initial incomes3
(at time 1) of size n 1, and let y2 = (!A, Yi. ··· ,iln.) be an analogous vector
of posterior incomes (at time 2) of size n2•

,.,

21

Toe change from yl to y2 will be deemed pro-poor if W (y, Y2, g, z) :SO.
Clearly, whether the distributional change will be deemed pro-poor
will depend on the way in which z , IT, and IT* will be chosen. To put
sorne structure on the form of W in which we should be interested, we
need to invoke a few axioms. Toe first one is a focus axiom: W is not
sensitive to the values of y 1 that exceed z . Toe distribution of min(y; ,
z ) is thus sufficient for judgements of pro-poomess.
Second, we can postulate an axiom of population invariance. This
says that adding a replication of a population to that same population has
no impact on W. lt is a common axiom in welfare economics that enables
us to make pro-poor judgements even when the absolute population size
varies across the distributions.

The following draws extensively from Duelos and Wodon (2004).
To determine whether the movement from y I to y2 is pro-poor, we :first
need to define a standard with which this assessment can be made. First
consider the case of a relative standard, which we will take in this paper
as the growth in average incomes, denoted by g. Intuitively, for growth
to be relatively pro-poor, we wish the poor's "representative" income to
undergo a proportional change that is no less than 1+g. That growth g
can be negative as well as positive. Relative pro-poomess is consistent,
for instance, with the view ofKakwani and Pernia (2000) that "promoting
pro-poor growth requires a strategy that is deliberately biased in favor
of the poor so that the poor benefit proportionately more than the rich.
(p.3)".

A third axiom is that of anonymity: this says permuting the incomes
of any two persons in any given distribution should not affect pro-poor
judgements. Note that this axiom will typically lead to violations of the
well-known Pareto effi.ciency criterion; our framework does not not
require that none ofthe poor be penalized by a distributional change for
that change to have a chance to be declared pro-poor. Were we not to
impose this axiom, it would be practically impossible to order the initial
and posterior distributions in the presence of a large number of individuals, and we would also need panel data.

Toen denote by z &gt; Oa poverty line, defined in real terms. Let W
(yi, Y2, g, z) be the pro-poor evaluation function that we want to use. It
is defined as the difference between two evaluation functions TI (y1 , z)
and TI* (Y2 , 1 + g, z), each for time 1 and time 2, respectively, and which
are analogous to poverty indices for each of the two time periods:

We may then also impose an axiom of monotonicity: for a given g,
if anyone's posterior income increases, W should not increase, and may
sometimes fall. Increasing posterior incomes make it more likely that
the distributive change will be declared pro-poor.

Toe next axiom is a normalization one: if there has been no distributional change, and thus also no change in the mean, then W = O.

Relative pro-poor judgements

W (Y1, Y2, g, z) = (Y2, 1 + g, z )3

IT (y1, z).

Or consumption, wealth, or any other welfare indicator ofinterest.

(1)

Finally, we can also axiomatize our view of relative pro-poomess. Formally, suppose that y/ (l + g) = y/ (1 + g). Toen, according to relative
judgements ofpro-poomess, y and y should be judged equally pro-poor

�22

/ Has Mexican growth been pro-poor?

Revista Perspectivas Sociales / Social Perspectives prim&lt;Neralspring 2007. Vol.9, Num. I I

by W regardless of the initial distribution y 1 •
Combined together, the axioms that we have invoked until now
define what we can term to be a first-order class of relative pro-poor
evaluation functions. Denote that class as Q 1 (g, z +). The class Q 1 (g, z
+) regroups all of the functions W that satisfy the focus, the population
invariance, the anonymity, the monotonicity, the normalization and the
relative axioms, and for which z '.S z + .
Now let Fj (y) be the distribution function of distributionj. Also
define as Qj (p) the quantile function for distribution Fj . This is formally
defined as Qj (p) = inf {s?: O¡Fj (s)?:p} forp E (O, l]. With acontinuous
distribution and a strictly positive income density, Q(p) is simply the
inverse ofthe distribution function, and it is the income of that individual
who is at rank p in the distribution.
The popular class of FGT indices is then given by:
P,(z)

1

.P¡(z;a) =

(1- Q,(p)/z)º dp.

(2)

0

Pj (z; a= O) is the headcount index (and the distribution function) atz,
and Pj (z ; a = 1) is the average poverty gap. Duelos and Wodon (2004)
show that a movement from y 1 to y2 will be judged pro-poor by ali propoor evaluation functions W ( ·, ·, g, z ) that are members of Q 1 (g, z +)
if and only if
(3)

A distributional change that satisfies (3) is called first-order relatively
pro-poor since all pro-poor evaluation functions within Ql (g, z +) will
find that it is pro-poor, and this, for aoy choice of poverty line within
(O, z +] aod any W that obeys the above-defined axioms. Verifying (3)
simply involves checking whether - over the range of poverty lines [O,
z +] - the headcount index in the initial distribution is larger than the
headcount index in the posterior distribution when that distribution is
normalized by l + g.

An altemative and equivaleot way of checking whether a distribu-

23

tional change can be declared fust-order relatively pro-poor is to compare
the ratio ofthe quantiles to the ratio of the mean, or again equivalently,
to compare the growth in quantiles to the growth in the mean. That this,
we check whether, for allp E [O, Fl (z +)],

(4)
or whether
Q2(p)- Q¡(p) &gt;
Q1(p)
- g.

(5)

Using (5) is equivalent to Ravallion and Chen (2003)'s suggestion to use
"growth incidence curves" to check whether growth is pro-poor. These
curves show the growth rates of living standards at different ranks in
the population.
First-order pro-poor judgements can be demanding in expansion
periods. They require ali quantiles of the poor to undergo arate of growth
at least as large as the rate of growth in mean income. We may, however,
be willing to relax this condition if the rate of growth for the poorer
among the poor is sufficiently large to exceed g even though the rate of
growth for the not-so-poor may be below g. An axiom that captures this
is the distribution sensitivity axiom. It says that the evaluation functions
TI should give more weight to the poorer than to the not-so-poor among
the poor. Distribution-sensitive pro-poor judgements imply that shifting
incomes from the richer to the poorer is by itself a pro-poor distributional
change. This axiom is known as the Pigou-Dalton principie in the welfare
literature.
Adding the distribution-sensitive axiom to the earlier axioms defines
a second-order class of relative pro-poor evaluation functions Q2 (g, z+).
Formally, Q2 (g, z +) is made of all functions W (·, ·, g, z) that satisfy the
focus, the population invariance, the anonymity, the monotonicity, the
normalization, the distribution sensitivity and the relative axioms, and
for which z:::; z +.

It can then be shown that a movement from yl to y2 will be judged propoor by all pro-poor evaluation functions W (, , g, z ) that are members

�24

/

Has Mexican growth been pro-poor?

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Vol.9, Num. 1/

of Q2 (g, z +) if and only if
A ((1+ g)z;a = 1) $ Pi (z; o: = 1) forall z E (o,z+¡.

(6)

As for (3), a distributional change that satisfies (6) is called second-order
relatively pro-poor since all pro-poor evaluation functions will find that
it is pro-poor, and this, for any choice of poverty line within [O, z +]
and for any W that obeys the above-mentioned axioms for Q2 (g, z +).
Verifying (6) simply involves checking whether the average poverty gap
in the initial distribution is larger than that in the posterior distribution
when that distribution is normalized by 1+ g and this, over the range of
poverty lines [O, z +].
As for first-order pro-poor judgements, there are alternative ways
of checking condition (6). The cumulative income up to rank p (the
Generalized Lorenz curve at p) is given by
C;(J¡) = [ Q;(q)dq.

(7)

Toe use of the Generalized Lorenz curve provides an intuitive sufficient
condition for checking second-order relative pro-poorness. A distributiona~hange is indeed second-order relatively pro-poor if for all
p E [O, F2 (z + )],

1 ,,

(8)

11

o

Expression (8) involves computing the growth rates in the cumulative
incomes of proportions p of the poorest, and to compare those growth
rates to g. For 1 + g equal to the ratio of mean income, condition (8) is
equivalent to checking whether the Lorenz curve for y2 is above that of
y 1 for the range ofp E [O, F2 ((1 + g)z + )].

Absolute pro-poor judgements
Absolute pro-poor judgements are made by comparing the absolute
change in the poor's incomes to sorne absolute pro-poor standard.
Denote that standard as a. Toe axiom of absolute pro-poomess says

25

essentially that TI* should be "translation invariant" in y and a, or that
the pro-poor judgement should be neutral whenever the poor gain in
absolute terms the same as the standard a. Hence, this axiom demands
that if y + a :: y, then W (y, y, ~ z) :: O. This allows us to _define the
class of first-order absolute pro-poor evaluation functions QI (a, z +)
as made of ali those functions W ( ·, ·, a, z ) which satisfy the focus, the
population, the anonymity, the monotonicity, the normalization and the
absoluteness axioms, and for which z S z + . We will later set a to zero
for the empirical illustration of this
paper.
We can then show that a movement from yl to y2 will be judged
first-order absolutely pro-poor (that is, P!O-poor by all evaluation functions W ( , , a, z) that are members of Ql (a, z +)) if and only if
(9)

An equivalent way of checking whether a distributional change can be
declared first-order absolutely pro-poor is to compare the absolute change
in the values of the quantiles for ali p E [O, F(z + )]:
(10)
An analogous result holds for absolute second-order pro-poor judgements.These judgements also obey the axiom of distribution sensitivity:
they are made on the basis of the class of indices Q 2 ( a, z +), which is
defined as for QL (a, z +) but with the additional requirement of distribution sensitivity. We can then show that a movement from y 1 to Y2 will
be judged second-order absolutely pro-poor if and only if
(z +a)A((z+ a;a = 1) $ zP1 (z; a = 1) for ali z E [o,z+].

(11)

A sufficient condition for condition (11) is then to verify whether, for ali
p E [O, F2 (z ++a)], the change in the average income of the bottom p
proportion of the population is larger than a:
(12)

�26-

/

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Yol.9, Num. 11

Has Mexican growth been pro-poor?

Statistical inference
In practice, household data surveys are needed to check if growth is
pro-poor or not. This forces us to &lt;leal with issues of sampling variability and statistical inference. Indeed, a difference observed in a sample
may not be empirically strong enough to be significant from a statistical
point of view4 .
Each of the conditions noted above takes the form of testing whether
N (z) :'.SO or !).s (p) ~ Oover sorne range ofz or p. This therefore involves
testingjointly overa set of null hypotheses. For primal tests ofpro-poorness, our formulation of our null hypothesis is thus that of a union of
null hypotheses
H0 : t.'(z) &gt; Oforsome zE (o,z+]
(13)

27

per can be shown to be asymptotically normally distributed, we can use
~ (z)+uA•&lt;•&gt;((B)as altemative lower and upper bounds for one-sided confidence intervals for !).s (z). For instance, an upper-bounded confidence
interval ~ (z)+uA•&lt;.-&gt;((8~ shows all of the values of r,. for which we could
not reject a null hypothesis Ho :t.•(z) ::=; r,.in favor of H1 : !).s (z) :'.S r,.Our
decision rule is then to reject the set of null hypotheses (13) in favor of
(14) if:
(17)

For dual tests, we proceed similarly, noting that the signs in ( 15) and
(16) are inverted. We thus build a confidence interval t.g(p) - 112,,.(p¡((B)
and reject (15) in favor of (16) if
(18)

1

1
1

to be testedagainstanaltemativehypothesiswhichisanintersectionofalternativehypotheses
H1 : t.'(z) $ Oforall z E (0,z+J.

'

1 '
1,

(14)

There remains to define ¿•(z), Ll'(p),u4.&lt;•&gt; ªºd u4•(p)· Let H be the number
of sample observations ofincomes from a distribution j, yJ, ...,yf. Then,
we have that
(19)

For dual tests, we use a union of mili hypotheses

1

H0

:

t."(p) &lt; Ofor sorne p E (O, 1)

(15)
(20)

to be tested against an intersection of altemative hypotheses
where the empirical distribution function is given by
H1 : t.' (p) ~ Ofor all p E (O,1].

(16)

F;(Y) = ?3(z; O),
1

1 1

Our decision rule will be to reject the union set of null hypotheses in
favor ofthe intersection set of altemative hypotheses only if we can reject
each of the hypotheses in the null set at a 100 · 0 % significance level.
This can be conveniently carried out using a 100 · (1 - 0)% one-sided
confidence interval, a devise we use repeatedly in the empirical Mexican
graphs below. To see how this can be done, denote by ~'As (z) the sample
estimator of As (z) , by As 0 (z) its sample value, and by
ª l•(z} the sampling variance of As (z ). Let((B)be the (1 - 0)-quantile of
the normal distribution. Given that ali of the estimators used in this pa4 See Araar (2006).

(21)

and that
(22)

and
H

fs1= H - 1

¿ !/;'.
h=I

(23)

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/ Has Mexican growth been pro-poor?

Revista Perspeclivas Sociales / Social Perspectives primavera/spring 2007. Vo/.9, Num. I /

Using a first-order approximation, we :find
Í'2(gz; a) - P2(gz; a)

function until percentile are given by:

Í'2(gz; a) - P2(gz; a)

+ gzf'fz(gz;a)

({l,i /J,2-

µ¡ µ¡)

111 -

/J,2 -

(26)

l\(gz;a)- P2(gz;a) = .A(gz;a)-P2 (gz;a)

+

:

o(n- 1/2).

(30)

1
1

where

1

(A

1

:µ

1

).

(32)

Suppose that the two empirical distributions come from independent
samples, namely, the selection of the sampling units was made independently in each sample. We then have
(33)
1.

n - 1 {(I(r/' &lt; Q(p)J-v) Q{p) +,J'I [,j' &lt; Q{p)J-C(p)}
+ o(n-112¡

(36)
(37)
(38)

and

E

(27)
(28)
(29)

({l,i: /J,2) _ (A µ¡)]

ÍJ = (f&gt;i(z;a)- Pi(z;a)) -a(P2 (gz;a-1) - P2 (gz;a))

(35)

C'(p)-C{p) =

Therefore, for a&gt; O, we can express .&amp;•(z) - t.•(z) as

1

+ o(n-I12¡

(25)

where Ff'(gz; a) = O: (gzr1 (P2(gz; a - 1) - P2(gz; a)) &gt; 0 for a &gt; 0 and
Ff'(gz;O) = h(gz) &gt; o (the density at gz) for a= O. Hence, we have:

1

Q(p) _ Q(p) = H -' E (1&amp;1' &lt; Q(p)J -v)
/(Q{p))

(24)

+ o(H- 1/2)

+ a (A(gz;a - 1) - P2(gz; a)) [

29

lf, however, the two samples are dependent because they come, for
instance, from the same panel data, then the variance must be estimated
jointly over the two samples and we then have

(34)

For the dual or percentile approach, :first-order approximations of
the sampling distribution of the quantile estimator and of its cumulative

where I[!I" &lt; Q(p)) is is an indicator function taking the value of 1 if its
argument is true and Ootherwise.
Supposing that the number of primary sampling units increases asymptotically to infinity, we can then estimate the sampling distribution
of the above estimators in t.•(z) and l •(p) taking full account of the survey
design. This is done using the procedure described in Duelos and Araar
(2006), pages 284-287, a procedure which takes into account the sampling weights, the sampling design and the number of statistical units
(individuals) within each of the last sampling units (each household
observation in the sample).

Has tbe Mexican economy been pro-poor?
We apply the above methodology using Mexican data spanning the last
decade and a half. Mexico is a particularly interesting economy over
which to test the pro-poomess of growth. Mexico has indeed undergone
very significant economic changes since 1990. After the 1994-1995
economic crisis, which culminated in an important devaluation of its
currency and was probably the most severe in the country's economic
history, rapid growth in exports (facilitated by NorthAmerican Free Trade
and other trade agreements) as well as macroeconomic and public sector
restructuring led to strong growth. Recent institutional changes have inter
afia encouraged competition and growth in transportation, telecommunications, and power generation and distribution. An important issue is
whether this relatively recent tidal growth has "lifted all boats".
The data used for our application come from the National Income

�30

/ Has Mexican growth been pro-poor?

and Expenditure (ENIGH) Surveys collected in 1992, 1998 and 2004.
These sample data are representative at the national level. Toe objective
of the ENIGH surveys has been to collect information on incomes and
expenditures, goods and services used for self-consumption, and socioeconomic characteristics and labor market activities of all household
members. Toe sampling process was stratified and multi-staged, with
the final sampling units being households and all their members.
As is common in Mexico, we use total income per capita as the

1

measure of living standards for all members of a household. To adjust
for temporal variation in prices, we express incómes in reference to the
2004 consumer price index. To correct for spatial variation in prices, we
assess all incomes in reference to rural prices. This is done by multiplying
urban household incomes by the ratio of the rural to the urban poverty
line. Toe rural poverty line in 2004 is often estimated to be around 550
pesos per month per capita. We use the product of household size and
household sampling weight as an expansion factor to ensure that our
samples are representative of the national distribution of the living standards of individuals. For the estimation of standard errors and thus for
statistical inference, we take into account the stratification and multi-stage
structure ofthe survey designas explained at the end of Section 3.

1
1 '·

'

'

1

.1

I •f 1

1 ,,

We begin our investigation by considering the evolution of the
density ofper capita incomes in Figure 1. Toe distribution of per capita
income has worsened until 1998 since the density curves have shifted to
the left. 1t has however ex.hibited a strong and quick recovery between
1998 and 2004, as shown by the shift of the density curve to the right.
Toe estimates of the Lorenz curves and Gini indices presented in Figure
2 and Table 5, respectively, suggest that inequality has decreased between
1992 and 2004. Figures 3 and 4 and the results ofTable 5 suggest that
absolute poverty, as measured by the headcou.nt and poverty gap indices,
has increased between 1992 and 1998 and decreased between 1998 and
2004.
Formal statistical testing for first-order absolute pro-poomess of
Mexican growth can be done using the information presented in Figures 5 to 1O. Toe top line of Figure 5 shows the sample estimates of

Revista Perspectivos Scciales / Social Perspectives prima,,era/spring 2007. Vc/.9, Num. l /

.ó.1(z) =

?¡9911 (z;o:

= O) - Pum (z;o: = O)

31

(39)

for the difference between 1998 and 1992, whereas the dotted bottom
curve is the lower bound of the one-sided confidence interval,
(40)
Since .!lA{z) - o-¿..&lt;z&gt;((8) &gt; O is verified on Figure 5 for all reasonable
poverty lines, we can infer from our data that growth was absolutely
anti-poor during the period 1992 and 1998. Toe same result obtains from
Figure 6 using differences in quantiles. The sample estimates ofthe difference in quantiles between 1992 and 1998 is shown by the dashed curve,
and the upper bound of a one-sided confidence interval is shown by the
dotted curve. Since we can see on Figure 6 that ~(p) + ªc.•(p)((8) &lt; o
for all percentiles p between O and 0.95, we can again conclude from
our data that growth was absolutely anti-poor during the period 1992
and 1998.
Opposite results are obtained when comparing 1998 to 2004. Judging
from Figures 7 and 8, the change in distribution was first-order absolutely
pro-poor. Toe upper bound of the confidence interval for .!l1(z) is everywhere negative, whatever reasonable poverty line is selected, and the
lower bound of the confidence intervat for .!l1(p) is everywhere positive,
whatever reasonable percentile is selected.
Given the conflicting results reported above, it would seem useful
to check for pro-poomess over the entire period 1992 to 2004. This can
be done using Figures 9 and 10. The distributive change was almost
certainly :first-order absoulutely pro-poor. Toe lower bound of the con:fidence interval for P= (z; a= O)- Pi992 (z; o:= O) is everywhere negative,
again whatever reasonable poverty line is selected, and the lower bound
of the con:fidence interval for the difference in quantiles,Q=(p) - Q1992(p)
is everywhere positive, until at least the O.8 percentile. Thus, the anti-poor
movement of 1992 to 1998 was outdone by the pro-poor movement of
1998 to 2004 so that the entire period of 1992 to 2004 can be inferred to
be overall first-order absolutely pro-poor.
Given the robust results obtained for :first-order pro-poomess, it is not

�32

/ Has Mexican growth been pro-poor?

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Yo/.9, Num. / I

useful to test for second-order pro-poomess since first-order pro-poomess
implies second order pro-poomess. This can be seen by noting that
P; (z; a

= 1) = [ P; (y;a = O)dy.

(41)

If first-order pro-poomess obtains at order 1, then by (41) second-order

pro-poomess also obtains. Toe same relation is obtained by noting from
equations (7), (10) and (12) that the Generalized Lorenz curve condition
is implied by the quantile condition.
Testing for first-order relative pro-poorness can be done using Figures 11 to 20. Figure 11 shows why observing pro-poomess in samples
&lt;loes not mean that we can infer it in populations; to go from sample
pro-poorness to population pro-poomess, we need to apply statistical
inference methods. :ro see this, note that despite the fact that average
income fell by about 30% between 1992 and 1998, the sample estimates of
P¡998(gz;a = O)- Pim(z;a = o) suggest that the distributive movement during that period is first-order relatively pro-poor since that difference
is always negative in the samples observed. But drawing a confidence
interval around the sample estimates make it clear on Figure 11 that the
observed differences Pi998(gz; a = O) - Pim(z; a = O) are not statistically
significant over a wide range ofbottom poverty lines - the upper bounds
of the one-sided confidence intervals extend above the zero line for z up
to around 600 pesos and p up to around 0.28. Hence, with a conventional
level 95% of statistical, the first-order relative pro-poor condition is not
satisfi.ed. An analogous result is obtained on Figure 12 from comparing
growth in quantiles to growth in average income. Again, for a substantial
range of percentiles, the one-sided confi.dence interval overlaps with the
zero line.
1,1

'1
Moving to second-order relative pro-poomess &lt;loes not help, as
shown by Figures 13 and 14. Toe statistical insignifi.cance now extends
overa wider range or z (up to around 900 pesos) and p (up to around
0.4) values. This may seem counter-intuitive at first sight, but it follows
from the fact that statistical uncertainty for first-order comparisons at
the bottom of the distributions builds up at the second-order since second-order conditions are made of cumulatives of first-order statistics (as
discussed above). There is therefore an important lesson to be drawn here.

33

If one were to omit testing for statistical signifi.cance, it might seem that

second-order relative pro-poomess over the 1992-1998 period certainly
cannot be weaker than first-order relative pro-poomess over the same
period. But if one takes into account the effect of sampling variability at
the bottom of the distribution, than the evidence for second-order relative pro-poomess is statistically weaker than that for first-order relative
pro-poomess.
Testing for relative pro-poomess between 1998 and 2004 is more
conclusive, as shown on Figures 15 and 16. The confi.dence interval
around the sample estimates of P2004(gz;a = O)-P1993(z;a = O) on Figure
15 is always below zero for z up to around 1200 pesos (as opposed to
1800 pesos for the sample estimates), which leads us to infer a robust
first-order relative pro-poomess change in that period. A similar result
is obtained on Figure 16 from comparing growth in quantiles to growth
in average income. For a range of percentiles up to about 0.7, the lower
bound of the confidence interval lies above the zero line.
Given the above results, it would seem interesting to test for
second-order relative pro-poomess for the 1998-2004 period. The
results are shown on Figures 17 and 18. We now obtain even stronger (and very strong) evidence of the relative pro-poorness of that
period. The confidence interval is always below zero for differences
P,oo,(gz;a = 1) - P1998(z;a = 1) and above zero for differences C-.(p)/C,-(p) µ,oo,/µu,~- 2004 1998 2004 1998 This is not surprising given that, as discussed above, if first-order pro-poorness is verified statistically at order
1, then we can expect second-order pro-poorness also to be inferred
statistically.
Toe results ofthe tests for relative pro-poorness over the period 1992 to
2004 are even stronger. These are shown on Figures 19 and 20. Toe confidence interval around the sample estimates of P2ro1(gz; a = O)- P,998(z; a =O)
on Figure 19 is always below zero even as we extend z beyond 3000
pesos. Toe same strong evidence is displayed on Figure 16 from the
comparison of growth in quantiles to growth in average income between
1992 and 2004. For a range ofpercentiles up to about 0.9, the lower bound
of the confidence interval is everywhere above the zero line. Hence, the
period 1992-2004 shows a statistically and ethically very robust degree

�34

/ Has Mexican growth been pro-poor?

Revista Perspeclivar Sociales / Social Perspectives primaveralspring 2007. Vol.9, Num. ¡ ¡

Table 1: Descriptive statistics

of relative pro-poorness change in that period.

Stali.stics

1 1992
Sample siz.e (bouseholds) 10530
Gini index
0.622
(0.017)
Average income pet capita: 2115
(142)
[6.52]
1.000
µ.year/ µ.JJm
(0.000)
Headcount index
0.291
(0.014)
Average poverty g¡ip
0.129
(0.()()1))

Conclusion
This paper proposes techniques to check for whether growth has been
pro-poor. It first reviews different definitions of pro-poorness and argues for the use of methods that can generate results that are robust
over classes of pro-poor measures and ranges of poverty lines. It then
makes it empirically feasible to test for pro-poomess of growth. To do
this, it derives the sampling distribution of the various estimators that
are needed to test for absolute and relative pro-poomess. This leads to
the convenient use of confidence intervals around the curves that must
be ranked in order to conclude that a change has been robustly pro-poor
- or anti-poor.
1
1

'1

These statistical techniques are then implemented using Mex.ico's
National Income and Expenditure Surveys collected in 1992, 1998 and
2004 and taking fu1l account of tbe sampling design ofthese surveys. We
find strong evidence that Mex.ican growth has been absolutely anti-poor
between 1992 and 1998, absolutely pro-poor between 1998 and 2004 and
between 1992 and 2004, and relatively pro-poor between 1992 and 2004
and between 1998 and 2004. Toe assessm.ent of the period between 1992
and 1998 is, however, statistically too weak to lead to a robust evaluation of this period, and this is true botb for both first and second-order
assessments of pro-poomess.

Year
1998
10952 20595
0.577 0.524
(0.011) (0.010)
1492
2430
(69)

(87)

(6.83]
0.705
(0.057)
0.354
(0.022)
0.169
(0.015)

(10.88]
1.149
(0.087)
0.106
(0.()()1))
0.036
(0.004)

- ( ...): Standard errors
- [...]: Sam.pling design effect

Figure 1: Density functions

1

- - 1992
1

~

,1 t

l •11

º !o----;eoo"J;:"---::i:::----.----,-------.
1200
1800
2-400
3000 ·
lncome per capita (y)

35

�36

/ Has Mexican growth been pro-poor?

,-

37

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vo/.9, Num. 1 I

Figure 2: Lorenz curves

Figure 4: Average poverty gap curves:P(z; a

= l)for a range of z

45º 1ne
1998

~

'ii

á

al

li
11..
c.'-!

.2

.4

.8

.6

600

Percentiles (p)

,-

1

11!

1800

2400

3000

Poverly line (Z)

Figure 5: 1992 to 1998 is first-order absolutely anti-poor: Pi998(z; a

Figure 3: Poverty headcount curves: P(z; a= O)for a range ofz

' '

1200

1992
2004

=

Pim(z; a = O)

---- ---.....•

íi~

i

'1 1

.ti

11..~

"l

600
o

o

600

1200

1800

Poverty line (z)

2400

3000

1200
1800
Poverty Une

2400

- -- NuHhorizontal line
- - - - - Difference 1
1·•· ········ Lower bound of 95% confidence interv~

3000

O) -

�38

/ Has Mexican growth been pro--poor?

Revista Perspectivas Sociales/ Social Perspectives primaveralspring 2()()7. Vol.9. Num. / /

Figure 6: 1992 to 1998 is first-order absolutely anti-poor: Q1998(p) - Q1992(p)
o---------_-_=.-..-...-..-..-..=...,..,...,-..,-,-...-..-..-..-..-..-..-...-..-..-..-..- - - - - - - - - -

-------- -- ------- .... --

.

39

Figure 8: 1998 to 2004 is first-order absolutely pro-poor: Q2()()4(p) - Q1998(p)

.

··~-

I\

-- -- .... -,,, ~--·..../'\

1
I

......

''

\ _,

g

I
I

\_;

1
1
1
1
1
1
\

í

\

1
1
1
1

~ .10-----.1-9----.38~----.....f j f - -- -•.7-6------,.95

o+-----...-----.------.---------0

Percentile (p)

.19

1---

- - - Null horizontal line
- - - - - Difference
•······ •· •· Upper bound of 95% oonfidence interval

Pi 998(z; a = O)

=

O) -

.J....----~----...------,-----,------,
o
600

1---

1200
1800
Povertyline

3000

2400

NuB horizontal line
- - - - - Difference
-·····•·· ·• Upper bound of 95% confidence interval

.95

1

1

Figure 9: 1992 to 2004 is first-order absolutely pro-poor: P2004 (z; a

=

P¡992(z;a =0)

0-------------------------

1

.76

,fjf

Pen:entlle (p)

Null horizontal fine
- - - - • Difference
· •·•·•· · ·•· Lower bound of 95% oonfldence interval

Figure 7: 1998 to 2004 is first-order absolutely pro-poor: P2004(z; a

"?

.38

~t------.----.----...----2400
---.. o
600
1200
1800
3000

1---

PoYerty line

Nul horizontal line

- - - - • Difference

·· · ···· ·· · · Upper bound of 95% confidence int~

1

O) -

�40

/ Has Mexican growth been pro-poor?

Revista Perspectivas Sociales/Social Perspectives primavera/spring 2()()7. Vo/.9, Num. J /

Figure 10: 1992 to 2004is first-order absolutely pro-poor: Q2004(p) - Q1992(p)

ª
o+-----------------------'-•.'
\:\

41

Figure 12: 1992 to 1998 is not statistically first-order relatively pro-poor:
Q1993(p)/Q1m(p) - µ,1998/ µ1992

O-f&gt;-------+---------------_.;-..
...

.-··
...............
..·•··

...,·
(

..

CII

.19

1--

.38

.57

.76

Percentile (p)

Null horizontal line
- - - - - Difference
··• ........ Lower bound of 95% confidence interval

1

!

.95

1

.02

.2

.38
.56
Pen:entile (p)

.74

.92

, - - Null horizontal line
- - - - • Difference 1
..... ··· ··· Lower bound of 95% confidence interval

Figure 11: 1992 to 1998 is not statistically first-order relatively pro-poor:

P1998(gz; a= O) - Pi992(z;a = O)

Figure 13: 1992 to 1998 is not statistically second-order relatively pro-poor:
Pi998(9z; a= 1) - Pim(z; a= 1)

o ..

-f""'....._,-,----'-:.:,-..-...-. - - - - - - - - - - - - - - .........
·..
''
CII
''
q
·····......,._.................................__ ,_......._
1

o

''

''

''

''

' ',,

-----------------------1200

1800

Poverty line (z)

2400

, - - NuU horizontal fine
- - - - - Difference 1
· ·······.. · Upper bound of 95% confidence interval

3000

8.. ;----..-----..-----,------,,-----,
o
600

1200

1800

2400

Poverty line (z)

, - - Nu8 horizontal line
- - - - - Diffeience 1
·•·•· · ·· ··· Upper bound of 95% confidence interval

3000

�42

/ Has Mexican growth been pro-poor?

Revista Perspectivas Sociales / Sacia/ Perspectives primavera/spring 2007. Vo/.9, Num. I I

Figure 14: 1992 to 1998 is not statistically second-order relatively pro-poor:

C1998(p)/Cum(p) -

Figure 16: 1998 to 2004 is first-order relatively pro-poor: C2004(p)/C1998(p) -

µ1998/µ1992

/.½J:1J4/µ1995

"'

------------- ---- --,

~ .02+----,.2,------.38.-----.•
56----,J-4-----,
.92

1

'1

\
\

...,q

U')-+------,,------.----.------,-----,
1
O

Pen::entile(p)

lfll

1

.38

.57

.76

.95

Percentile {p)
Null horizontal line

- - - - - D'rfference 1

--· --...... Lower bound of 95% conlidence interval

= O) -

Pi998 (z;a=O)

1

.19

¡---

, - - - Null horizontalline
- - - - - Difference 1
······-···· Lower bound of 95% confidence interval

Figure 15: 1998 to 2004 is first-order relatively pro-poor: P2004 (gz; a

43

Figure 17:

1998 to 2004 is strongly second-order relatively pro-poor:

P2004(gz¡a

= 1) - Pi998(z; a= 1)

111

U')
.------.-----.------,,------,
.. +
o - - - - -600
1200
1800
2400
3000
Poverty llne (z)

, - - - Nun horizontal line
- - - - - Difference 1
.......... · Upper bound of 95% confidence interval

1--

NuB horizontal line
- - - - - Difference
... · ...... · Upper bound of 95% conlidence interval

1

�44

/ Has Mexican growth been pro-poor?

Figure 18:

45

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Vo/.9, Num. 1 /

1998 to 2004 is strongly second-order relatively pro-poor:

C.};(X)4(p)/C1~(p) - JJ,,dXJ4jJJ,1m

Figure 20: 1992 to 2004 is first-order relatively pro-poor: C2004(p)/C1992(p) -

JúJJxM/1'1992

(\1

"l

o

+-----..------.-----------,-----,------,

.02

.2

.38

.56

.74

.92

Percentile (p)

--1· · ·· •· · · ·· ·

Null horizontal line
- - - - - Dlfference
Lov,,er bound of 95% confidence interval

1

--1· ·····•····

1200

1800
Poverty line (z)

.38

.56

.74

- - - Null horizontal line
- - - - - Difference 1
1······ · ··· · Lower bound ol 95% confidence interval

= O) -

o~------------------------

600

.2

Percentlle (p)

Figure 19: 1992 to 2004 is first-order relatively pro-poor: P2004 (gz; a
P1992(z;a = O)

o

.02

2400

NuB horizontal line
- - - - - Difference
Upper bound of 95% confidence interval

3000

1

.92

�46

/ Has Mexican growth been pro-poor?

References

Bour Gui Gnon, F. (2003). "The poverty-growth-inequality triangle,"
Tech. rep., Paris, Agence francáise de développement.

Ravallion, M. and S. Chen (2003). "Measuring Pro-poor Growth," Economics Letters, 78, 93- 99.

Bruno, M., M. Ravallion, and L. Squire (1999). "Equity and Growth in
Developing Countries: Old and New Perspectives on the Policy Issues,"
SSRN Working Paper Series 604912.

Ravallion, M. and G. Datt (2002). "Why Has Economic Growth Been
More Pro-poor in Sorne States of India Toan Others?" Joumal ofDevelopment Economics, 68, 381-400.

Dollar , D. and A. Kraay (2002). "Growth Is Good for the Poor," Journal
ofEconomic Growth, 7, 195-225.

Son, H. (2004). "A note on pro-poor growth," Economics Letters, 82,
307- 314.

Duelos , J . Y. and A. Araar (2006). Poverty and Equity Measure-ment,
Policy, and Estimation with DAD, Berlin and Ottawa: Springer
and IDRC.

United-Nations (2000). "A Better World for Ali," Tech. rep., United
Nations, New York.

'

Eastwood, R. and M. Lipton (2001 ). "Pro-poor Growth and Pro-Growth
Poverty Reduction: What do they Mean? What does the Evidence Mean?
What can Policymakers do?" Asian Development Review, 19, 1- 37.

1

Essama-Nssah, B. (2005). "A unified framework for pro-poor growth
analysis," Economics Letters, 89, 216-221.

1
1

Growth?" Discussion Paper #96, lbero-America lnstitute for Economic
Research, Georg-August-Universitiit, Gttingen.
Me Culloch, N. and B. Baulch (1999). "Tracking pro-poor growth," ID21
insights #31, Sussex, Institute of Development Studies.

1

'¡

47

Araar, A. (2006). "Poverty, Inequality and Stochastic Dominance, Theory
and Practice: Illustration with Burkina Faso Surveys," CIRPÉE Working
Paper #0634.

Duelos, J. - Y. and Q. Wodon (2004). "What is "Pro-Poor"?" CIRPÉE
Working Paper #0425.

1
1

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Kakwani, N., S. Khandker, and H. Son (2003). "Poverty Equivalent
Growth Rate: With Applications to Korea and Thailand," Tech. rep.,
Economic Commission for Africa.
Kakwani, N. and E. Pernia (2000). "What is Pro Poor Growth?" Asian
Development Review, 18, 1- 16.
Klasen, S. (2003). "In Search ofthe Holy Grail: How to Achieve Pro-Poor

World-Bank (2000). The Qua/ity of Growth, New York: Oxford University Press.

�Revista Perspectivas Sociales/ Social PerspeclÍlleS primavera/spring 2007. Vo/.9, Man. J I Pág. 49-63

49

Pro-Poor Food Taxation and Subsidy Reforms in Mexico*
Matbieu Audett, Paul Mak:dissi:j:
Abdelkrim Araar§, Jean-Yves Duclos,r

Abstract
This paper uses a methodology developed in Mak:dissi and Richard
(2007) to identify pro-poor tax reforms in Mexico using the ENIGH
2004 data set. This method, which is based on stochastic dominance,
enables us to identify tax reforms that will be deemed as pro-poor by a
wide spectrum of poverty analysts.

Keywords
Stochastic dominance, Pro-poor, Tax reform.

Resumen
1,

Este trabajo utiliza una metodología desarrollada por Makdissi y Richard
(2007) para identificar las reformas impositivas a favor de los pobres
con datos de México utilizando la información de 2004 de la Encuesta
Nacional de Ingresos y Gastos de los Hogares. Esta metodología, basada

11

*We are grate.ful to Dr. Lourdes Treviño and Professor Jorge Va/ero Gilfor their invita/ion to present this paper at the Eight Symposium on "Capital Humano, Crecimiento,
Pobreza: Problemática Mexicana" that took place in Monterrey, Mexico on October 12
and 13, 2006, and to the participants at that conference for valuable comments.
f GRÉDI, Université de Sherbrooke, 2500, boulevard de l'Université, Sherbrooke,
Québec, Canada, JlK 2Rl; Email: mathieuaudetX@hotmail.com
f Département d'économique, CIRPÉE and GRÉDJ, Université de Sherbrooke, 2500,
boulevard de /'Université, Sherbrooke, Québec, Ganada, JJK 2Rl; Email: paul.
makdissi@usherbrooke.ca
§ Département d'économique and ClRPÉE, Pavillon De Séve, Université Lava/. SainteFoy, Québec, Canada, GlK 7P4; Email: aabd@ecn.ulaval.ca
1Département d'économique and CIRPÉE, PavillonDe Séve, UniversitéLava/, SainteFoy, Québec, Canada, GlK 7P4; Emailjyves@ecn.ulaval.ca

1
1

'1
1
1
1
1

,,
1

1

' . ..

ISSN 1405-1133 C 2007 Universidad Autónoma de Nuevo León, Univeisity ofTexas ofAustin,
University ofTexas of Arlington, Uoiversity ofTeooessee,
Universidad Juárez del Estado de Durango, Universidad de Colima

�50

I Pro-Poor FoodTaxalíon and Subsidy Reforms in Mexico

en la dominancia estocástica, nos permite identificar que reformas
impositivas podrían ser consideradas por un gran número de analistas
como favorables a los pobres.

Palabras clave:
Dominancia estocástica, Pro pobres, Reforma impositiva.

Revista Perspectivos Sociales / Social Perspectives primavera/spring 1007. Vol.9, Num.. J /

51

section will present a brief methodological framework devised by
Makdissi and Richard (2007). The third section presents our analysis
of indirect tax reforms for Mexico utilizing the ENIGH 2004 database.
In closing, we present a brief conclusion and possibilities for future
research.

Methodological Framework
Introduction

1

1

According to Santoro (2006), the economic literature has used three
different approaches to analyze the impact of marginal tax reforms.
The :first approach is based on the work of Ahmad and Stem ( 1984) and
uses a specific social welfare function. The second approach identifies
avenues for tax reform based on aversion to inequality and symmetry of
the social welfare function. This approach was pioneered by Yitzhaki and
Thirsk (1990), Yitzhaki and Slemrod (1991) and Myashar and Yitzhaki
(1996). The third approach considers that marginal tax reforms can
also be used as instruments for reducing poverty. It is based inter alia
on the recent papers of Makdissi and Wodon (2002), Liberati (2003)
and Duelos, Makdissi and Wodon (2006). This last approach allows the
identi:fication of tax reforms that will be considered poverty-reducing by
a wide spectrum of poverty measures.

In this article, we check whether sorne indirect tax reforms affecting
the price of food could also be pro poor. By this, i t is meant that not only
must a tax reform lead to a reduction ofpoverty levels, but it must also be
deemed "equitable for the poor", in that its positive impact must accrue
disproportionately more to the poor.
To accomplish this, we adoptan analytical approach proposed by
Makdissi and Richard (2007) . Building on this approach, this article
attempts to identify Mexican food consumption goods which, through
tax reform, sbould be used to favor pro-poor growth. In doing this, we
also follow on the steps of Araar, Duelos, Audet and Makdissi (2007),
which asked whether growth in Mexico between tbe period of 1992 and
2004 was pro poor.
The remainder ofthe article wil1 be divided as follows. Toe following

Let us suppose that the government wishes to put into place a propoor indirect tax reform. Let us consider three possible scenarios the
government can face:
1. the governmentruns a budgetary surplus and wishes to implementa
marginal reduction in the tax (or a marginal increase in the
subsidy) on good i;
2. the government wishes to reduce the budgetary deficit by
implementing a marginal increase in the tax (or a marginal
decrease in the subsidy) on good i;
3. the government wishes to implementarevenue-neutral indirecttaxre
form.
It must therefore finance a marginal tax reduction on good i (or
a marginal increase in its subsidy) with a marginal increase in
the tax (ora marginal decrease in the subsidy) on good j :,=- i.

Poverty Measurement
We consider that poverty can be measured by an additive poverty index.
This class of indices has the following form:

P (z)

= [ p (y,z)dF(y),

(1)

where y is real income, z is the poverty line, F (-) is the cumulative
distribution of income with support over [O, w], and p (y, z ) is a function
that measures the poverty of an individual with an income y usmg a
poverty line z . We suppose that p (y, z ) 2: O and that p (y, z ) = O for all

�52

Revista Perspectivas Sociales / Social Perspeclives primavera/spring 2()()7. Vo/.9, Num. I /

/ Pro-Poor Food Taxation and Subsidy Reforms in Mexico

y &gt; z. Duelos and Makdissi (2004) use the properties of this function to

53

Budget impact

define classes of poverty indices Il5 • These classes are defined by:
p(y,z)EC'(z),
}
n •(z) = P(z) (-l i p(i) (y,z) ~ Ofor i = O, 1, 2, ... ,s, ,
{
p&lt;1) (z,z) = Ofort = O, 1, 2, ... ,s

(2)

where 8• represents the set of continuous functions that are s-times
differentiable on [o, aj.
When s = 1, an increase in the income of any one individual will
weakly reduce the poverty index. This class of indices is thus Paretian.
Toe indices are also symmetrical due to the fact that exchanging incomes
between two individuals does not affect poverty. This type ofindices are
said to satisfy Pen's (1971) principies for comparing distributions.
The poverty indices included in 112 are also convex. This implies
that they respect the Pigou-Dalton principie of transfer, which states that
a transfer from any one individual to a poorer individual should weakly
decrease poverty. In addition obeying the above principles, the poverty
indices belonging to IJ3 must also respect the Kolm principie (1976) of
transfers, which states that a Pigou-Dalton transfer that takes place at
the bottom of the distribution should have a greater impact on poverty
then one tak.ing place higher up in the distribution. Thus, a progressive
transfer occurring within a lower part of the distribution will reduce
poverty even if it is accompanied by a regressive transfer higher up in
the distribution.
Indices of a class IJswith s greater then 3 can be ethically interpreted
by using the generalized transfer principie proposed by Fishburn and
Willig (1984). This principie states that the greater the order s, the greater
is the sensibility of an index to changes occurring in the lower part of
the distribution.
The Foster, Greer and Thorbecke (1984) are a particular example
of additive poverty measures. Other examples of such indices are given
by Watts (1968), Clark, Hemming and Ulph (1981) and Chakravarty
(1983).

In the case of a revenue neutrality requirement, we must analyze the
impact of a tax reform on overall tax revenue. To do this, we suppose
that the economy has K consumption goods. Say that the government
wants to reduce marginally a tax (orto increase marginally a subsidy) on
a good i and fiñance this with a marginal increase in tax (or a marginal
reduction of subsidy) on a goodj . Denote by R the per capita tax revenue
of the indirect tax system:
K

R(q) =

L tkXk(q),

(3)

k~l

where Xk (q) is average consumption of good k, q is a vector of
consumption prices, and tk is the tax imposed on good k (tk &lt; O if k is
subsidized). Toe price to the producer is supposed to be constant and is
fixed as 1 so that q"' the price of good k, equals 1 + t1c Toe impact of the
marginal reform on per capita tax revenue is then:
dR = { [x¡(q) +

t tk a~q)]

[x;(q) + t tkª~!q)] dt;}.

dt¡ +

(4)

Revenue neutrality implies that dR = O. Combined to (4), this leads to:
dt · = X;(q)
h
,
"f ( X -( ) ) w ere 'Y J

q

1

1 " K
~
+ X.W
L...r-1 tk Ot;

l

+ X;(q) L r-1 t i,

i

,:-,.J&lt;

oxk(q).
8t;

(5)

Wildasin (1984) describes "f as the cost effi.ciency ratio of obtaining one
dollar ofpublic funds by taxing good j to subsidize good i. Yitzhaki and
Thirsk (1990) and Yitzhaki and Slemro~ (1991) find that if "f is superior
to one, it is impossible to have a second-order welfare dominant reform
due to the efficiency loss incurred. Makdissi and Wodon (2002) note,
however, that in a poverty analysis perspective, it is possible to have a
reform that is dominant at ali orders of stochastic dominance even when
'Y is greater than one, so long as that part of the burden is supported by
the non poor.
Identífying pro poor reforms
Toe impact of a marginal change dtk to the tax on a good k will impact

�54

/ Pro-Poor Food Taxation and Subsidy Reforms in Mexico

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Vo/.9, Num. / /

55

the poverty level of an individual with income y by
(13)
(6)
Using Roy's identity and setting the vector or reference prices to the
current price vector, the change in real income produced by a marginal
change in the tax on good k is given by (see for instance Besley and
Kanbur 1988)

and that
(14)
By using the results of equation (13) and (14), we obtain
(15)

(7)
and
wherexk (y, q) is the Marshallian demand ofgood k at the vector ofcurrent
prices. If we introduce this result into equation (6), we have
(8)
We do not wish, however, to determine if a tax reform reduces or
increases poverty, but whether it can be considered pro-poor in the sense
ofDuclos and Wodon (2004) and Araar et al. (2007). For relative propoomess, this is accomplished by comparing p ( z) for the second
period top (y, z) for the first period, using a relative "norm" g. For absolute
pro-poomess with an absolute norm of a, we compare p (y - a, z ) with
p (y, z). For the purposes of this paper, we suppose that the relative norm
g is set to growth in average real income, while the absolute norm a
represents the absolute change in average real income. Let:

m,

1
1

y•R = _ Y_
l+g
y•A = y-a

'1

1
'1

,,,,1

op•R(y,z)
&amp;t,.
&amp;¡lA (y,z)

lJtk

=

op(y, z) 0y•R
~&amp;t,.

=

op (y, z) é)y•A
~ot,.·

(16)
To obtain the impact on total poverty, we integrate (15) and (16)
over the entire income distribution. The result is
-

We now wish to determine how y*R and y*A vary with a marginal variation
in t1c Makdissi and Richard (2007) show that

0

&amp;p(J¡, z) [xé(y, q) -yµ
Xk] dF (y),
-¡¡¡¡-

(17)

and
-

8p (y,z) [
)
[ 0 ~ x.(y) -x. dF (y).

(18)

Makdissi and Richard (2007) then define relative (CD *R) and
absolute (CD*A) pro-poor Consumption Dominance curves as follows:

(9)
(10)
(11)

(12)

[

{ ['t-"-¡}f(,)
C[)f"(y) =

J

CI&gt;f" (z)dx

foc, - 1
for s ~ 2,

(19)

o

and

{ ["l\'1-1]¡&lt;,¡ r.u - 1
CD:,, (y) =

f
•

(20)

CDt•(x )dx for s~ 2.

Comparing equation (17) to equation (19), and equation (18) to
equation (20), Makdissi and Richard (2007) show a series of results.
First, a marginal increase in the tax on good i is relatively pro poor for

�56

Revista Perspectivas Sociales/ Social Perspeclives primavera/spring 2007. Vo/.9, Num. J /

/ Pro-Poor Food Taxation and Subsidy Reforms in Mexico

all indices P (z) E n• {z) and for all poverty lines

z E [O, z+j

if
(21)

Second in a revenue-neutral context, a marginal tax reduction for good
i finanded by a marginal increase of the consuroption tax on good/ is
relatively pro poor for all indicess P (z) E n• (z) and for all poverty lines
z E [Oif+l

(22)

Makdissi and Richard (2007) propose similar in the absolute pro-poor
framework. A marginal increase in a tax on good i is absolutely pro-poor
for all indices P (z) en• (z) and for all poverty lines z E [O, z+] if
CDf" (y) :5 O, Vy E (o,z+].

(23)

Again, in a revenue-neutral framework, a marginal tax increase on goo_d
i financed by a marginal decrease of the consuroption tax on good j 1s
absolutely pro poor for all indices P(z) e n•(z) and for all poverty lines
z e [o,z+Jif
(24)
1,

An Illustration Using ENIGH Data
In this section, we apply the above methodology to Mexican data. The
data used for our application is the National Income and Expenditure
(ENIGH) Survey collected in 2004. This survey is representative at
the national level. Toe objective of the ENIGH surveys was to collect
information on incomes and expenditures, goods and services used for
self-consumption, as well as socio-econoroic characteristics and labor
market activities of all household members. The sampling process was
stratified and multi-staged, with the final sampling units being households and all of their members.
As is comroon in South America, we use total income per capita
as the measure of living standards for all members of a household. To
correct for spatial variation in prices, we assess all incomes in reference

57

to rural prices and multiply urban household incomes by the ratio of
rural to urban poverty lines. We use as a guide a 2004 rural poverty line
set to 550 pesos per month per capita. We weight households by the
product ofhousehold size and household sampling weight. To simplify
the interpretation of figures and discussions, we normalize income by
that rural poverty line so that a household with an income equal to one is
at the level of the rural poverty line and a household with an income of
2 has a "real" income equal to twice that line. To simplify the analysis,
we suppose that there is no relative econoroic efficiency advantage of
taxing one good compared to another (thus we have -r= 1).
This study considers tax reforms affecting Mexican food goods. In
2004, all food goods are exempt of value-added taxes (VAT) in Mexico.
A few ofthese goods are also subsidized. Table 1 presents the percentage
of total food expenditure allocated to various food goods. Toe primary
food basket varíes greatly depending on the income quintile. For exarople,
households in the poorest income quintile have a greater share of their
total food spending on cereals (25.88%) and vegetables (17.03%) than
the richest quintile, which spends relatively more on meats (26.23%) and
fruits (6.49%).
Figure 1 presents the C DR,:s curves for different food categories.
The fust conclusion that can be drawn is that a marginal reduction
in taxes on any category of food goods would be pro poor and that
this conclusion is valid for any poverty index which satisfies the Pen
and Pigou-Dalton principies as well as for all poverty lines. Therefore,
any marginal increase in tax on any food good would be considered
relatively anti poor. Analysts propose from time to time imposing VAT
on certain food goods. These recommendations would be relatively anti
poor in the Mexican context. A different issue, however, deals with what
would happen if a marginal increase in a food subsidy were financed by
a marginal increase in the tax on another food good. Figure 1 suggests
that increasing marginally subsidies on sugar, oils, cereals, vegetables
'\nd tubercules and financing this by a marginal increase in the tax
on zoods such as meat, fish, milk and fruits would be relatively pro
poor ívr any poverty index which satisfies the Pen and Pigou-Dalton
principies as well as for all poverty lines. Hence, it is important to consider
the use to which increases in tax revenues are put to know whether a tax

�58

/

Pro-Poor Food Taxation ami Subsidy Reforms in Mexico

1

59

reform is pro poor or not1

References

Figure 2 presents the C [)A:s curves for various categories of food
goods and for s = 2. A marginal reduction in taxes on sugar or oil would
be absolutely pro poor. This conclusion holds for any poverty index
which satisfies the Pen and Pigou-Dalton principles as well as for all
poverty lines. Further, a marginal increase in a tax on eggs would be
absolutely pro poor up to 1.5 times the current official poverty line.
Finally, a marginal increase in consumption taxes on any other category
of food goods would be absolutely pro poor. This conclusion is true
for the above-stated principles and for all poverty lines. With respect
to revenue-neutral reforms, increasing marginally subsidies on sugar,
oils, cereals, vegetables and tubercules and financing this by a marginal
increase in the tax on goods such as meat, fish, milk and fruits would be
absolutely pro poor at the second-order and for all poverty lines. This
last conelusion is identical to the one at the end of the last paragraph
- indeed, with 'Y= 1, a revenue-neutral reform which is absolutely pro
poor must also be relatively pro poor, and conversely.

Ahmad, E. and N.H. Stem (1984). Toe Theory of Reform and Indian
Indirect Taxes, Joumal ofPublic Economics, 25, 259-298.

Conclusion
1

Revista Perspectivos Sociales I Social Perspectives primavera/spring 2()()7. Vo/.9, Num. J /

In this article, we use a methodology proposed by Makdissi and Richard
(2007) to analyze the possible impact of sorne reforms of the indirect
taxation of food goods in Mexico. Results show that a VAT on food goods
would be relatively anti poor. However, if this reform were accompanied
by increases in subsidies of certain categories of food goods, it might be
possible to implement a pro-poor reform both in relative and in absolute
terms.
Future research could evaluate the whole of Mexico's tax system,
both direct and indirect. An analysis of existing tax and transfer programs
could also be made by adapting the methodology proposed in Duelos,
Makdissi and Wodon (2005). It would also be interesting to study
the structure of public utility tariffs using the theoretical framework
developed in Makdissi and Wodon (2007) as well as the framework of
Araar and Duelos (2007) based on "pro-poor growth curves".
Caution should also be exercised when dealing with reforms that suggest increasing
taxes on milk. In Mexico, a share ofspending on milk by the poorest ofthe population
is indeed subsidized through the long running LICONS program.
1

Araar, A., and J.-Y. Duelos (2007). Pro-poor marginal tax reforms
.
'
numeo.
Araar, A.; J.-Y. Duelos, M. Audet and P. Makdissi (2007). Has Mexican
growth been pro-poor?, mimeo.
Besley, T. and R. Kanbur (1988). "Food Subsidies and Poverty
Alleviation", The Economic Joumal, 98, 701-719.
Chakravarty, S.R. (1983). "A New Index of Poverty", Mathematical
Social Sciences, 6, 307-313.
Clark, S.; R. Hemming and D. Ulph (1981). "On Indices for the
Measurement of Poverty", Economic Joumal, 91, 515-526.
Duelos, J.-Y. and P. Makdissi (2004). "Restricted and Unrestricted
Do~ance for Welfare, lnequality and Poverty Orderings", Joumal of
Publlc Economic Theory, 6, 145-164.
Duelos, J.-Y.; P. Makdissi and Q. Wodon (2005). ''Poverty-Dominant
Transfer Programs: Toe Role ofTargeting andAllocation Rules", Journal
ofDevelopment Economics, 77, 53-73.
Duelos, J.-Y.; P. Makdissi and Q. Wodon (2006). Socially-Improving
Tax Reforms, mimeo.
Duelos, J.-Y. and Q. Wodon (2004). What is Pro-Poor? CIRPÉE Working
Paper #0425.
Fishburn, P.C. and R.D. Willig (1984). "Transfer Principies in Income
Redistribution", Joumal ofPublic Economics, 25, 323-328.

�60

I Pro-Poor Food Taxation and Subsidy Rejorms in Mexico

Foster, J.; J. Greer and E. Thorbecke (1984). "A Class ofDecomposable
Poverty Measures", Econometrica, 52, 761-776.
Kolm, S.-C. (1976). "Unequal Inequality: I", Journal of Economic
Theory, 12, 416-442.
Liberati, P. (2003). "Poverty Reducing Reforms and Subgroups
Consumption Dominance Curves", Review oflncome and Wealth, 49,
589-601.
Makdissi, P. and Q. Wodon (2002). "Consumption Dominance Curves:
Testing for the lmpact oflndirect Tax Reforms on Poverty'', Economics
Letters, 75, 227-235.
Makdissi, P. and Q. Wodon (2007). "Poverty-Reducing and WelfareImproving Marginal Public Price and Price Cap Reforrns", forthcoming
in Journal ofPublic Economic Theory.
Makdissi,
mimeo.

:r. et P. Richard (2007). Pro-Poor Indirect Tax Reforms,

Mayshar, J. and S. Yttzhaki (1995). "Dalton Improving Tax Reform",

American Economic Review, 85, 793-807.
Peo, J. ( 1971 ). lncome Distribution: facts, theories, policies, Preaeger,
NewYork.
Santoro, A. (2006). "Marginal commodity tax reforms: a survey",
forthcoming in Journal ofEconomic Surveys.
Watts, H.W. (1968). "An Economic Definition of Poverty", in D.P.
Moynihan (ed.), On Understanding Poverty, Basic Books, New York.
Wildasin, D. (1984). "On Public Good Provision With Distortionary
Taxation", Economic lnquiry, 22, 227-243.
Yitzhaki, S. et J. Slemrod (1991 ). "Welfare Dominance: An Application
to Commodity Taxation",American Economic Review, 81 , 480-496.

Revista Perspectivas Sociales / Social Perspecfives primaveralspring 2007. Vo/.9, Num. / J

61

Yitzhaki, S. and W. Thirsk ( 1990). "Welfare Dominance and the Design
of Excise Taxation in the Cote d ' Ivoire", Joumal of Development
Economics, 33, 1-18.

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Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vol.9. Num. I /

Pro-Poor Food Taxation and Subsidy Reforms in Mexico

Figure 2. Absolute Pro-Poor Consnmption Dominance Curves, :zmi Order.
-

Table 1 Share of total food expenditure by good and
exoenditure auintiles
Expenditure quintiles
4
Richest
3
2
Poorest
Good
15,90
18,95
21 ,20
23,92
25,88
Cereales
16,47
14,88
14,35
12,77
9,21
Leche
26,23
27,79
25,21
22,99
17,37
Carnes
3,74
2,95
2,34
2,08
2,16
Pescado
2,48
3,28
3,84
4,68
5,58
Huevo
1,27
1,76
1,55
2,24
3,08
Aceites
1,29
1,51
1,62
1,78
Tuberculo 1,92
11 ,17
13,30
13,92
15,18
17,03
Verduras
4 ,56
6 ,49
3,71
3,12
2,27
Frutas
1,18
1,03
1,75
1,42
2,91
Azucar
1,11
1,19
0 ,95
1,12
1,47
Café
12,75
9 ,67
8 ,94
8 ,31
11 ,20
Otros ali

-

0,1 - - - - - - - - - - - - - - - - - ~ ~ 0,05

0,4

P8IIC8do
-0, 1

0,2

"

-

0,15
0,1
0,05

o

.....,~:.;;.=...;;.----------------'

~~~~~~~~~@~~~~~~~
&lt;:&gt;- &lt;:), &lt;:), &lt;:&gt;- &lt;:)• " '
"' "' " '
'\,• '\,• '\,• '\,• '\,•

-0,2

Fuas

-0,25

Ama
Café

-0,3

0,25
1,

--Vermm
~

-0,15

Canes
Pescado

0,3

Lecha

-Hieo

r-----------------------... -----Cereates

0,35

-:_-_- Cere
...,_
al_88.. ·

c...

Figure l. Relative Pro-Poor Consumption Dominance Curves, 2® Order.
0,45

63

Tuben)tjo.

-VIIRkns
Fnns
kDlla
CeM

-----------------------1

�Revista Per.rpecttvas Sociales / Social Perspectives primavera/spring 2007. Yol.9, Num. I I Pág. 65-88

65

Gender-bias in Education Opportunities for Population
Aged 12-18 in Mexico: 1992-2004
Ernesto Aguayo, Joana Chapa,
Erick Rangel, Lourdes Treviño,
Jorge Valerot

Abstract
There is considerable evidence that resources are not allocated randomly
within households, and that resources are unequally distributed within
the family in many developing countries. Such an unequal distribution
of goods usually takes the form of a bias against females. For example,
girls lag markedly behind boys in schooling in many developing countries
even though this gender gap has been declining in recent years. Using an
OLS-Robust model anda ML-Random Effects model for the years 1992,
1998 and 2004 of ENIGH, we did not find enough statistical evidence
to support the idea that poor families, nether in rural nor in urban areas,
provide more education to their 12 to 18 years old sons or daughters. In
fact, contrary to the common belief, we found that non-poor families,
invest more in the education of their daughters, especially in the urban
areas. However, this education discrimination against male children
has been decreasing over the years. It is also found that female head
of households are more likely to have children with higher levels of
schooling and that children having both parents at home or having older
brothers or sisters present higher levels of educational attainment.
Keywords
Education, Discrinrination, Poverty, Intra-family allocation, Mex.ico.

f Facuitad de Economía, Universidad Autónoma de Nuevo León, Loma Redonda 1515
Pte., Monterrey, NL, México, 66450'. Corresponding author:jvalero@faeco.uanl.mx
ISSN 1405-1 133 (} 2007 Universidad Autónoma de Nuevo León. University ofTexas of Austin,
University ofTexas ofA.rlingtoo, University ofTennessee,
Univer.;idad Juárez del Estado de Durango, Universidad de Colima.

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/

Gender-bias in Education Opportunitiesfor Population Aged 12-18 in Mexico: 1992-2004

Resumen
Hay considerable evidencia de que los recursos no están asignados
aleatoriamente en los hogares y de que los recursos se distribuyen
desigualmente dentro de la familia en muchos países en desarrollo.
Usualmente esta distribución desigual del ingreso toma la forma de un
sesgo en contra de las mujeres. Por ejemplo, las niñas van retrasadas
respecto a los niños en la escuela en muchos países en desarrollo aunque
este rezago por género ha ido declinando en años recientes. Utilizando
un modelo de Mínimos Cuadrados Ordinarios robustos y un modelo de
Máxima Verosimilitud con efectos aleatorios y con datos de las Encuesta
Nacional de Ingresos y Gastos de los Hogares para los años 1992, 1998
y 2004, no encontramos suficiente evidencia estadística que apoye la
idea de que los hogares pobres, ni en las áreas urbanas ni en las rurales,
provean más educación a sus hijos que a sus hijas. De hecho, contrario
a lo que comúnmente se cree, encontramos que las familias no pobres
invierten más en la educación de sus hijas, especialmente en las áreas
urbanas. Sin embargo, esta discriminación contra los hijos hombres ha
ido decreciendo con los años. También se encuentra que las mujeres que
son jefas de familia tienen mayor probabilidad de tener hijos o hijas con
niveles más altos de escolaridad y que los hijos e hijas que tienen ambos
padres en el hogar o que tienen hermanos o hermanas mayores presentan
más altos grados de educación.
Palabras clave
Educación, Discriminación, Pobreza, Asignación intrafamiliar, México.

..

Introduction
Toe intra-household allocation of resources has become one of the
most important issues in human capital research. There is considerable
evidence that resources are not allocated randomly within households,
1 See, for

instance, Deolalikar (1993) for Indonesia, Parish ami WU/is (1993) for Taiwan, Schultz (1993) on investments in health and education in many groups ofdeveloping countries. Thomas (1990) finds evidence ofnon-random distribution or resources
in Brazi/ian households, and, to a lesser extent, Deaton (1987) and Svedberg (1990)
find gender bias in Africa. Haddad et al. (1994) provide an overview ofthe literature
on within-household resource al/ocation.

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Vo/.9, Num. / /

67

and that resources are unequally distributed within the farnily in many
developing countries. 1 Becker (1965, 1981) conceives the family acting as a single decision maker which regards child education as an
investment decision. Models of intra-household allocation of goods
that follow Becker's approach assume that the allocation is determined
in one of the following three ways: i) parents allocate resources based
on the differential labor market returns to boys and girls (Rosenzweig
and Schultz 1982); ii) parents allocate resources according to their own
utility, which depends on the well-being of their children (Behrman et
al 1982, Behrman 1988); iii) households allocate resources based on the
productivity of individual members (Pitt et al 1990);
However, several authors have pointed out the limitations of those
approaches and proposed alternative collective models for the analysis
of household behavior. Those models assume resources are allocated
according to the relative bargaining power ofthe family members (Manser and Brown 1980, McElroy and Horney 1981, Ulph 1988 and 1990,
Thomas 1990, Haddad and Hoddinott 1991, Chiappori 1992, Lundberg
and Pollak 1993, Wolley 1993, and Echeverria and Merlo 1999).
Such an unequal distribution of goods usually takes the form of a
bias against females. For example, Bardhan (1984), Behrman (1988),
Harriss (1990), Rosenzweig and Schultz (1982), Sen (1984), and Sen and
Sengupta (1983) provide evidence, based on mortality rates and human
capital investments, that gender bias is important in explaining the household expenditures on health, nutrition and education among children. Pitt
and Rosenzweig (1990), Parish and Willis (1993), Quisumbing (1994),
and others have also worked on the effect of gender bias on investments
in childrend' s human capital.
Brinton (1988) developed the concept ofhuman capital system. In
this system, social and economic institutions - such as family, educational
system and work organization- share the responsibilities ofhuman capital
development across the individual' s life cycle. lt is argued that a cross
cultural perspective in gender strati.fication theory helps understand
gender stratifi.cation in countries with different social, economical and
cultural characteristics than American ones. Under this concept, differential parents' investment in sons and daughters is explained by: parents'

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/

Gender-bias in Education Opportunitiesfor Population Aged 12-18 in Mexico: 1992-2004

perception of sex discrimination by employers, parents' control over
resources for investment in children, extent of government support, sex
preference ofparents, female marriage behavior and degree of flexibility
in life cycle timing human capital development decisions. 2
Furthermore, girls lag markedly behind boys in schooling in many
developing countries even though this gender gap has been declining
in recent years (King and Hill 1993; Behrman 1993). Alderman et al
(1996) report that, in 1990, girls tended to receive less schooling than
boys, particularly in rural areas, low-income countries, and in South Asia.
According to the World Bank (2005), in 1990, secondary school enrollment in low-income countries was 26 percent for girls and 42 percent
for boys.3 By 2001, female secondary enrollment had increased to 41
percent as compared to 51 percent for male enrollment.4
Toe existence and sources of gender bias has become highly relevant
for the case of Mexico where the government has been implementing
social programs aimed at the reduction of gender inequality under the
presumption that there is discrimination against girls in education opportunities. Moreover, in 2004, Secretaria de Desarrollo Social (SEDESOL) conducted the Primera Encuesta Nacional sobre Discriminacion
en Mexico (First Nacional Survey on Discrimination in Mexico). It is
reported that 15% of the respondents think they should not invest in their
daughters' education because they will end up getting married.
1,
1
1

'

'1 1
1

111

'

1

Toe aim of this paper is to determine whether there is evidence
for differences by gender in the allocation of household resources. We
will focus on child education, as measured by the number of years of
schooling completed. Using an OLS-Robust model anda ML-Random
Effects model for the years 1992, 1998 and 2004, we did not find enough

1111t¡

2 For instance,

Brinton (1988) found that Japan has a system ofhuman capital development that encourages greater gender stratification (in favor ofmale children) than the
American system.
3 Based on gross enrollment ratio which is the ratio of total enrollment, regardless of
age, to the population of the age group that officially corresponds to the /evel of secondary education.
4 Primary

male.

school enrollment in 2001 was 72 percent for fema/e and 82 percent for

Revista Perspectivas Sociales / Social Perspeclives primavera/spring 2007. Vo/.9, Num. / /

69

statistical evidence to support the idea that poor families, nether in rural
nor in urban areas, provide more education to ·their 12 to 18 years old
sons or daughters. In fact, contrary to the common belief, we found
that non-poor families, invest more in the education of their daughters,
especially in the urban areas. Fortunately, this education discrimination
against male children has been decreasing over the years. It is also found
that female head of households are more likely to have children with
higher levels of schooling and that children having both parents at home
or having older brothers or sisters present higher levels of educational
attainment.
Toe remainder of this paper is organized as follows. Section II provides sorne background on Mexico's educational gender gaps. Section
m describes de data used and section IV specifies the model. Section
V presents the results and section VI concludes the paper .

Educational Gender Gaps in Mexico
lncreasing human capital investments in children is considered to be
among the most effective ways of encouraging growth and ofalleviating
poverty in developing countries. To stimulate such investments, many
governments in Latín America and Asia have initiated programs to provide financia! incentives for families to send their children to school. 5
In 1997, the Mexican government created Programa de Educación,
Salud y Alimentación (PROGRESA), which in 2002 became OPORTIJNIDADES. This program provides focalized aid on education, health
and food with the objective of forming human capital in the poorest
communities and families in Mexico (Parker and Scott 2001 ). Toe aid
for education takes the forro of monetary transfers to fam.ilies that are
contingent upon their children 's regular attendance at school. Toe transfer
amount varíes with the child 's grade leve! and is greatest for children
in secondary school. Toe benefit level is also slightly higher for female
children who are traditionally thought to have lower secondary school
enrollment levels.
5

Such programs exist, for instance, in Bangladesh, Pakistan, Argentina, Chile, Colombia, Brazil, Nicaragua, and Honduras. See Berhman, Segupta and Todd (2001).

�70

/ Gender-bias in Education Opportunitiesfor Populotion Aged 12-18 in Mexico: 1992-2004

Notably remarkable is the fact, however, that, according to the World
Bank (2005), between 1990 and 2001, secondary school enrolhnent in
Mexico has been higher for female than for male. Table 1 shows that,
in 1990, this ratio was 54 percent for girls as compared to 53 percent for
boys. Toe gender gap widened by 2001 when secondary enrolhnent for
female was 78 percent; 5 percentage points above that for male.
Table 1. School Enrolhnent by Country Group and Education Level
Male
Primarv schoo,--1
Lowincome
Lower middle íncome
Middle income
U"=r middle income
Latinamerica &amp; Caribbean
Mexico
Secondarv schoo/ 2
Lowincome
Lower middle income
Middle income
Unner middle income
Latinamerica &amp; Caribbean
Mexico
Ten;ia,v school 2
Lowincome
Lower middle income
Middle income
UDDer middle income
Latinamerica &amp; Caribbean
Mexico

1990
Female

..

..

94
94

90
90
91
86
98

93
87
100

42

58
58
58
..
53

13
7
10
11
16
17

26
49
50
59

..

54

3
9
10
15
13
13

Male
82
..

..

2000
Female

2001

Male

Female

71
..
..
92

82
93
93
92

72
93
92

94

..

..

100

99

100

47

36

51

41

72
73
78
81
72

70
71
81
87
75

..
78
83
73

..
82
89
78

11

7

12

8

..
..

29
20
21

..

..

..

..

36
25
20

31

22
22

Literature on sex discrimination in education access in Mexico is
limited.6 Lopez (2004) used a probit model to analyze determinants
of secondary schooling enrolhnent in Mexico, and, in contrast to the
aforementioned data about education enrolhnent, found that being a
woman reduces the probability to enroll in secondary school, and this
effect is even higher for rural than urban area. A possible explanation
ofthese findings could be that she used data from ENIGH 1984, 1989,
1992 and 1994, thereby reflecting previous information. Parker and
Pederzini (2001) found that although there seems to be no difference in
primary school enrolhnent and overall years of education between male
and female children, a lower proportion of women attend secondary or
tertiary school.

93

92
96
99

..

71

Revista Perspectivar Sociales/ Social Perspectives primavera/spring 2007. Yo/.9, Num. / /

Table 2. School Enrolhnent for Secondary and High School by Sex in
Mexico 1

..

Secondary
Schoo/
Male
Female
HinhSchoo/
Male
Female

..
..

39
26
21

Source: World Development Indicators 2005, the World Bank
1 Net

emollment ratio. The ratio of total enrollment, regardless of age, to the
population of the age group that officially corresponds to the level of education
shown.

2000

2001

2002

2003

2004

61
61

62
63

64
64

65
66

65
67

46
48

48
51

50
53

53
55

53
57

Source: Calculations based on data from Información Estadística. Instituto
Nacional de Geografía, Estadística e Informática, INEGI and Proyecciones de
la Población de México 2000-2050. Consejo Nacional de Población, CONAPO
(2003)
1

Toe ratio of the number of children of official school age ( as defined by the
national education system) who are enrolled in school to the population ofthe
corresponding official school age.

2 Gross enrollment ratio. Toe ratio of the number of children of official school

age (as defined by the national education system) who are enrolled in school to
the population of the corresponding official school age.

Recently, secondary and high school enrollment in Mexico has been
higher for female than for men. Toe gap is particularly higher for high
school than for secondary school. This observed gap has increased between 2001 and 2004 as shown in table 2.

Data
We use data from the Encuesta Nacional de Ingreso y Gasto (ENIGH)
for the waves 1992, 1998 and 2004. The ENIGH is a national income
Th
.
ere IS, on the other hand, plentifal literature on sex discrimination in the labor market in Mexico. See,for instance, Camero (1995), Valdez (1995), MayerandCordourier
(2001), and Sariñana (2002).

6

�72

/ Gender-bias in Education Opportunitiesfor PopulationAged 12-18 in Mexico: 1992-2004

expenditure survey that emerged in 1984. However, it was in 1992 when
the survey started to be conducted on a regularly basis (biennially).
This database is statistically representative for Mexico and contains
detailed information ofhouseholds for severa! measures of income and
expenditure, socio-demographic characteristics of every member in the
household such as age, education level, and characteristics of the job.
The ENIGH also contains information of the physical characteristics
of the dwelling. This national survey uses houses as sample units and
households as units of observation.
Toe purpose to use data for the waves 1992, 1998 and 2004 is to
compare the evolution of observable and unobservable factors that might
generate differences in education opportunities between boys and girls
in three different points in time. We know that the best way to perform
this kind of analysis is to use panel data and follow the same individuals
through the time. However, we do no have this kind of data source for
Mexico.
Toe original data contained 50,862 individuals from 10,530 households for 1992, 48, 11Oindividuals from 10,952 households for 1998 and
91,378 individuals from 22,595 households for 2004. We decided to drop
domestic workers, temporal visitors and heads of households absent. As
a result, the size of the database decreases to 50,378 observations from
10,530 households for 1992, 47,581 observations from 10,952 households
for 1998 and 91,450 observations from 22,595 for 2004. Additionally,
from the sample of individuals we selected only children between 12
and 18 years old in order to avoid possible bias in the selection of the
sample. 7 These restrictions led to a total of 7,623 children in the 1992
ENIGH aged between 12 and 18 with valid responses for all the variables
employed in this research. In 1998, a total 6,871 children met the age
requirements and had valid responses. Finally, in 2004, a total of 11,109
children aged between 12 and 18 and had valid responses.
Before starting the descriptive analysis of the data it is necessary to
1

Women usual/y gel married earlier than men. Therefore, we decided not to include
children older than 18 because we wi/1 end with a smaller number o/ women and men
in the samp/e. Additionally, because o/the samefact we might end with a biased sample
o/more educated women.

Revisto Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vol.9, Num. J /

73

first define the variables used in this research. Table 3 below presents a
complete list of the variables employed in this research and its definitions. Most ofthe definitions are very transparent and do not need further
explanation with the exception of rural and poor. We consider that an
individual lives in a rural area if (s)he lives in a town with a population
smaller than 2,500 habitants. Additionally, a household is classi:fied
as poor if it has a quarterly per capita income lower than $2,170.82
(measured in 2002 pesos) for urban areas. For rural areas, a household
is classi:fied as poor if it has a quarterly per capita income lower than
$1,615.75 (measured in 2002 pesos).8
Table 4 shows the descriptive statistics of the data. Toe second
column presents the mean values for all the individuals in the sample,
the third and fourth column show the mean values for boys and girls
respectively. The last column contains the difference in means between
girls and boys. Toe :figures presented in parentheses represent the standard deviation for each variable and the :figures in the squared brackets
(in the last column) represent the t statistic for the difference in means.
Table 3. Variable Definitions
Variable
Education
head education
Gender
Poor

hours worked
clúldordet
Rural

-¡:;;e
both parents
2ender Xrural
2ender X nnnr
State dummies
8

Delinition
Years of education of clúld
Years of education of the head of the household
Dummv variable ,.,,.,~1 to 1 if tbe child is hov ancl zero otherwise
Dummy variable equal to I if the clúld lives in a poor household and zero
otherwise
We~ hows worked bv tbe child
Equal to the birth order of the child divided by the total number of clúldren
in the familv
Dummy variable equal to 1 if the child lives in a rural area and zero
otherwise
Aoe oí the child
Dummy variable equal to I if the two parents are present in the household
and zero otherwise
F,,,,,.1 to the interaction between e:eoder and rural
~ual to the interaction between 2ender and nonr
We include state dummv variables as controls

This is the definition employed by the Mexican Technical Committee for Measuring
Poverty (Comité Técnico de Medición de la Pobreza (2002)). lt is worth mentioning
that, in order to estímate this fine o/poverty, the Mexican Technical Committee for
Measuring Poverty uses a different definition o/rural area. They considera household
as rural if it is located in a population smaller than 15,000 habitants andfor the construction o/this variable we use the same definition.

�74

'••11

/ Gender-bias in Education Opportunities for Population Aged I 2-/8 in Mexico: I 992-2004

Toe data shows that girls had 0.25 more years of education than boys
in 1992. Additionally, it is possible to observe a statistically significant
difference of 9 hours between the number of hours worked weekly by
boys and girls in that year. It is also identified a slightly higher proportion
(0.03) ofboys in poverty compared to girls. Toe rest of the variables in
the sample of 1992 do not present any statistically significant difference
between the two groups analyzed. On the other hand, in 1998, girls had,
on average, 0.20 years of education more than boys. In addition, the data
for this year shows that, compared to girls, a slightly higher proportion
ofboys lived in households where the head ofthe farnily is a man. Moreover, boys worked on average 1.87 hours per week more than girls. The
rest of the variables for 1998 do not present any statistically significant
difference between boys and girls. For 2004, the data shows that the difference in years of education between girls and boys is equal to 0.15 in
favor of girls. Toe data shows that, on average, boys work 5.72 hours a
week more than girls and that boys are 0.12 years older than girls in the
year 2004. No other statistically significant difference between the two
groups analyzed was found in the 2004 sample.

Table 4. Descriptive Statistics
1992
Variable
Ecilcllli111
head ewcelion
headgoruler

Po11e
lullrswcd:ed
clild order

Model Specification

Age
bmhpareits

1998
Ewcllli111
head ecbcawm
headgondeJ:

hwtswllked
chldorder

The aim of this study is to explain the differences in schooling between
female and male children within a family and, specifically, if there exists gender bias during the allocation process. In order to do this, we
estimate equations of the form

Bays
652

(235)

(231\

Girls
6.TT
&lt;2321

5.01
(3.74)
0.86

4.99
(3.711)
0.87

5.D3
(3.711.)
0.86

(034)

(034)

(035)

0.39
{0.49)
1030
(19.89)
0.56

037
{0.48)
14h6
(22.36)
0.56
m211
0 .45
{0.50)
14.87
(2.03)
0.89
{031)

0 .41
{0.49)
5.59
(15..51)
0.57
(027)
0 .44
{OJIJ)

Rucol
Age
bmhp1mts

0.45
{OJ!I)
14.83
(2.01)
0.89
{031)

14.79

(199)
0.89
(031)

7.D8

6.98

(235)

(2311)

5.43

536

7.18
(232l
552

(433)

(434)

(431)

0.84
(1]36)
0.48
{0.50)
lhl
(10.08)
0.59
{028)
0.41
{0.49)
14BI
(199)
0.87

0.84
ID36l
0.49
2.53

O.!tl
ID3l!l
0.48
{0.51J)
0.66

(12.66)

(6211)

(034)

1
11

Ali
6.64

(021)

Rucol

Pom,

1

75

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vol.9, Num. J /

(tUD)

0.59
t1128'l
0 .42
(.tl .49)
14.82
(199)

0.87
(.tl34)

0.61)
(0211)

0 .41
{0 .49)
14.78
(1 .911\
0.86
l{J3l!l

Diff,rence in Mems
015*
í4J31
Ofil4
[Dhl]
-0.007
[-093]
0.03
[:237]
-9.06·
[-20.70)
0.009
n .451
-O.DI
[-118)
-0.08
[-1.74]
-0.005
[-0.69)
0.20•

[3.55]
0.15
[1.47]
-OD2•
12J01
-0.002
[-0.17]
. ¡ .97•
[-7.81)
0.003
[D.59]
-0.02
[-1.77]
-OD4

í-0.771
-0.005
[-Oñ8)

21114

(1)

Ecilc111i111
head ecbcalion

where Edu¡¡ is the number of years of formal education completed by
child j in family i. X¡ is a vector of variables which are common to all
family members (we include characteristics of the head of family such
as gender and education, as well as family characteristics such as the
presence of both parents in the household, rural or urban location of the
household, the number of children, and whether the family is classified
as poor according to their income). We also include dummy variables to
control for cultural and other (regional) unobserved differences between
the states of residence of the families. Z¡¡ is a vector of variables which
vary across family members (such as gender, age, child birth order, and

head gondeJ:

Pom,
hiairsvllked
chldord,r

Ruc,t
Age
bclhpue,u

7fil

7.56

(233)
6.n

(233)

(4ñl)
OBI
{039)
031
{0.46)
7.84
(17.'ITI
Ofil
(.tl28)
0.29
{0.45)
14.84
(1.99)
0.82
t1138'l

6 .73
(4h15)
OBI
(.tl39)

031
(.tl.46)
10h2
(19.33)
Ofil
(.tl.111.)
019
{0.45)
1490
(2.01)
0.82
(038')

7 .11
(233)
6.n
(4Sl)

0.82
{039)
031
{0.46)
4.90
/14.117'1
0.63
{028'1
029
l{J.45)
14.77
() .97)
0.83
ID38'l

0.15•
[233)
-0.008
[-0.09)
0 .006
[093)

0 .004
[OJO)
-5 .n•
f-18341
.O .0009
f-0.18)
.0D04
[-0.52)
-0.12•
[-3.45)
0.009
fl 351

�76

/

Gender-bias in Education Opportwlities for Population Aged 12-/8 in Mexico: 1992-2004

hours worked, if applicable). Interactions between gender and rural/urban
status and between gender and poverty status are included to investigate
to which extent gender bias is influenced by each of these conditions.
Toe error term is assumed to have two components: one common to ali
children within a family, 8¡, and another which varíes independently
across siblings, uif.
First, following Parish and Willis (1993), the models are estimated
applying heteroskedasticity-robust methods (Eicker 1967, Huber 1967,
and White 1980). That is, we deal with the issue that errors in the equations are not independent because of the common unmeasured family
effect, O¡, by estímating robust standard errors. 9
Unobservable preferences, however, may influence both the family characteristics and the allocation of resources to cbildren. 10 Toe
instrumental variable approach normally used to solve _this problem
is not feasible in this case because all of the exogenous variables are
contained in the model, leaving no instruments available to identify
the family effect. Instead, we could estímate fixed- and random-effect
models that control for the possible correlation between the regressors
and the disturbance.
A limitation of the :fixed-effect model is that we cannot estímate fJ1 ,
the coefficients of the variables common to ali siblings. Additionally, as
Griliches (1979) emphasizes, the within estimators are not necessarily
closer to the "true" estímators because differentiating may exacerbate
the effects ofother potential econometric problems such as measurement
errors in explanatory variables or endogeneity involving the individual
error component.

0n the other band, one can think ofthe unobserved effect to be uncorrelated with all explanatory variables, whether these variables are fixed
9

We do not know whether robust standard errors wi/1 be larger than usual standard
errors ahead oftime. However, as an empirica/ matter, the robust standard errors are
oftenfound to be larger than the usual standard errors (Wooldridge 2003, p. 261).

°

1 For e:xamp/e, high fertility families may choose to invest less in the education of
each child, leading to a negative correlation between di and the number of siblings,
which, in turn, leads to correlations with related variables such as relative birth order.

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vo/.9, Num. J /

77

across a family or not. In this sense, a child 's education is explained by
his own characteristics as well as bis family ' s background, but there is
an unobserved effect that varies randomly within and across families.
Thus, we can include in a child' s education equation a variable such as
head of family 's education even ifit does not change across siblings. But
we are assuming that head of family' s education is uncorrelated with the
unobserved effect, which contains other family and child characteristics
(see Wooldridge 2003, pp. 469-71).
Therefore, we estímate also equation 1 assuming random e:ffects with
the following speci:fication in the error terms
µ.¡i ~ N(O,

a2,.)

o¡~N(O, &lt;ra)

(2)

(3)

E(µu o;)= E((o¡ ok) = O(i ;,k)

(4)

E(µij JJ.;s) = E(µ;i /.4.i) = E(µ;i /.4.s) (i ;,k; j ~)

(5)

Cov (X;, o;) = Cov (Z¡i, o;) = O

(6)

Notice that in the random effect model /31 represents the mean
value of ali the intersections and 8¡ represents the (random) deviation
~om the mean value of the individual intersection. However, 8¡ is not
directly obse~able and for that reason the error wij (equal to µ¡j + 8i) is
heteros~edastik ( cr 2w = cr 2µ +cr 20) and, therefore, is not appropriate to
use Ordinary Least Squares (OLS) to estímate this equation.

Results
Table 5 reports the coefficient estimates and standard errors for the
two models considered (OLS-Robust and ML-Random E:ffects) for the
years 1992, 1998 and 2004. Each year was estímated independently. Toe
OLS-Robust model presents less signi:ficant coefficients than the ML-RE
~odel. However, both models report similar results. As noted, we include
m our regressions children between 12 and 18 years old having at least
one parent at home. In order to investigate whether families discriminate
am?ng the education given to their daughters and sons, depending on
their rural or urban status and their economic (poor or non-poor) condi-

�78

/ Geruler-bias in M=tion Opponunitiesfor Population Aged 12'-18 in Mexico: 1992-2004

tion, we include the.interaction bétween the variables gender and rural
and gender and poor.
With the inclusion ofthese interaction variables, the coefficient ofthe
variable gender inquires only into the existence of gender discrimination
on education within non-poor urban families (i.e. poor=0 and rural=O).
A negative sign indicates that, after controlling by other individual and
family characteristics, non-poor urban boys expect to achieve less years
of schooling than non-poor urban girls.
In our regressions, the coefficient for the variable gender is negative and significant in all cases. In 1992, the OLS-Robustmodel reports
that, within non-poor urban families, boys have in average 0.3564 years
of schooling less than girls. In 1998, this number decreased to 0.3003
years and by 2004, education discrimination against boys within nonpoor urban families decreased to only 0.1654 years. Toe ML-RE model
reports slightly smaller coefficient estimates than the OLS-Robust model.
In 1992, non-poor urban boys had 0.3382 years of schooling less than
non-poor urban girls; in 1998, this number decreased to 0.2646 years;
and, by 2004, this estímate decreased to 0.1458 years.

1
1

Toe sum of the coefficients of the variables gender and the interaction variable gender x rural allow us to inquire whether non-poor rural
families (i.e. poor=0 and rural=1) discriminate among the education
given to their female and male children (the sum of the coefficients and
standard errors are reported in table 6). Toe OLS-Robust model estimates
that, in 1992, non-poor rural boys obtained 0.3847 years of schooling
less than non-poor rural girls. However, in 1998, gender discrimination
on education within non-poor rural families became statistically not
significant. Toe ML-RE model reports very similarresults. In 2004, the
ML-RE model reports, with statistical significance, that non-poor rural
boys get 0.2505 years of schooling less than non-poor rural girls. In
general, we can affirm statistically that non-poor families, especially in
the urban areas, discriminate against their male children on the education provided. Fortunately, such education discrimination against male
children seems to have been decreasing.
Gender discrimination on education within poor families can be

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Vol.9, Num. J /

79

estimated by adding the coefficients of gender and the interaction between poor and gender for the case of urban families and by adding the
coe:fficients of gender, the interaction between poor and gender, and the
interaction between rural and gender for the case of rural families (table
6). It is generally believed that girls within poor families, especially in
the rural areas, are relatively more discriminated against. Por example,
Oportunidades (formerly Progresa), the Mexican government assistance
program, is intended to alleviate discrimination against girls in the poor
families by offering larger monetary transfers to families with girls attending school. However, contrary to our findings for non-poor families,
we did not find enough evidence to claim that poor families, both in
rural and urban areas, discriminate on the education given to their male
or female children in any of the years of the period under study. It is
noteworthy that discrimination against girls is not even evident in 1992,
before Oportunidades was created. Toe lack of evidence supporting
gender bias against female children on education suggests the need for a
review of assistance programs favoring the investment in human capital
for girls and their impact on a possible education gender gap.
Children in the rural areas used to achieve less years of schooling
than children in the urban areas. However, in the 2004 regressions, the
coefficient of the variable rural (for girls) and the sum of the coe:fficients
of the variables rural and gender x rural (for boys) became statistically
equal to zero (except for girls in the random e:ffects regression). In 2004,
rural and urban children get, on average, the same years of schooling
(table 6).
Poor children complete less years of schooling than non-poor child.ren. In both models and in ali years poor girls are about 0.7 years less
educated than the non-poor ones (reading the coe:fficient of the variable
poor). Similarly, poor boys are about 0.45 years less educated than the
non-poor ones (reading the sum ofthe coefficients of the variables poor
and gender x poor) (table 6).
Toe education level and the gender ofthe head of the household are
also related to the education attainment of children. Female and more
educated head ofhouseholds are more likely to have children with higher
levels of schooling. Children having both parents at home or having

�80

/

Gender-bias in Educa/ion Opportunitiesfor Population Aged 12-18 in Mexico: 7992-2004

older brothers or sisters present have also higher levels of schooling.
Parish and Willis (1993) found this last result in their study for Taiwan
and described that family credit constraints, when all children are young,
force the older ones to leave school and help with the family income.
However, we found that, the larger the family size the fewer years of
education a child will have.
Toe coefficients of the variable age can not be interpreted in this
regression but it was introduced to control for the fact that older children
have more years of schooling. The variable hours worked was introduced
to the model to check whether children leave school to work. We found
a negative and significant relation between hours worked and schooling
but the coefficient estímate of the gender variable was only modestly
modified when we introduced hours worked to the model. Finally, we
included 31 state dummies to control for cultural differences among the
regions of the country.

Concluding Remarks
There is considerable evidence that resources are not allocated randomly
within households, and that resources are unequally distributed within
the family in many developing countries. Such an unequal distribution
of goods usually takes the form of a bias against females. For example,
girls lag markedly behind boys in schooling in many developing countries
even though this gender gap has been declining in recent years.
For the case ofMexico, it is generally believed that girls-more specifically poor rural girls- are educationally discriminated within their
families. It is also claimed that 15 of every 100 parents do not invest on
the education of their daughters because they think girls will get married
and, therefore, investing in their education wil1 be a waste of money.
Furthermore, government efforts to abate poverty have been recently
focused on decreasing the "assumed" discrimination against female
children. Toe government assistance program Oportunidades (formerly
Progresa) gives monetary transfers to poor families conditioned on having their children attending school and health clinics. Intended to reduce
such "assumed" discrimination against girls, transfers are larger for girls
than for boys. We did not find enough evidence to support such believes.

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Vo/.9, Nwn. / /

81

Using an OLS-Robust model and a ML-Random Effects model for the
years 1992, 1998 and 2004, we did not find enough statistical evidence
to support the idea that poor families, nether in rural nor in urban areas,
provide more education to their 12 to 18 years old sons or daughters. In
fact, contrary to the general belief, we found that non-poor families, as
established by the Mexican Technical Committee for Measuring Poverty
(2002), invest more in the education oftheir daughters, especially in the
urban areas. Fortunately, these education differences have been decreasing over the years.
We also found that female head of households are more likely to
have children with higher levels of schooling and that children having
both parents at home or having older brothers or sisters present higher
levels of educational attainment.

�,.
J

00

Table 5. OLS Robust and Random Effect Models: 1992, 1998, 2004
1992
1 OLS-Robust
Std. Err.
Coef.
0.0773 ••
-0.3564
gender
0.1252 ..
-0.7123
rural
0,1339
gender x rural
-0.0282
-0.0853
0.1353
head gender
head education•
0.1334
0.01000.0574
0.0319 •
chlld order
0.0250 ..
-0.1223
no. of chlldren
0.1118 ..
poor"
-0.6311
0,1295 •
gender x poor
0.2422
0.1479 •
both parents
0.2729
0.0178 ..
age
0.5861
0.0020 ..
-0.0145
hours worked

educationª

Random Effects
Std. Err.
Coef.
0.0507 ..
-0.3382
0.0742 ••
-0.7190
-0.0752
0.0856
-0.0723
0.1093
0.0068 ..
0.1313
0.0195 ••
0.0487
-0.1180
0.0154 -0.6725
0.0702 0.0803 ..
0.3255
0,1165 ••
0.2383
0.0106 ..
0.5751
0.0011 ••
-0.0121

N

1998
Random Effects
OLS-Robust
Std. Err.
Std, Err.
Coef.
Coef.
0.0613 ..
0.0717 ••
-0.2646
-0.3003
0,0836 ..
0.1146-0.5554
-0.5807
0.0978 •
0.1569
0.1590
0.1709
0. 1067 ..
-0.5509
-0.5141
0.1467 0.0068 ..
0.1483
·0.1502
0.0082 0.0325 ••
0.0235 ..
0.0880
0.0871
0.0278 ••
-0.1045
0.0177
-0.1149
0.0778 ..
0.1042 ..
-0.5389
-0.4907
0.0900 ..
0.1925
0.2007
0.1344
0.1753 ••
0.11550.6566
0.6839
0.0112 ..
0.0157 ..
0.5513
0.5526
0.0026 ..
0.0048 •
-0.0087
-0.0088

2004
Random Effects
OLS-Robust
Coef.
Std. Err.
Coef.
Std. Err.
0.0426 ••
-0.1 458
-0.1654
0.0695 0.1245
0.1294
0.0619 0.1794
-0,1047
0.0719
-0.1137
0.1608
0.0924
-0.1346
0.1396
-0.1262
0.0050 ••
0.0983
0.0997
0.0091 0.0475
0.0146
0.0196
-0.0149
0.0155 ..
-0.1355
-0.1431
0.0402 0.0604 ..
0.1084 ..
-0.6034
-0.6092
0.0691 ..
0.1505 •
0.2109
0.2538
0.0951 ..
0.1430 •
0.3043
0.3196
0.0234 ••
0.0089 ..
0.7166
0.7278
0.0011 ..
0.0029 ..
-0.0189
-0.0219

..__

~
~
";,

o-

~-

¡;·

~

ª-

.;;·

"

f

i

~:

~
...

;t,

~
etate dummies

IS"

1

6·

0.3651 ..

-1.8711

constan!
slgma_u
slgma_e
rho

R•2

..

0.46
79.57
7,623

F or LR-Chl2
observations
rou

-1 .7145
1.0251
1.4019
0.3484

0.2719 ••
0.0261
0.0162
0.0147
4426
7,623
4,119

-1 .1291

0.3144 ..

0.40
72.10
6,871

-

-1.1560
1.0583
1.4965
0.3334

-

0.2971 ..
0.0299
0.0190
0.0161
3420
6,871
4 040

..

-2.7095

0.4575 ••

-2.5970
1.1065
1.3991
0.3848

-

0.43
75.54
11,109

0.2276 ..
0.0210
0.01 42
0.0120

6930
11,109
7,176

..

"

:,..

1....
';-'

o;;

¡;·

~
~-

....
'O
;e
.:..,

a) years of education; b) less than 1,615 pesos of 2002 per capita for rural households and less than 2,170 pesos for urban households

~

~

*") 95% significant; *) 90% significant.
The sarnple includes boys and girls between 12 and 18 years old living with at least one of their parents.
Source: own estimations with data from ENIGH 1992, 1998 and 2004.

~

e;·

s

fr

Table 6. OLS Robust and Random Effect Models: Coefficient Interactions
1992
educatlon•
non-poor urban
famllles

non-poor rural
familias

poor urban
familias
poor rural
familias

1

OLS-Robust
Coef.
Std. Err.

1998
Random Effects
Coef.
Std. Err.

OLS-Robust
Coef.
Std. Err.

2004
Random Effects
Coef.
Std. Err.

OLS-Robust
Coef.
Std. Err.

Random Effects
Coef.
Std. Err.

-0.3564

0.0773 ••

-0.3382

0.0507 ••

-0.3003

0.0717 ••

-0.2646

0.0613 ••

-0.1654

0.0695 ••

-0.1458

0.0426 ••

-0.3847

0.1283 ••

-0.4134

0.0839 ••

-0.1294

0.1669

-0.1056

0.1024

-0.2791

0.1640 •

-0.2505

0.0687 ..

-0.1142

0.1192

-0.0127

0.0726

-0.0995

0.1173

-0.0721

0.0755

0.0883

0.1408

0.0651

0.0633

-0.1424

0.1243

-0.0879

0.0794

0.0713

0.1269

0.0869

0.0798

-0.0254

0.1485

-0.0396

0.0691

-0.7123

0.1252 ••

-0.7190

0.0742 ..

-0.5807

0.1146 ••

-0.5554

0.0836 ••

0.1794

0.1245

0.1294

0.0619 •

-0.4098

0.1227 ..

-0.3964

0.0812 ..

0.0657

0.1506

0.0248

0.0603

rural vs. urban
(glr1s)
rural vs. urban
(boys)
poor vs. non-poor
(glrls)

-0,7405

0.1109 ••

-0.7942

0,0728 ••

-0.6311

0.1118 ..

-0.6725

0.0702 ..

-0.4907

0. 1042 ••

-0.5389

0.0778 ••

-0,6092

0.1084 ..

-0.6034

0.0604 ..

poor vs. non-poor
(boys)

-0.3889

0.1095 ..

-0.3470

0.0700 ••

-0.2900

0.1192 ..

-0.3464

0.0753 ••

-0.3555

0.1303 ••

-0.3925

0.0591 ••

[..__
~
~

li·

l...
~

¡¡.

~

8:-,
~

_e;

-f
..__

a) years of education

**) 95% significant; *) 90% significant.
The sample includes boys and girls betwee n 12 and 18 years old living with at least one of their parents.
Source: own estimations with data from ENIGH 1992, 1998 and 2004.
00
t.,l

�84

/

Gender-bias in Education Opportunities for Population Aged 12-18 in Mexico: 1992-2004

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/

Gender-bias in Education Opportunitiesfor PopulationAged 12-18 in Mexico: 1992-2004

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Revista Perspectivas Sociales/ Social Perspectives primaveralspring 2007. l'o/.9, Num. / / Pág. 89-175

89

Toe Informal Sector in Mex.ico: Characteristics and Dynamics
Eduardo Rodriguez-Oreggia*

World Bank (2005). World Development Indicators.

Abstract
This work analyzes the dynamics ofthe informal labor market in Mexico
using information from the National Survey of Urban Employment
(ENEU) and the urban section of the Quarterly National Employment
Survey (ENET). In the first part, it compares three periods: 1990-199 l,
1995-1996 and 2003-2004 to study the changes in eight of the labor
market categories using transition matrices. The categories include
dependent informal, dependent formal, employer, self-employed, public
sector, not remunerated, unemployed and, inactive. In the second part,
it uses a multinomial logit model with the mentioned categories as the
dependent variable and it finds that age increases the probability of being in the informal sector and that education increases the probability
of being employed in the formal or public sectors. Toe third part uses
quantile regressions to explore the determination of salaries as function
of the labor market categories. It is found that the categories employer
and public sector have the highest returns.

Keywords
Informal sector, Transition matrices, Quantile regressions, Labor
force.

Resumen
Este trabajo analiza la dinámica del sector informal en México utilizando
información de la Encuesta Nacional de Empleo Urbano (ENEU) y la
parte urbana de la Encuesta Nacional de Empleo Trimestral (ENET)
* Instituto de Investigaciones sobre Desa,w l/o Sustentable y Equidad Social, Universidad Iberoamericana, D.F
Pro/. Paseo de la Reforma 880, Lomas de Santa Fe, C.P. 01219 México, D.F
Te/: 59504339 59504000 x7679 Fax: 59504195
Email: eduardo.rodriguez@uia.mx
T'he author wishes to thank financia/ support from the Secretariat ofLabor and Social
Security. through the Labor Research Grants.
ISSN 1405- 1133 C 2007 Universidad Autónoma de Nuevo León, Univemty ofTexas ofAustin,
University ofTexas ofArlington, University ofTennessee,
Universidad Juárez del Estado de Durango, Universidad de Colima

�90

/ The Jnformal Sector in Mexico: Characterislics and Dynamics

comparando primero tres periodos: 1990-1991, 1995-1996 y 2003-2004
para estudiar mediante el uso de matrices de transición los cambios en
ocho categorías del mercado de trabajo: informal dependiente, formal
dependiente, empleador, auto empleado, sector público, sin pago, desempleado e inactivo. En la segunda parte se utiliza el modelo multinomial
logit, usando como variable dependiente las categorías mencionadas de
la fuerza de trabajo, encontrando que la edad incrementa la probabilidad
de estar en el sector informal y que la educación incrementa la probabilidad de estar en el sector formal o en el sector público. En la tercera
parte se utilizan regresiones cuantílicas para estudiar la determinación
de los salarios como función de las categorías en la fuerza de trabajo
encontrándose que las categorías de empleador y sector público tienen
los más altos retornos.

Palabras clave
Sector informal, Matrices de transición, Regresiones cuantílicas, Fuerza
de trabajo.

Revista Perspectiva&lt; Sociales I Social Perspectives primavera/spring 2007. lf&gt;l.9. Num. J I

91

pared to those in the formal sector, and to know the causes that pull or
push workers to enter the informal sector.

It is well known that many individuals move to the informal sector
due to the lack of opportunities in the formal sector. There are structural
reasons to explain the size ofthe sector, mainly associated with the fixed
costs that taxation and excessive regulations represent, and inadequate
and weak links that prevail between the benefits of social security and
the value workers give to those benefits (Garro, Meléndez y RodríguezOreggia, 2005). An important variable highly correlated with informality
is the percentage of working population not covered by mecbanisms that
protect them against risks, i.e. social security. The proportion of formal
to informaljobs experienced a fall since the end ofthe 80's and until the
mid 90's, followed by a slight recovery in the second half ofthe 90's. The
crisis periods of 1994-95 and first halfofthis decade, have increased both
informality and unemployment, as it can be observed in Figure 1.1
Figure 1.1

Introduction

lnformality in Mexico
8

According to data from the Encuesta Nacional de Empleo (National
Employment Survey), in the last few years about 60% ofMexican working population has been working with no social security, considering it
as a proxy for informal labor. This meaos that only about 18 out of 40
million people have social security as a work benefit.

7

1.2

6

5
0.8
4
0.6

3

0.4

2

ECLAC (2005) has estimated that seven out of ten jobs in Latin
America are created in the informal sector, being Mexico a generator
of more informal than formal jobs. Toe rate of job generation occurs
mainly in micro business, the larger employers in the country. On the
other hand, the demographic pressure on the labor market has caused a
higher growth rate on the supply than on the demand side of the labor
market. According to INEGI, about 1Omillion workers are expected to
join the market in the next years, added to the fact tbat nowadays there
are about eight million inactive individuals waiting their turn to join the
market. Hence, the creation of formal jobs becomes a main challenge
for the economy. It is in this context that becomes essential to identify
informal workers, to know their characteristics and disadvantages com-

02

o

~------------------_.,¡o
1987

1990

1993

1--

1996

1999

Unemployment ~Formal /informal ratio

Source: World Bank (2004)

Recently, given no improvements in the labor market in Mexico
(see World Bank report "Doing Business in 2004: Understanding
Regulation"), unemployment increased but salaries &lt;lid not decrease as
ex.pected. This migbt indicate a change in the way the labor market is
working, which could be associated to a drop in inflation, whicb meaos
that the wages reduction mecbanism through price increases is disap-

�92

/

The lnfonnal Sector in Mexico: Choracteristics and Dynamics

pearing. It is possible that macroeconomic shocks could be associated
with unemployment in the long-run, or with an increase in informality.
There are implications of importance for public policies regarding social
protection and the financing of these schemes.
Since this study focuses on the evaluation and examination oftrends
in the informal sector and its comparative dynamics, the estimation of
labor participation in the formal and informal sectors, and the differences in wages and occupations are important to identify groups that are
socially vulnerable. It is helpful to focus public policy mak:ing on those
who have no social security coverage or have a precarious job.
According to INEGI, it has been estimated that by the next decade,
more than ten million people will join the labor force, thus high grow
rates are necessary in the economy, in order to be able to offer them a
job. Moreover, INEGI estimates that about eight million people are currently unemployed and looking to join the labor market any moment. Toe
importance of this study is based on what a hypothetical severe crisis of
job generation could represent, given that the informal sector would be
the most viable option to generate an income. One ofthe main challenges
here is the incorporation of the informal sector to the formal one and for
the generation of more formal employment in a sustained dynamic it is
vital to learn the cbaracteristics and evolution of the informal sector. If
we consider that in the last years the growth rate of informal jobs has
been higber than the one for formal jobs, this perspective should direct
efforts on poverty fighting and employment to consider workers in the
informal sector.
It is known that for sorne people informality represents a convenient

decision, meaning flexibility anda certain status (according to Maloney,
1999), but on tbe other band, informality represents important social
costs. Informality traps workers and companies in low productivity
operations, and it represents several causes that can difficult the implementation of public policies. Toe informal sector represents no security
bene:fits, and most regulations are evaded, such as tax pay. Toen again,
a strict regulation and taxation, in a country with lax enforcement, could
make informality to generate faster.

Revista Perspectivas Sociales / Social Perspecti:ves primaveralspring 2007. Vol 9, Num. J /

93

Tbis study aims to examine and evaluate the trends of the informal
sector, and analyze its characteristics compared to the formal sector.
Probabilities of cbanging labor sector will be measured overa period of
time by the use of transitional matrices between a formal and informal
job. Toe probability of incorporating a new labor sector will be determined, subject to a set of socio-demographic variables, as well as the
previous labor status. Wage incentives to education and job category
according to income leve! of the worker will be calculated. Toe use of a
dynamic view of sector movements will give a broader perspective on
probabilities, progress, and fall backs that have taken place in moving
from one sector to another. Additionally, the wage impact and choice of
sector can obey a high heterogeneity, which will be considered through
a methodology that allows the identi:fication of individuals with similar
characteristics in the income distribution curve.
Toe justification of this study is given by the possible public policíes that can be focused on the reduction of informality. Steps needed
to achieve so require a precise diagnose of those in the informal sector
and the reasons of being there, together with the identification of winners and losers and their tendencies along time. For society as a whole,
the benefits of reducing informality could be more, since not only more
people would have social bene:fits, but they would contribute with their
taxes to the social development of the country, reducing poverty and
increasing economic development. Property rights would increase, allowing reduction ofsorne costs, and access to services and credits would
be granted and would take the advantages of market expansion.

Labor Markets and Informality:
Different Theoretical Versions
The debate on how to classify and analyze the informal sector has included different perspectives. Several definitions have been coined but
'
two have been widely spread: in the seventies, Tokman (1978) generated a Iiterature stream in which the informal sector is measured as a
segment of the urban economy made of small businesses (less than five
employees), and characterized by easy access, simple technology and
a low capital-work ratio. Tbis definition has been extensively used in
studies in Latin America. However, another de:finition has now been

�94

/ The Informal Secwr in Mexico: Characteristics and Dynamics

widely considered since the mid eighties, in which info~ality is classified as those activities which avoid government regulation (De Soto,
1986; Portes and Sassen-Koon, 1987).
International Labor Organization (ILO) has favored the use of
business size to define informality; however, it is conceptually more
appropriate to use the definition based on avoidance of regulations. B!
using the size-of-business definition, the problem raises on the dete~nation of top number to define informality. Typically, five ~mploye~s _is
the limit number, but there is no technical reason to establish that llllllt.
There would not be a reason either to worry about size if the normative perspective shows interest in identifying workers wi~ a job w~ere
regulations are avoided and as a consequence have no social secunty.
'•

.,,

Aditionally, studies on informal workers frequently include self-employed and whereas self-employment is one ofthe main_characteristics in
LatinAm.erica work conditions for self-employed and informal workers
'
.
usually di:ffer, as well as the regulations each one follows, so the ~alys1s
on informality should bear that in mind. It should also be cons1dered
that labor policies focused on a specific group end up a:ffecting the labor
market as a whole.
Generally, there are diverse streams ofthe literature trying to explain
theoretically the existence of the informal sector in the labor market.
Those streams shall be analyzed in the following subsections.

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vol.9, Num. I /

95

phasized that high labor regulations, especially in Latín Am.erica, are an
incentive to create informal jobs. Informality exists because the private
sector has incentives to avoid regulations, due to the lack of appropriate
reinforcement of these.
Toe suggestion of a dualism in the labor market was first established
by Lewis (1954), who proposed a growth model focused on developing
countries. There are two sectors in these economies, a capitalist one,
modero and formal, anda subsistence economy, informal and traditional.
Basically, workers have different wages depending on the sector of the
economy where they work. Here, workers who do not find a job in the
modero or formal sector have to take one in the informal one. However,
when the formal sector expands, there shall be transferences to this sector
from the informal one.
From a Human Capital perspective, (Schultz, 1961; Becker, 1962;
Mincer, 1962), the approach would indicate that in order to have a duality
in the labor market, different salaries between both sectors would have to
exist among workers with similar personality and labor characteristics.
In this case, workers with low salaries, bad job conditions and in the
traditional or informal sector are perceived as low-productive and not
willing to learn the abilities needed in the modero sector ofthe economy,
where wages are relatively higher and better working conditions prevail,
and the chances to enter the sector depend on capabilities (Doeringer y
Piore, 1971).

Classic theory points out that the informal sector is a clear example of
market economy: perfect, but segmented and with no links to the modern sector. Toe modern sector is considered unable to generate enough
employment, so the excluded workers have to find a second best option,
which is the case of the informal sector. The size of the informal sector
therefore refl.ects the extent of the ine:fficiencies of the market and the
reforms that have to be done, such as the increase in flexibility and efficiency in the labor market (World Bank, 1995).

Most literature is based on Harris and Todaro's (1970) model. It
was first used to explain the migration caused when the expected salary
in urban areas evens the marginal return of agricultura! labor, which
is why migration from rural areas to urban areas happens when any of
the following is true: an increase in urban salaries; a reduction in urban
unemployment; a reduction of agricultural productivity. By adjusting the
model to the informal and formal sector, the informality can be seen as
part of the market that is sent outwards, towards what is not covered by
social benefits, since the remunerations are above the point of equilibrium
in the formal sector.

Others, (see Inter-American Development Bank, 2004), have em-

From a competence theory perspective the informal sector is the non-

Labor Segmentation and lnformality

�96

/

The Informal Sector in Mexico: Characteristics ami Dynamics

regulated part ofthe economy, under a frame where similar activities are
also regulated. Toe economic activity moves freely from the formal to the
informal sector, and the form the later one operates mak:es it impossible
to apply legal action and regulation, hence the legal framework explains
the formation of the informal sector. According to Portes, Castells and
Benton ( 1989), companies in the modem sector aim to reduce costs
through avoiding regulations and sub hiring workers not covered by
social benefits.

....

Here, the informal sector is in disadvantage in a dual market. Ozorio,
Alves and Graham (1995) have argued that "workers protected in the
formal sector have higher average wages, vacations, pensions and legal
protection at work. Opposed to those who cannot :find a job in these
companies and have to take their second best alternative in the informal
sector, small companies oras self-employed, getting involved in intense
activities of workforce and no social benefits. Based on this, thé regulatory or union intervention, for instance, pushes the formal salaries above
the Jevel, so the immigrants, the young, the unemployed, "queue" to
get a formal job, so the rest of the waiting time is spent on the informal
sector.

Segmentation by Wage Difference
In the measurement of labor segmentation between formality and informality, comparing salaries has been the key point (Rosenzweig, 1989).
However, there are two disadvantages to this approach (Maloney, 1999):
the are characteristics not observed by the worker that can be correlated
to tbe sector chosen and wages; the value of characteristics not observed
might not be reported.

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Yol.9, Num. / /

97

ences between formal and informal sector are due to the segmentation
of the market. First, within a neoclassic model, it is assumed that all
individuals have the same level ofinformation. Nevertheless, ifwe think
that informal workers have less information, this could be the reason why
lower mini.mal wages are negotiated compared with formal ones.
Secondly, ifwe assume that labor regulations lead to the redistribution of rather higher salaries than lower ones, we are dealing with salary
redistribution from the highest to the lowest salaries. It would be expected
that the less educated workers compete for a formal job, since they benefit
from the redistribution, while the most educated would prefer an informal
job, and so a company that meets regulations would end up choosing
more productive workers among those with less education, not among
those who are more educated. Since there are non-observables that affect
productivity, following this hypothesis there would be a wage premia
to formality among less educated workers, but a salary to informality in
those with more education.
Thirdly, based on the efficiency wage models by Stiglitz (1974),
and Shapiro and Stiglitz (1984), we have that employers are willing to
pay salaries above the optimal market level and so induce workers to
make an higher productivity effort. If we assume that a formal job is
also a strategic way to increase work effort (such as in the number of
working hours), we would expect to find formal workers in companies
that benefit more from lower levels of shirking. Here the difference in
wages between formal and informal workers is given by the difference
between employers in their capacity to monitor, instead of focusing on
intrinsic characteristics of workers.

Segmentation by Mobility between Labor Sectors
0n the other hand, based on Rosen (1986), it was found that in theory
informal wages should be higher than formal wages, in order to make up
for the benefits not received. However, they could also be lower given
the avoidance of tax payment. As for social security, there would be a
compensatory difference to the informal sector for not having the benefits
derived from social security, which are present in the formal sector.
There are other elements that do not mak:e it clear that wage differ-

Maloney (1999) offers an alternative perspective to segmentation based
on the difference between formal and informal wages. He propases an
analysis ofworkers' labor mobility, using panel data through the conditioned probability offinding a worker in a given sector (formal/informal)
at the end of a period t+1 having he started in a different sector in t. He
argues there are reasons to believe that informality is preferred by a segment of workers, because of the characteristics of this sector (flexibility

�98

/ The Informal Sector in Mexico: Characteristics and Dynamics

of hours for instance), to the inference given by labor regulations, and
to the relatively low productivity of the formal sector in underdeveloped
countries.

.,,

Among other :findings, Maloney mentions that many young workers
move to the formal sector after spending sorne years in the informal sector. He also :finds that a significant number ofmiddle aged workers move
from the formal to the informal sector. This evidence is interpreted as
proofthaty;orkers are free to choose the sector they want to work in. For
young workers, Maloney interprets that the informal sector is preferred
over the formal because of the bene:fits and the training, hence they later
on move to a formal job. Once they acquire sufficient experience and
expertise, those workers prefer to leave their formal jobs to set up their
own businesses. However, Maloney groups together in the informal sector
those working in business with less than five employees and those who
are self-employed. Additionally, it is not possible to leam from data if
choosing the sector has been a self-made decision.
Other Considerations

Focusing on the labor market in Mexico, we face a difficulty adjusting
these theories to practice. For instance, Maloney (1999) has found that
labor segmentation is not necessarily true, but a preference for one or
another. Krebs and Maloney (1999) also suggest that maybe workers
move to the informal sector because they are more attracted to it than to
the formal sector, and not necessarily because the informal sector pays
salaries above the market optimal salary and leads to the creation of
informality. Garro, Meléndez and Rodríguez-Oreggia (2005) found that
value ofbene:fits is observed only in large companies. In addition, Rodríguez-Oreggia (2005) found regional differences, since the value ofsocial
security could be higher in areas near the border with the USA .1
Based on Tokman (1978), the high trend of informality in Latin
American countries exists because those countries are new to development and process of industrialization compared to more developed coun1 Jt was Jound that in Brazil segmentation may happen in the lowest income /evels,
while in the highest levels informality is chosen because of convenience (I'annuri-Pianto and Pianto, 2004).

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. Vol.9. Num. J /

99

tries, and besides they are marginal in the global economy. According
to Tokman, this context makes it difficult to generate more jobs, having
a low investment and a large number of immigrants moving from rural
to urban areas, which tends to create more informal jobs. However, this
analysis gives no room to government intervention in public policy making.
From the perspective of globalization, Portes (1994) points out that
it has hada relevant role in the growth of informality, since intemational
competence takes companies to reduce labor costs in order to survive in
the market by the use of outsourcing. Goldberg and Pavnick (2003) find
that at studying the opening oftrade related with informality, institutions
are highly significative, since companies tend to respond to opening by a
reduction of formal jobs when operating in a strict labor environment.
Reinforcing laws can also be an important cause of informality.
Itzigsohn (2000) mentions, when comparing informal sectors in the
Dominican Republic and Costa Rica, that the later one is lower due to
a higher reinforcement of regulations, as a result of an important difference in the setting up and running of institutions. Auerbach, Genoni
and Pagés (2005) consider it difficult to implement mandatory saving
programs such as retirement programs in developing countries that do
not apply enforcement, as it is the case in Latin Arnerica.
Auerbach, Genoni and Pagés (2005) also found that for several Latin
American countries, there are similar pattems of contribution between
employed and self-employed, between individuals and household characteristics, which suggest there are demand factors that explain the decision
on contribution (formality), as well as the fact that sorne workers, such
as those in small companies who eam less than the minimal wage, have
no room in this formal market.

In this paper, the dynamic of informality regarding other labor status
for individuals in Mexico is analyzed. First, probabilities of being in a
sector will be calculated using transition matrices. Toen, the decisions
of joining a given sector will be analyzed depending on a set of sociodemographic factors and previous labor sector. Finally, wage incentives
to education and to labor activity will be measured, depending on the

�]00 /

The Informal Sector ín Mexíco: Characterístícs anti Dynamics

Revista Perspectivas Sociales I Social Penpeclives primaveralspring 2007. Vol.9. Num. 11

income level of the worker.

This section aims to set evidence on the dynamics of switcing from formal
to informal jobs by using Markov transition matrices, which describe a
worker's probability of moving from one job category to another for a
given period.

In Table 3.1 each row describes the probability of being in a given
sector depending on the sector from the previous period. So, the probability of a worker who started in period (t-1) as formal (formal=O) and
at the end ofthe period stays as formal would be q, while tbe probability
of a worker who started the period as formal, but ended up as informal
(informal=!) would be 1-q. It is important to note that the possibilities
are given within each line, so the probabilities should add up along each
line.

Markov Transition Matrices between Labor Sectors

Data

In this section, we shall determine the mobility between sectors, using transition matrices (Markov's), considering the sector where the worker started and ended up at the end offive quarters using data from the National
Urban Employment Survey (known in Spanish as Encuesta Nacional de
Empleo Urbano or ENEU) and the urban part of the National Quarterly
Employment Survey (Encuesta Nacional de Empleo Trimestral, ENET).

In order to analyze the transitional dynamics between sectors, we need
panel data, which will allow us to follow up the same worker in a given
period of time. Through tbe Encuesta Nacional del Empleo Urbano
(ENEU) and the urban part of the Encuesta Nacional de Empleo Trimestral (ENET), it is possible to follow up a twenty percent of workers
along five consecutive quarters. This means we have a rotation panel,
where the fifth of all household selected are substituted each quarter.
While longer time periods are needed in order to know what happens in
a worker's life cycle, it is possible to identify in this period those workers
who move between sectors, as well as their characteristics.

Labor Market Transitional Dynamics

'•

...

Transition matrices can be used in situations where there is a set of
defined status or conditions, and there is a transition from one to another,
and where being in a state depends on the previous one. They also require
information on the previous state or condition. Due to the fact that elements in the matrices represent conditional probabilities, they should be
read as an application of conditional probability to related events.

............. ,

101

These matrices, called Markov, arrange in a matrix of ten the probabilities for a worker who started in a labor sector to be in the same or
another one at the end of the period. Let us state there are only two sectors in the labor market: formal, denoted Oand the informal, named 1.
A degree one Markov's model would specify that the probability for a
worker to be in the current period t in a given sector would depend on
the prevailing state in the previous period, t-1. The stochastic process
describing the dominant sector is defined by two transitive probabilities
calledp and q. Ifwe arrange probabilities between sectors, we have:
Table 3.1
t
Fonnal=O
t-1

Fonnal=O

a

Informal= !

1-o

Informal= !
1-a
p

Three different periods of time are used. First of all, we use from
the third quarter in 1990 to the third quarter in 1991, which represents a
growth and relative bonanza period in the Mexican economy. Secondly,
we use from the third quarter in 1995 to the third quarter in 1996, which
corresponds to a period of crisis in the domestic economy. Finally, we
use from tbe third quarter in 2003 to the third quarter in 2004, a period
of stability in the economy. We tried to use the panel of the first periods
in the survey, but many errors were found when trying to give a sequence
(i.e. in dramatic changes of age, education, gender) so we chose the use
of the period mentioned above in the early nineties.
Categories used derive from the labor market structure itself, which
allows us to follow the Mexican employment survey. Thus, we suggest
the use of the following categories:
Informal Employment: if the worker is in the prívate sector and has

�l 02 /

The Informal Sector in Mexico: Characteristics and Dynamics

no social security in his main job.
Formal Employment: if the worker is in the private sector and has

social security from his mainjob.

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vol.9, Num. J ¡

103

centage of workers who moved to another sector or stayed in the same at
the end of the period under study. The reason this happens is due to the
nature of the employment surveys used, which ask the worker about their
labor conditions on the week previous to the interview, which derives in
information on the initial and final sector.

Public Sector: if the worker has a job in the public sector.

Panel Results 2003-2004
Employer: if the individual states he is an employer.
Self-employed: if worker states he works on his own.

Table 3.2 shows the general transitions between labor categories in the
2003-2004 panel.

Without payment: if the worker states he is working but not receiving

Table 3.2 Transition Matrix 2003-2004. Men and Women

payment.

Informal
Em~~...

.,,

Unemployed: if the individual falls in the definition of open unem-

ployment by INEGI. 2
Inactive: if the individual does not participate in the labor market.

lofcnnal
Einploymeot
Fonoal
Ein ploym eot
Ptablic Scdor
Einploy...
Sclf-anplayed
Wíhoat
paymtnt
Uoemployed
Iaac:tn,·e

Total

Results

S2.96

Formal
Public Employer S.lfWiihoot
Uoemployed
In adive
Em~~... Sector
anel~ed
~mt
14.15
1.52
1.82
11.87
1.57
2.37
13.14

Total
100

9.64

76.IM

1.92

0.95

3.18

0.35

2.39

5.53

100

2.22
8.65
13.8 1
ll.9S

3.16
6.27
4 .01
J.54

87.82
1.73
1.74
1.34

0 .4 7
44.97
5.66
2.32

! MI
31.24
S6.4J
12.32

0.30
2.05
2.61
38.66

0. 84
O. S4
1.0 1
0.73

3.70
4.S4
14.74
29.15

100
100
100
100

2.3.62
6.58
1S. 2S

2 1.67
3.45
19.13

6.22
1.36
11.47

1.24
0.36
3.08

9.24
S.91
13.86

O.Sl
2.34
Z.7S

12.97

24.51
78.35
3Z.S6

100
100
100

1.6.5
1.89

Source: Author's calculations using data ofENET 2003-2004.

The question we want to answer is: Knowing that a worker starts on a
period in a given labor category, what is the probability of changing to a
different category or staying at the current one at the end of the period?
Or, what percentage of workers remained in the same labor category or
moved to a different one?
Using the methodology and data previously presented, the transition
matrices have been calculated using the panels that start in the third quarter and end in the sameoneofthefollowingyears 1990-1991, 1995-1996
and 2003-2004. Matrices are presented in a general way, separated by men
and women, and separated by different age groups in the Appendix.
The results are interpreted technically speaking as probabilities,
however, it can be suggested that each cell in the chart represents a per12 year-old and above individua/s who during the week when the survey was done did
not w ork any hours p er week but were looking for a job or tried to take over an activity
on their own.

2

Toe reading of the data in table 3.2 shows that for this period, a
worker who started as informal employment in the third quarter in 2003
hada 52.96 percentage probability ofremaining in that category. Switching to the right side in the same group, we find that the same worker who
started the period in informal employment hada probability of 14.75
percent of ending up as formal employment; a 1.52 percent probability
of ending up in the public sector; 1.82 percent probability of ending up
as employer; 11.87 as self-employed; 1.57 without payment; 2.37 as
unemployed, and 13.14 as inactive.
Workers who started in formal employment hada probability of76.04
percent of ending up in the same group, followed by a 9.64 probability
of moving to informal employment, or to inactive in a 5.53 percent. Toe
lower probability of movement is 0.95 percentage probability ofmoving
toward employer. Workers in the public sector show a higher probability of staying in the same group at the end ofthe period, with an 87.82

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Revista Perspectivas Sacia/es I Sacia/ Perspeclives primavera/spring 20&lt;J7. fü/.9, Num. JI

/ The Informal Sector in Mexico: Characteristics and Dynamics

percent, whereas probabilities of moving to di:fferent groups are really
low. For example, switching to the inactive group is 3.70 percent.
Those who started as employers have only a probability of 44.97
percent of ending up in the same category, followed by 31.24 percent to
self-employed, 8.65 to informal employment. Self-employed individuals
have a 56.43 percent probability of staying in the same group at the end
ofthe period. Moving to inactive represents 14.74 percent, and informal
employment 13.81 percent. On the other hand, those who started without
payment have a probability of staying in the same group of 38.66, followed by probability of moving to inactive in 29 .15 percent.

......

For individuals who start as unemployed, the probability of ending
up unemployed is 12.97, while the probability of moving to inactive
represents 24 .51 percent, informal employment in 23 .62 percent, formal
employment in 21.67 percent. Individuals who started as inactive have
a 78.35 probability of staying in this group, followed by a probability
of moving to informal employment in 6.58 percent or self-employed in
5.91.Generally speaking, the informal employment group and inactive
seem to be the groups with more frequent movements after staying in
the same category at the end of the period.
By the analysis oftransition matrices by gender, types ofmovements
ofmen and women can be identified in the different groups, as it is shown
in tables 3.3 and 3.4. In table3.3, menshowahigherprobabilityofstaying
in the initial group if they are in the public sector, with lower movements
to other categories. However, for the other groups, being in the informal
employment or self-employed category seem to be in general the prevalent second options after the option of staying in the same group.

~

!nfonnal

Formal

Poblic

Emeloyn,ent
56.76

1:.m2~

... Sector

Emp loyer

S.lf-

Widlout

eme•!!!'.!!!

2:!I!!!eol

Unanp loyed

loadive

16.39

1.76

2.47

13.04

1.40

2.83

5.35

100

10.53

77.84

1.71

1.28

3.86

0.2.5

2.31

2.21

100

2.94
9.77
17.22
23.75

4.25
6.68
5.09
6.25

86.73
L67
1.76
0.83

0.85
46.53
8.24
1.67

2.22
31.75
61.11
15.42

0.20
0.64
1.30
33 .75

0.92
0.51
1.30

1.61

1.90
2.44
3.98
16.67

100
100
100
100

26.39
11.96
21.19

23.46
6.67
27.4 9

6.45
3.07
12.77

1.76
0.84
5.61

12.61
5.60
18 .27

0.88
2.38
1.61

12.90
4.22
2.44

15.54
65.26
10.63

100
100
100

Employment

Public Sed«
Employer
S.lf-anployed

Widlout
payment
Uoemploycd
Inadn-e

Totol

Table 3.4 Transitioo Matrix 2003-2004. Womeo
lnfonnal
Informal

Eme~ent
46.38

Employmeol

Formal
Ernployment
Public Sector
Employer
Self- -loyed
Widlout
pa:ymeol
Uoemployed

lnadive
Total

-

Formal
Public
Eme!!!x!!!ent
11.92
1.10

Employa0.69

S, lf.
Widlout
payment
~12l'.ed
9.86
1.86

Uoemployed

lnadive

Total

1.59

26.60

100

7.89

12.49

2.32

O. J I

1.83

O.SS

2.57

12.04

100

1.46
2.72
8.59
7.07

2.01
4.08
2.34
2.41

88.98
2.04
1.70
1.55

0.07
]6.73
1.70
2.59

0.69
28.57
49.25
11.03

0.4 2
9.52
4.61
40.69

0.76
0.68
0.57
0.34

5.61
15.65
31.23
34.31

100
100
100
100

19.37
5.60
10.18

18.92
2.86
11.97

5.86
1.05
10.37

0.45
0.28
0.92

4.05

0.00
2.34
3.73

13.06
1.19
1.43

38.29

5,96
10.08

80.71

100
100
100

51.32

Source: Author's caJculatioos using data ofENET 2003-2004.

. It seems like in the case ofmen, movement are more often in catc·gones where the worker has no access to social security, while for \\ ,men
changes at the end of the period tend towards inactivity.
Transition matrices based on age group are shown in the appendix.
For those under age, the most frequent movements are towards informal
employment and self-employment. In the group of older workers inactivity is the most frequent group at the end of the period.
'
Panel Results 1995-1996

Total

Employmcnt

Formal

Table 3.4 shows the transitioo matrix for womeo in the 2003-2004 period.
Womeo show a higher probability of staying in the initial group than meo if the
initial group is public sector, without paymeot, unemployed or inactive. Public
sector shows the highest probability of permaneoce, as it happens amoog meo.
However, wheo switching, the first option at the eod of the period is being inactive, followed oot too close by informal employmeot.

Table 3.5 shows the general transitional matrix using the 1995-1996
panel.

Table 3.3 Transition Matrix 2003-2004. Men
Informal

105

Source: Author's calculatioos using data of ENET 2003-2004.

Toe general trend between changes ofcategory is very similar to that
found in panel 2003-2004, being informal employment and inactivity
the ones with the most movements.
. As read in table 3.6, roen show similar trends compared to 2003-2004,
smce the most probable categories to move to are informal employment

�106

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vol.9, Num. / /

/ 11,e Informal Sector in Mexico: Characteristics ami Dynamics

and self-employment.
Table 3.5 Transitioo Matrix 1995-1996. Men and Women
lnfcnnal

Em2~eat

Informal
Jlmployment
Formal
Jlmployment
Public Se&lt;lor
Employer
s.Jf•..,pJoyed
Without

Publi&lt;
Formal
Eme~e111 Sedo!"

Jlmployer

Self.
~l'!!:ed

Withoot
e~mt

Ina&lt;tive

Total

2.98

12.17

100

Unemployed

50.27

16.61

2.34

2.29

11.70

1.65

10.45

75.53

1.99

1.31

3.33

0.43

2.29

4.62

100

3.94
4.21
14.57
29.35

100
100
100
100

25.38
79.48
34.00

100
100
100

2.69
8.51
12.49
11.61

3.13
6.18
4.01
4.27

86. 15
1.88
1.90
1.20

0.79
49.01
7.47
2.41

2.22
26.52
54.96
12.16

0.23
2.24
2.54
37.57

O.SS
1.43
2.05
1.42

Inadive

23.56
6.12

Total

13.96

17.69
3.18
18.38

6.17
1.31
12.04

2.33
0.43
3.77

9.91
5.19
12.66

2.33
2.39
2.84

12.64
1.90
2.34

paymeat

Unemployed

Generally speaking, meo and women show a higher probability of
staying in the public sector, if individuals started in that group at the
beginning of the observation, and the chances of moving to another
category are really low. Women have a higher probability of staying in
the inactive and without payment categories compared to men.

Panel Results 1990-1991
Table 3.8 shows the general traosition matrix using the 1990-1991
panel.
Table 3.8 Transition Matrix 1990-1991. Men and Women

Source: Author's calculations using data ofENEU 1995-1996

37.68

25.66

12.12

63.77

-

Wthout

5.16
8.46
12.85
l.54

payment
Unemployed
bia&lt;tive
Total

19. 18
5.06
11.42

Infonnal

Table 3.6 Transitioo Matrix 1995-1996. Men

....

Formal
Public
Informal
Emeloymmt Jlme~ml s.-

Infonnal
Employment
Formal
Employment
Public:Sect..Employer

Self•employed
Wíthout

payment
Uncmployed
Inadive
Total

Employer

Self•
emel'!!:ed

Without
~ent

Uncmployed

lnadiw

Total

17.80

2.23

3. 11

14.26

1.77

3.03

S.64

100

11.34

76.23

1.95

1.65

4.08

0.53

2.27

1.95

100

2.59
9.09
15.23
26.39

3.84
6.92
5.55
5.90

84.76
1.76
2.00
2.78

1.30
51.03
10.00
3.13

3.35
26.86
59.14
15.28

0.22
0.62
1.50
26.39

1.14
1,55

2.81
2.17
4.14
18.75

100
100
100
100

18.27
6.23
26.38

6.04

3.75
1.36
6.96

12.23
7.26
17.63

2.94
3.83
1.94

15.17
63.42

100
100
100

52.17

28.38
10.57
18.97

2.53
13.85

2.45
1.39
13.21
4.80
3.01

IU6

Source: Author's calcuJations using data ofENEU 1995-1996

For women in table 3. 7 similar trends can be read compared to results
in 2003-2004. Most individuals tend to move to inactivity, followed by
informal employment.
Table 3.7 Transitioo Matrix 1995-1996. Women

.

'

'

Public:
Informal
Fonnal
Eme~mt F.me~mt Sedor

Informal
Employment
Formal
Employmeat
Public: Se&lt;lor
Employer
Self-employed
Wilhout
payment
Uncmploycd
Inadive

Total

2.53

Employer

Self•
emel&lt;!!:ed

Without
~eot

0.87

7.29

1.44

Uncmployed

lnadive

Total

2.89

23.39

100

47.00

14.58

8.54

74.06

2.07

0.57

l.76

0.38

2.32

10.30

100

2.80
4.73
7.74
4.80

2.29
1.35
1.34
3.52

87.79
2.70
1.74
0.48

0.19
35.81
3.08
2.08

0.89
24.32
47.71
10.72

0.25
12.84
4.34
42.72

O.SI
0.68
1.34
1.44

5.28
17.57
32.70
34.24

100
100
100
100

15.69
5.28

16.76
2.61
11.42

6.38
1.08
10.47

0.00
0.26
0.99

6. 12
4.80
8.34

1.33
2.13
3.63

11.70
1.36
1.76

42.02
82.49
53.79

100
100
100

9.61

107

Source: Autbor's calculations using data ofENEU 1995-1996

lmonnal
Employment
Formal
Employm,nt
Pnblic Sed..Jlmployer
Self-anployed

Formal
F.me~ent Em2~"11

Public

Employe,

...

Self•
Witbout
emel&lt;!!:ed
~
11.09
1.62

Unemployed

lnadive

Total

4.47

2.60

1.77

15.11

100

4.73

1.90

6.21

0.71

1.35

9.21

100

13.66
15.36
13.24
l.54

63.43
6. 11
4.62
3.38

1.92
37.30
6.59
1.54

4.50
24.92
43.66
9.85

0.56
1.25
1.63
28.31

0.96
0.47
O.SS
0.92

9.81
6.11
16.l6
44.92

100
100
100
100

26.48
5.85
22.39

7.76
2.98
10.67

1.83
0.59
3.22

10.96
4.43
10.47

1.37
2.44
2.11

731
1.07
1.23

25.11
77.58
38.49

100
100
100

Source: Author's calculations using data of ENEU 1990-1991

From this evidence, the categories to which most individuals move
to at the end of the period are informal employment or inactive. In other
periods studied, it was found that informal employment is a category
with a high tendency to move to, and here formal employment has a great
relevance. This possibly suggests that as from the crisis in the mid nineties, the creatioo of employment has not beeo enough to cover the need
for this type of job, so activities where workers have no social security
have covered this lack of opportunities, generating a differeoce in the
labor dynamics ever since.
We can see in table 3.9 that for meo, the category informal em~loymeot represents the first movement option within a period, while
mdividuals in informal employmeot and self-employment represent a
second place in number of movements. Public sector has more permanence probability, even though in this case it is lower than the previous
periods, after inactivity.

�108

/ The informal Sector in Mexiw: Characteristics ami Dynamics

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vol.9, Num. I /

Table 3.9 Transition Matrix 1990-1991. Men
Public
Infonoal
Formal
Employment Employmeot Sector
27.55

4.96

Employer
3.54

Informal
Employmeot
Formal
Employmeot

39.80
13.41

65.74

4.95

2.55

Public Sector
EmployaSelf-employed
Wilbout
paymeot
Uoemplaycd

7.09
8.41
14.29
16.00

17.06
16.11
16.30
10.00

61.23
6.30
5.28
2.00

3.04
38.70
8.54
1.00

23.08
10.28
16.64

34.62

7.69

13.92

5.25

34.00

13.22

3.08
2.25
6.19

IDadive

Total

Selfempl~ed

represented the one with more movement.
Wilbout

Uoemploycd

Total

lnadivc

~eot

1.84

1.98

6.66

100

0.42

1.52

3.54

100

6.67
0.34
26.09
0.70
48.45
0.93
18.00 29.00

0.84
0.53
1.01
3.00

3.72
3.15
5.20
?l.00

100
100
100
100

16.15
6.53
16.39

6.15
2.89
1.60

8.46
55.14
10.47

100
100
100

13.67
7.85

0.77
3.75
1.48

Toe formal employment category has a higher permanence percentage compared to informal employment, however, informality continues
as the second option after formality for men, whereas inactivity is the
category that takes this place for women. 0n the other hand, an important
percentage of workers move to the informal sector as an altemative to
unem.ployment, for both men and women.

In the case of women, table 3. l Oshows that inactive is the category
with more frequent movement, which is consistent with subsequen~ periods. After this one, formal and informal employment are the opttons
with more movement in the period. Women have a higher probability of
staying in the initial sector than men, when in the public sector, unemployed or inactive.

This is certainly notan alarming indicator of the limited opportunities in the labor market regarding formal jobs. Notwithstanding, this
transition analysis does not answer other relevant questions: what are the
characteristics of workers who remain in the same or move to a different
labor category?, how do these movements take place among education
and age groups?, what aspects of household infl.uence this dynamics?
This is analyzed in the following section, where a multivariable analysis
will be applied to the labor dynamics discussed in this section.

Table 3.10 Transition Matrix 1990-1991. Women

Analysis of Formal vs. Informal Sector Choice

Source: Author's calculatioos using data ofENEU 1990-1991

....

...,

109

Public
Formal
Informal
Employment Employment Sedar
Informal
Employmeot
Formal
Employmeot
Public Sector
Employer
Self-employed
Witbout
paymeol
Uoemployed
Inadive

Total

Employa-

Self!!'.!J!I~

Wilbout
e~eot

Uoemploycd

lnadive

Total

32.91

21.41

3.35

0.48

5.27

1.12

1.28

34.19

100

8.78

58.68

4.14

0.20

1.97

1.48

0.89

23.87

100

2.27
8.96
9.03
0.89

8.58
8.96
5.13
3.56

66.71
4.48
2.87
4.00

0.25
25.37
1.44
1.78

1.26
14.93
31.01
6.22

0.88
5.97
3.49
28.00

1. 13
0.00
0.41
0.00

18.92
31.34
46.61

55.56

100
100
100
100

13.48
4.25
6.79

14.61
4.60
12.09

7.87
2.63
8.42

0.00
0.33
0.59

3.37
4.10
5.23

2.25
2.23
2.68

8.99
0.78
0.89

49.44
81.08
63.31

100
100
100

Source: Autbor's calculations using data ofENEU 1990-1991

The labor dynamics presented in the previous chapter will be analyzed
based on worker characteristics (age, education, gender, marital status),
characteristics within households (head of household, percentage of
member ofhousehold over 65, percentage ofmember ofhousehold under
12, another member of the household has social security at work) and
their labor background (labor category in the last five quarters). With
this data, a multinomial probabilistic model will be used to determine
the effect over choosing among the categories presented in the previous
section.

Results of the Analysis of Transitions
Toe percentage of workers who remained in informal employment after
five quarters has increased as from the early nineties, moving from 32.91
percent (39.80) forwomen(men) at47 (52.17) percentin_the 1995-1996
period, remaining in 46.38 (56.76) in2003-2004. Categone_s wh~r~ most
individuals tend to move are informal employment and macttv1ty for
women and formal employment and/or self-employment/employer for
men. Nevertheless, before the crisis, the formal employment category

Having a dependent variable that changes value according to the
category in the labor market and that can be determined by the probability
of being in the final sector of a period compared to the other sectors, a
Multinominal Logit model shall be used (McFadden, 1974) so that:

p ..
g

=

e x',;/J+/1'
,.y.J

m

iex',P,

�11 O /

The Informal Sector in Mexico: Characteristics and Dynamics

Where Pij is the probability of i to be working in sector j, ~ is the set
of parameters to be estimated and x is the set of matrices of characteristics to be included in the regressions, such as socio-demograpbics of
workers, among others.
Multinominal logit estimators refl.ect labor decisions based on the
utility an individual obtains after making a decision. These decisions are
derived from the hypothesis of maximization ofutility. This unit derived
from a specific category, which depends on certain characteristics.

....

In our case, the dependent variable consists of labor categories used
in the previous sections: informal employment, formal employment,
self-employment, employer, public sector, without payment, unemployed
and inactive. Dependent variables are dummies for: age group [18-25,
26-35, 36-45, 46-55 and 56-65]; schooling [no education, incomplete
elementary, complete elementary, incomplete middle-school, complete
middle-school, incomplete bigh-school, complete high-school, college];
bead of household, married/free union; regions [capital, north, center,
south]; if another member of the household is in the informal sector. Additionally, variables regarding household are included: the proportion of
individuals under 12 years old ofthe total in productive-age in household,
the proportion of individuals 65 years old or more in productive-age
in household. Controls are included for the labor categories where the
individual was at the beginning of the period, i.e. the first period of the
sample.

Data
Data used in this section comes from the micro-data bases ofthe Encuesta
Nacional de Empleo Urbano (ENEU) and Quarterly (ENET), and their
panels, as it was presented in the previous section.
Results
Results 2004
Table 4.1 shows the results for the Multinomial Logitusing 2004 data for
individuals who remained in the panel as from the third quarter in 2003

Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. VoL9, Num. / /

111

and controls were included for their labor category for the previous year.
Toe base category is formal employment, so coefficients are interpreted
as the effect of the variable under study being in a given category compared to the same variable in the formal employment category. Toe table
includes coefficients, standard error in parentheses and the Relative Risk
Ratios, RRR, in brackets. RRR can be read as the times it is probable to
:find a given category in an individual with that characteristic compared
to the base labor category, which is formal employment.
An individual who only di.ffers from reference (Formal Employment)
in gender (man) finds it l. 13 times more probable to be in the informal
employment category. This ratio is higher also in cases where the category
is public sector, self-employed and unemployed. Toe ratio is lower for
men in case of employer, without pay and inactive. Married individuals, ceteris paribus, have a higher probability of being in the informal
employment than in the formal employment, same as public sector or
unemployed. Ratio is higher for employer, self-employed, without pay
and inactive, meaning there is a positive relation.

�-~-f

Table 4.1
Multinominal logit 2003-2004
Public sector

Employer

Self-employed

lY,itb.9\U. pay

Unemployed

Inactive

'~

1235582••·
(.0632848)
[1 131516]

- '.!32514. .
(. 1059136)
[1 131516]

5621431 ·-(. 1429743)
[ 7925387]

-078931'.!
(.0738958)
[1 754428]

-4838133--·
( 123854)
[ 6164283]

0687595
( 1099858)
[1071179]

-1 25793••·
( 0658946)
[ '.!842418]

;¡'%,
~
!l..

- 1788485••·
( 0668017)
[ 83623'.!6]

1559969
( 1083468)
[ 8362326]

4796922•-( 1372577)
[1 168823]

1959639···
(.0750395)
[1 615577]

149328
( 1297121)
[1 161054]

.479972••·
( 13183)
[ 6188007]

2796715·•·
( 0687749)
[1 322695]

Informal employmcnt

MM

N

Marned

"

r
.,

5·

f~Q

Age

~

- 1118694
( 0767866)
[ 894161)

3425026""
( 1358072)
[1408468)

1 09871'.!....
( 1286507)
[3 0003)

6721591 ••·
( 1007733)
[1 958461)

-4116796....
( 1474174)
[ 6625365)

- 2487833"
( 13633)
(.7797489)

- 3596465···
( 0808787)
[ 697923]

!.

1324644
( 0875955)
(1 141638]

6995023···
( 147904'.!)
['.! 012751]

1 634863 ....
( '.!332844)
(5 1J8754)

1 02804"""
( 1088006)
['.! 795581)

.2779048"
( 1572801)
(1 320361]

- 335'.!532•
( 177218)
(.715157]

- 0538705
( 0920139)
[ 9475548]

j

46-55

0231561
( 1051873)
[1 023426]

811314••·
(. 1700751)
['.! 250864]

1 656515""*
(2471382)
[5 '.!41016]

1 27463••·
( 1223251)
[3 577379]

5617314•··
(. 1834461)
[1 753706]

-118619
( 21 13611)
[ 888146'.!]

498897*. .
( 072018)
[1 646904]

56-65

1860573
( 1440111)
[l 204491]

67495'.!3···
( 2324899)
[l 963939]

'.! 247978 ....
(.'.!733977)
[9 46857'.!]

l 747498". .
(. 1535038)
[5 74022]

l 329405•••
(.2324432)
[3 778796]

-1410177
(.3159522)
[ 868474]

1 69721···
( 139493)
[5458699]

-.4366875
(3879232)
[ 6461733)

- 163562
( '.!994869)
[ 8491138)

-4098096""
( 1859243)
[ 6637766)

-.0518675
( 2819455)
[ 9494547)

1176196
( 405738)
[11'.!4816]

-4608826""
( 1823496)
[ 6307267]

26-35

36-45

~-

l
~

¡r

Education
-369732Incomplete Pnmary ( 1772711)
[ 6909195]

"'~-

Table 4.1 {continuation2
Multinominal logit 2003-2004
Inform•l emplc,yment

¡;

Public sector

Employer

Self-employed

~Plf'f

Unemployed

lna.ctive

f

Complete Pnmary

-6790627- •
( 167TT79)
[ 5070921)

-337150
( 3583721)
[ 7138012)

• 3348596
(2873794)
[7154385]

- 6300496•· ·
( 1761844)
[ 5325654]

- 3209738
( 2694943)
[ 7254423]

-4401258
( 3934853)
[ 6439554]

-6818371••·
( 1718098)
[ 5056871]

Incomplete Secondary

· 7517217···
( 200614)
[ 471554)

0200524
( 4340471)
[1 020255]

-646519·
( 3780042)
[ 5238662]

-837'.!321••·
( 2210067)
[ 4329071 ]

• 8521782""
( 3902086)
[ 426485]

· 005438
( 4416985)
[ 9945768]

- 9113593···
( 214427)
[ 4019775]

r'

CQmPl,i;Smrulw!.

1101128•( 1669471)
[ 3324958]

• 18812
( 35030S8)
[ 8285152)

.5779925••
( 2909869)
[ 5610'.?35]

-.9312454•··
( 1764938)
[ 3940626]

-.6616562•·
( 2737207)
[ 515996]

-.4393083
( 383215)
[ 644482]

-1.081792*"*
( 1715066)
[ 3389874]

l¡·

Incompleto Uppcr ~~

-1 29602••·
( 19248'.!4)
[ 2736185]

329277
( 835158)
[1 389963]

-65'.!9882· ·
( 3592899)
[ 5204881]

-1 102891-•
(131306)
[.33191]

- 6478195••
( 2131306)
[ 5231853]

• 178383
( 4089715)
[ 8366'.?2]

.J 036343
( 1973039)
[ 3547495]

Complete Upper Secondary

-1 380219-·
( 172590'.?)
[ 2515235]

5831264
( 3483814)
[1 791631]

- 3988183
( 2983068)
[ 6711126]

-1 160119••·
( 1828231)
[ 313449]

• 699239S••
( 2773919)
[ 4969631]

-4015135
( 3868643)
[ 6693063)[

-1 120307••·
( 1748244)
3261797)

lI

College d,¡ree

-1 439456••·
( 1705893)
[ '.?370567]

1 142926•
( 3432555)
[3 135931]

1926313
( '.!843266)
[J '.!12436]

-1 146978-•
( 1802991)
[ 317595]

-76'.?0834···
( 2781357)
[ 4666931]

1965438
{ 376226'.?)
[1217189)

-1 027446·•·
( 1730049)
[ 3579197]

~
[

!)!

§:

J·
8
:"'

~

,...

!O

1

Labor category previous year

:::::

Informal Employment

3 160829•(.0693153)
(23 59014]

1 562321••·
( 1740637)
[4 769881)

2 385948-•
( 1970453)
[10 86936]

2 882188-·
( 1049738)
[17.85329]

2 902877-•
(279157)
[18 2265]

1 508603-( 1488968)
[4520411)

2 343755••·
( 0916393)
[10.420'.?9]

Pubhc Sector

1771718••·
( 1697315)
[5.880947]

6 705229•··
1503777)
[816 6653]

2 217043• ( 3248958)
[9 18015]

2 289527• ( 2022247)
[9 870272]

2 959607••·
( 4296024)
[19 2904]

'.! 183148-•
(2469714)
[8 874194]

2 687454••·
( 1607584)
[14 69422]

Employe&lt;

24:!03•··
( 18100'.?4)
[11 24924]

2 200259••·
( 3043855)
[9 027355]

5 950851-•
( '.?066178)
[384 0799]

4 610838·•·
( 1680658)
[100 5684)

4 575318-•
( 3670471)
[97 0589]

1 140155 ( 4782778)
[3 127254]

2 532994••·
( 2184972)
[12 59115]

-

...,

�i

i

•

.,,.

Table 4 .1 {continuation2
Multinominal logit 2003-2004
Informal employment

Public sector

Employer

Self-employed

Wtlul.ll1 pay

Unemployed

Inactive

Self-F.mployed

3 168421-·
( 1082537)
[23 76993]

2 835144ººº
( 1869111)
[17 03285]

45192!7···
( l86ll79)
[91 76461]

5 546004-( 1202551)
[256 2116]

4.774825·( 2805938)
[l 18 4896]

2 183407-•
(2116457)
[8 876495]

3 690996·· ·
( 1186653)
[40 08473]

Witbout payment

3 176886°0 *
( 2197094)
[23 97198]

2 610251 •••
( 3735604)
[13 60247]

4352711 •••
(3405058)
[77 68882]

4 490301-•
( 2308433)
[89 14828]

6 979993 - ·
( 3141721)
[1074 911]

1 530828···
( 4617627)
[4 622003]

4 105723º*"
( 2113926)
[60 68661]

Unemployed

2 174583º*"
(.1378685)
[8 798518]

2 389586 •••
( 2234844)
[10 90898]

1 83264:! ....
(4208708)
[6 250381]

2 603837-·
( 1893378)
[13 5155]

517511••
(35057)
[4.560857]

2 574778- ·
( 1801676)
[13.1284]

2756072• ( 1459951)
[15 73791]

Inaetivc

2 653449(.0919166)
[14 20294]

2 680063°* 0
( 1587108)
[14 58601]

2 s21ss•••
( 2500473)
[12 44788]

3 674983...
( 1164468)
[39 44798]

4241957. . .
( 2006571)
[69 5438]

2 423985···
( 1463325)
[11 29077]

4 990086•( 0896634)
[146 949)

• 0929447
( 1476269)
[.9112438)

-166108( 0823218)
[.8469548]

-2 228866• ( 1885292)
[ 1076S04]

- 3938235···
( 1492315)
[ 6744731]

-1 045635°0 *
( 0803677)
[ 3S14684)
- 2210S11
( 325352)
[ 8016757)

• 2107779**"
( 0736071)
[ 8099539]

Head

Yo iru:uu,,~ over 65

Yo 11Wllllm. under 12

Another household m embcr
seeunty

Constont

• 2495684""
( 1202173)
[ 779137)

-0135706
( 3224408)
[ 9865211)

2107735
( 4914487)
[1 234633)

-1 143406
(7885924)
[ 3187314]

3368437
( 3589111)
[1.40052]

-4905436
( 5334553)
[.6122935)

4808828
( 5152431)
[1 617S02)

4947565°••
(1251027)
[1 640099]

0292068
(2051505)
(1 029638]

0069353
( 2146133)
[1 006959)

3008946( 1383974)
[l.351067]

1378865
( 2392527)
[1 147845]

1637335
( 265096)
[1 1779]

2765628( 1330035)
(1 31859]

• 2489609•··
( 0694183)
[ 7796104]

-0824195
( 1149966)
[ 9208856]

- 6236342. . .
( 1596813)
[ 535993)

-.3S50128°••
( 08292)
[ 7011645]

-6621545•··
( 143132)
[ 515739)

- 0767638
( 1184458)
[ 9261086)

-0766255
( 0694773)
[ 9262367)

• 6581702*. .
(:!00651\)

-4 502194••·
( 4067386)

-6 159899•··
( 4246546)

-2.993007- ·
(:!325962)

4 058183••·
d4 l47722)

-2,258856···
( 4231077)

• 8332486·( 2086273)

Table 4.1 ( continuation}
Multinominal logit 2003-2004
Informal employment Public sector

Employer

Sclf•employcd

~ pay

Uncmploycd

Inactivc

-.5013145- •
(.0978262)
[ 6057339)

.0653421
( 1661823)
[1 067524]

-0909832
( 1934615)
[ 913033)

-.2445535( 112079)
[ 7830541)

.1520279
( 1963018)
[1 164193)

• 56058••·
( 1624596)
[ 5708779)

• 1196453
( 1026503)
[ 88723511

Center

• 1364405
( 0976821)
[ 8724582)

1370532
1678939)
[1 146889]

. 3636801( 1922111)
[1 438614)

-.0122647
( 1123815)
[ 9878102)

1895284
( 1960359)
[1 208679)

-.4672034 •••
( 1643211)
[ 6267526)

-.025535
( 1033873)
[ 9747882)

South

0193145
( 1108338)
[1 019S02]

5210719· · ·
( 183623)
[1 683832]

411917••
( 2122752)
[1 509709)

2739427••
( 1255882)
[1 315139]

7062672· · ·
( 2096087)
[2 026413]

-5005121••
( 1980618)
[ 6062202)

197131*
( 1166717)
[1 217904)

N
Log likelihood

Pseudo R2

i

R'¡¡

.,
s·

f~-

?R
a.

~·

t.

f.s

Reeion
Norlh

~

t

Household

w.llh, 1ocial

'

ir;;-

26407
-26291.748

0.4377

Note: Standard errors in parentheses, RRR in brackets. ***, ** and * denote significance at 1, 5 and 10%
respectively. Base total category is formal employment. base categories: women, 18-25 years old, no education, capital.

i¡·

¡r
[
!l

il
i

1

~-

lf
j·

8:--&gt;
~
,-..

-'º

i

._

'

...

UI

�116

/ The Informal Sector in Mexico: Characteristics anti Dynamics

Por age groups, it can be observed that there is a general trend to
increase probabilities as the worker gets older, with important variations
though. Age g:roups are not significant in the informal employment category. Within public sector, the [RRR] ratio increase with age groups,
but tend to decrease in the older group. Por employer and self-employed
categories, the ratio of age groups increases faster than other categories.
In the category without payment, younger groups have a lower probability
ofbeing in that sector than informal employment, but this increases with
age. Por unemployed, the ratios are lower than one, which means there
is a negative relation, additional to the fact that they are only significant
to younger groups. Por the inactive group, the ratio is higher than one
in older groups, so it is probable to fall in this group as the person ages,
rather than being in the formal employment, which is the case for younger
workers.
Regarding education groups, we find important variations in categories and levels. Por instance, an individual in informal employment has
less probabilities of being in this section having more education than in
the formal employment category. Por public sector, the education levels
are not significant. For tbe employer category, education is only significative in mid levels, while in the case of self-employed it is lower than
one and decreasing. Por those in without payment, the lowest education
levels are not significant and all of them are below one. Por the unemployed education is not significant, and for the inactive it is decreasing
and lower than one.
Also in table 4.1, we present the results for the category in which
the individual was in the previous year. In ali cases, being in the same
category the year before gives a higher probability of being in the given
category. Toe second category with more probability after the one under
study is usually self-employment. This indicates this category has a higher
dynamism and it is easier to move to any other category from there.
Within variables that correspond to households, head ofhousehold
has a negative relation in ali cases, which indicates that being head of the
household represents less probabilities ofbeing in any other category different from formal employment. Toe proportion of over 65 compared to
those in productive age within the household is not significant in any case.

RevistaPerspectivas Sociales I Social Perspectives primuvera/spring 2007. Vo/.9, Num. I /

117

For the variable that considers under 12s in the proportion ofproductive
age in the household, it is significant and positive only in the cases of
informal employment, self-employment and inactive, so there are more
probabilities of being in those categories than in formal employment if
there is a higher proportion of individuals under 12 in the household.
The variable that considers if another member of the household has
social security derived from work is always negative, although it is not
significant in the public sector, unemployed and inactive categories. This
is, an individual has less probabilities of being in the informal employment, employer, self-employment or without pay categories than as in
formal employment if someone else in the household has social security
at work.
Regarding controls per region, the central region is only significant in
increasing probabilities ofbeing employer and reduce being unemployed,
while in the north it is significant in reducing the probabilities of being in
informal employment, self-employed or unemployed. Toe south region
has a significant influence in increasing the probabilities of working in
the public sector, being employer, self-employed, without payment or
inactive, while it reduces the probability ofbeing unemployed.

Results 1996
Table 4.2 shows the results for the third quarter 1996, using only individuals observed in the five previous quarters.
Results are very similar in trends to those obtained for the 20032004 period. The only age group that shows positive significance in all
categories is the one for 56 to 65 years old, which meaos the older group
has more probabilities than the younger workers of being in any category
before formal employment. This trend occurs in an increasing way as ,
moving along age groups, except for the unemployed group, where only
the oldest group is significant.
Trends in the effects of education level are similar to those in 20032004. While ali education groups are significan.t and negative for the informal employment category, which meaos the more education the lower
is the probability of being in the informal employment group instead of

�j
_;_,_.I

~

s· &gt;

~

e-

(1)

~-

..... "' -'i'"&gt; ..,
º

t:r' '="&gt;
(1)

Q

::t.

e-

º º'="&gt;
=
S' o

oc::B"''"'B
~ = "2.. ll) ..... ll)

00

'

~

ºººc::g".., 8 '&lt;
o

:j'
~

"'Ij

~

f"2...P.g-i
~
~ - · -o
(1)

(1)
::-. (1) &lt;¡:¡ o
oc.. "' '"'º'"'

¡¡;

....,ll)~g_..§e(l)P...,.ll)cn(l)

o.
e o.

t:r' ::t.

,e

-

:'-'
(") s· 0
.., 0p &lt;-·
e=
ll) ¡:.¡ o. u
e¡t.o-

g

::t. (")
o ::t. .., O"'
e=
t:,&lt;(1)

t:!" t::".
¡:;. . (")

..... (JQCI&gt;

·uo~Ot:r'g

..... s· '&lt;e.~
¡:l"
0

(JQ

u

(1)

,. ,.
Q

cnQ..u

"'"" r::r - · e:
º c= \ . a(") t:r'
!Si.....
~
::t. o
... . (1)
ol:S :::1
(") o
-·
~ ll) t:, en
f""'t-

'-&lt;

:::1

•

ll)

¡;- ~- :;, S' "O

l

~

s·

~

~·

~i:l
!:l.

~~-

l

f

::!

¡:¡·

g&lt;¡gQ¡;.~
(t)
- · ~ (1)
&amp;'
~ gi g (") &lt;.
(1)

ll)

~

=

....,

(1)

1

=::. (1) en
- ·
S. ,..,.
- · o.o

"'pi::!

ll)ªC!:1(1).

[~ocnO...,.
~~ ~ §

*~ ª~ ~
&lt; . '&lt; ..,

Table 4.2
Multinominal logit 2003-2004
Informo! employment

f.

s

Public sector

Employer

Self-employed

Without pay

Unemployed

Inactive

Man

13403. .
(.0641922)
[I 143431]

- 2493554• ( 1031152)
[.779303]

7920747••·
( 1355725)
[2 207972]

1699946( 075975)
[I 185298]

• 0667076
(1235706)
[ 9354687]

1648315
(. 1052591)
[1179194]

• 9394299••·
( 0680743)
[.3908506]

Married

- 2309129••·
( 0653545)
[ 7938086]

1063348·( 1001353)
[l 112194]

3496961 - •
(.1238861)
(1 418636]

0691782
(.0731601)
[1 071627]

3100591-•
(.1209743)
[l 363506]

.4447951• (.1139979)
[.6409556]

3975055·( 066736)
[l 488108)

26-35

-.0027778
( 0724234)
[ 9972261]

4219397•( 1174755)
(1 524917)

1429459••·
( 186258)
(4 176438)

.8580667*••
( 0921129)
[2 358596)

.0166911
( 1351575)
(1 016831)

- 0064051
( 1241225)
[ 9936154)

0132522
( 0775561)
[1 01334)

36-45

1093551
( 0855584)
[1 115558)

8469724*. .
( 132261)
[2 332574)

1 919877••·
( 1957536)
[6 820121)

1.231443· · ·
( 1023956)
[3 42617]

.416:r749· · ·
( 1528015)
(1 516303)

2001683
( 1526348)
[1 221608]

3546639···
( 0898622)
(1 425701]

46-55

1023999
( 1092043)
[1 107826]

8938785••·
( 1600287)
[2 444593)

2 432474••·
(2106202)
(11 38701]

1466706••·
( 1210324)
(4 334932]

1 00456•··
( 1810748)
[2 730706)

3027238
( 1937034)
(1 353541)

1 027045••·
( 1097381)
[2 7928]

3379784••
( 1504771)
[140211]

1 060758•-( 221087)
(2 88856]

2 656349-·
( 2445:?03)
(14 24419]

1935741••·
( 1556116)
(6 929176]

2 097706••·
( 21761:?4)
(8 147461]

4764521•
( 2630868)
(l 610351)

2 115947••·
( 1450753)
[8 297438)

- 523567·· ·
( 1681234)

-2503935
( 327269)

[ 5924037)

[ 7784944]

- 3548177
( 2535207)
[ 7013013)

- 4062075••
( 1756248)
[ 6661719]

- 1979232
( 257252)
[ 8204329]

-.3906169
(.2860994)
[.6766393]

-.4822626·•·
( 1723505)
¡ 6173849 l

Age

56-65

ir.
a--...

[

?

l·

lI
......S·
8
:--,

~
,-..
.'&lt;&gt;

i-...

-

Education
Incomplete
PrimBJY

'O

�r

---

I

~-

'

•lz

N

o

Table 4.2 {continuation2
Multinominal logit 2003-2004
Infonnal employment Public sector

Employer

Self-employed

\\'..il!ulli!. pay

Unemployed

lnactiv e
-,802:?474•··
( 1651849)
[ 4483203]

Complete Primary

• 840885···
( \6\5412)
[ 4313286]

-0243154
( 3089737)
[ 9759778]

-4504748°
( 2434301)
[ 6373255]

- 6773404···
( 1688155)
[ 5079662]

- 3942854
( 2466515)
[ 6741616]

• 7773852°ºº
( 2758062)
[ 4596062]

Incomplete Secondary

-.8996849"º "
( \847673)
[ 4066978]

0449586
(3522767)
[l 045985]

- 6253745º º
(3\39048)
[ 535061]

- 7960135...
( 2021691)
[ 451 l'.?38]

• 8448205• ••
( 326978)
[ 4'.!96345]

• 6067105°
( 3\76012)
[ 545141'.l]

.9443374•( 1966189)
[ 3889372]

Complete SecondNy

-l.251588·( 164370\)
[ 2860501]

119'.l'.!54
( 3101343)
[l 126624]

-3740375
( 252358\)
[ 687951 l]

-919085-·
( \73548\)
[ 3988838]

-5105518ºº
( 25\7194)
[ 6001643]

-6746635..
( 2747439)
[ 5093278]

-1 086925°••
(. 1683068)
[ 33725'.l]

• 3078927
( 2857861)
( 7349942]

-5106979º
( 2983714)
16000767]

-824'.!97•( 1882995)
[ 4385432]

-694674°••
( 2597627)
( 4992372]

-6009115( 2774897)
( 5483116]

-9882492( 1705631)
t 3722278]

-.6623648° 0
( 2736743)
( 5\56305]

• 9908084º º"
( 1687471)
( 3712764]

00

Incomplete Upper
Secondary

-1 4'.!0595···
( 1857385)
[ 2415701]

4999741
(.3336024)
(1 648679]

• 0063101
( 2879705)
( 9937097]

-1 130225°
( 2050444)
131'.!9604]

Complete Upper
Secondary

-1.424967°0 •
( 1684653)
( 2405165]

5353066°
( 3091443)
(1 707972]

., 1739471
( 2582667)
[ 8403413]

-1 109943•• ·
( 1796176)
( 3195776]

9296877••·
( 304524)
[2 533718]

2601547
( 243364)
(1 29713\]

•1 069073°
( 1748991)
[ 3433267]

- 6847:?72••·
( 258209)
[ 5042278]

Informal Employment

2 926175···
( 0669322)
[18 65614]

173942°( 1543922)
[5 69404]

2 197798···
( 1714247)
[9 005166]

:? 745609···
( 1027163)
[15,5741]

2 S0764S•••
(2457423)
[12 27599]

1693734( 1409376)
[5.439757]

2 330342-( 0955303)
(10 28146]

l 934641°0 º
( 1510443)
[6 921556]

6728015-·
( 1429209)
(835 4868]

2 441038...
(251067)
[1148496]

:? 741:!9:?···

Public Sector

:? 347588· ··
( 4230985)
(10 46031]

2 :?18518···
( 23129)
[9 194248]

2 863074• ( 1518417)
[17 51529]

-1 452148· ··
( 1659877)
[ 234067]

Colleg e degree

00

'

i

~
e

l

~
o

";¡·
~

~-

~i:!
"ii1
ª'a·

l

f
¡:¡·

Labor cate¡:;ory l!revious year

( 1714905)
[15 52252]

Table 4.2 (continuation}
Multinominal logit 2003-2004
Infonnal e1nploymen1 Public sector

f..

Employer

Self-employed

~ pay

Unemployed

Inactiv e

2 372053• (,167539)
[10 71938]

2 250209- •
( 2716477)
[9 489718]

5 616081 - •
(, 1802121)
[274 8102]

4.37283- (, 1581038)
[79 26761]

4 273258(.3156596)
[71 75505]

2 14915(.2964243)
[8 577569]

2 495029-•
(.2088918)
[12 12209]

2 977643- ·
Self-employment (. 1094 113)
(19 64147]

2897158000
( 1819474)
(18 12256]

4 524843• ( 164623)
(92 28145]

5 49082· (.1195404)
(242 4558]

4 332364(,2492398)
[76 12401]

2 846125· · ·
(.1758146)
[17 22091]

375444• (, 1222085)
[42 7 1029]

2844849W ithout peym ent (.1960622)
[17 19897]

2 348123- •
( 3599089)
[10 46591]

4 086159- ( 3045688)
[59 51088]

4 356376•( 2081808)
(77 97401]

6 495209° 00
(.26919)
(661.9623]

2 199857**"
(.3373788)
(9 02372]

4118135• (.1891782)
(61 44454]

Employer

Unemployed

2 160395- ·
( 1129135)
(8 67456]

2 679134·•·
(.1836577)
(14 57246]

2.339923° **
(.2592491)
(10 38044]

2716213( 1527924)
(15 12295]

2 84597--•
( 3045455)
(17 21826]

2995811 ( 1527488)
(20 00158]

3 139553- •
(. 1245092)
[23 09355]

2 686553• (.1525367)
(14 68098]

2 626683•-(,2132109)
[13 82783]

3 684491•--

Inactive

2 54007·•·
( 0888057)
(12 68055]

4.016097• (.2259405)
[55 48413]

2 815168- •
(, 1392017)
[16 66261]

5 227348- •
(.0921762)
[186 2981]

(.1139906)
[39 82484]

[
['
~

?

1

¡·

lI
...s·

8
:"'

~
,-.

~

Household
- 2406196°•
(. 1166083)
[,7861406]

-2070892
( 1396738)
(,8129471]

- 2497451 . . .
( 0843404)
[ 7789994]

-2 3 l 3558° 0 0
( 1776901)
[.0989087]

-480839600 •
(. 1356735)
[ 6182641]

-1 14435800•
(.0835412)
[ 3184284]

- 1044743
% members over 65 ( 3004036)
[ 9007979]

6022129
( 4240661)
(1.826155]

- 7416206
( 5962135)
(,476341 3]

-0515407
(3375906)
[.949765]

· 9044664·
( 5190615)
[ 4047578]

- 1963177
( 4938199)
[.8217511]

- 2827827
( 3004301)
[ 7536836]

2839528°
% memben under 12 ( 1440132)
(1 32837]

0994479
( 2297827)
(110456 1]

1792917
( 2081896)
[1 19637]

114916
( 160593)
[1 121779]

-4308198
( 4132936)
[.649976]

2829398
( 2726587)
(1.327025]

-1403192-·
( 2222686)
[ 2458111]

Head

i,.

• 3316258°••
( 0755677)
( 7177559]

l

:::::

Ñ

�122 /

The Informal Sector in Mexico: Characteristics and Dynamics

-~"
"'"'"'
º"'"'
r-'..,_;.,.__,
- "
\O ("I 00

cor- -

.~.,..,.._

:

_..,..,
r-"'"'
P\
.., o"'
,· ....:, ......

Results 1991

,,...,
C"I

..

("1 - r - -

,

.~-

~g~

co - r¡;;; ~ ~

( ' I O\

~ ~~

- ,· oco
..._;,,.,__.

In categories regarding household, being head of the household reduced the probability ofbeing in other categories di:fferent from formal
employment. For the ratio of over 65 to members in a productive age,
no significant e:ffect can be established over probabilities, except for
those without payment, where the probability of being in that category
is reduced compared to formal employment. For the ratio of members
of the household under 12 to those in a productive age, this is only positive and significant for the informal employment group, but negative for
the inactive one. Having another member of the household with social
security from work decreases the probability of being in the informal
employment, employer, self-employed and without pay categories
compared to formal employment. This means that if someone else in
the household has social security at work, it is more probable that the
individual is in the formal employment category.
For regional controls, it was found that the north region reduces in a
significant way the probability of being in any category compared to the
formal sector. The central region reduces the probability of being in the
public sector, unemployed or inactive, while the south is only significant
in reducing the probability of unemployment.

-r- °'..,
""co
,,.,....,
O\...,..

C"l tr\ -

123

Within the categories individuals were five quarters back, the same
category where they currently are has a higher effect on the probability
of being in any category different from the reference, except informal
employment, where the main effect comes from being self-employed
before. The second most important effect usually comes from being
in the self-employed group, and before that one the category "without
payment". Self-employment is the category that introduces a noticeable
dynamics in the other categories, having a positive significant e:ffect on
the probability of being in other categories rather than formal employment.

..,,.• _,..-

:

Revista Perspeclivas Sociales I Social Perspeclives primaveralspring 2007. Vo/.9, Num. 11

.....,;.,__.

00 ' ' " " '

Table 4.3 shows the result for the third quarter in 1991 with individuals
who were observed since the third quarter in 1990.
Being a man reduces the probability of being in the public sector

�j

í _:;_i

og.s,~g

~

'""8~oe;
e; en ("I) ::l. ("I)
8.oS~o..

¡i

]§si.g
....., "O

~

oo-o¡;.

-

0

o's • ~("I)~

::10C1S-oo

=
s· g- . a
s
~
o- g
s

~

.....

~

l~
IS
...
;¡·

l3g"Q5-:§
("I) ~ - o.

¡g·

~º~ogS ::::1 • .....,

~

("I)

.....

-g_
s·
o'=.',~

.....

=
,.. ~ er s· s

("l)l::$t:d0"0'="'
~

("I)

("I)

s
~
-g_ s s·
º ei;:i. ~ "Oe
(Je¡ (Je¡

~
~

i:;·

a-

s 8.&amp;.o fl
~aº~~
........ s
("I)

("I)

§o. s·
g g
t:t&gt; .........
e:
en o
=
("l)=-ct
("I)
("I)

~

~

9 s.
o ~ (le¡º

"O

o- c:s
....

'ciO~o

.:=~

Table 4.3
Multinominal logit 2003-2004
lnfonn1l employmont

Public sector

8
en

("I)

~
.

"l"j

e; ....o

0--o
i::

O- o
,..

¡;. -o ....
~
("I)

!,

Employer

Self-employed

Without pay

Unemployed

Inactiv e

O 1437°

.03712-

l 03575•••

.3013679- •

1258618

1481047

•l 198245• • •

(O 0993)
[O 6898]

(02010)
[2 8112]

(.0962275)
[1 351707]

(, 1703257)
[1134125]

( 1764722)
[1159634]

( 0758059))
[ 3017232]

.O 1333°
( 0797)
[ 8751]

O 1399 · (O 0945)
[1 1502]

O 38::!8. .

(O 1632)
{14664]

2197091••
( 0873313)
[1 245714]

1955833
( 166544)
[1 21602]

-4153888( 2026015)
[ 6600836]

5340878- ·
( 0714524)
[1 705891]

26-35

O 0061
( 0857)
[1 0064]

04297 ...
(0.1083)
[1 5368]

14360• ..
(0 2447)
[4 2039]

6523519- ·
( 1099868)
[1 920051]

- 1100319
(. 1745224)
[ 8958056]

- 243319
( 2053572)
[ 7840214]

- 0714288
( 0821747)
[ 9310625]

36-45

O 1077
(0 1034)
[11137]

O8::!S6..•
(O 1242)
[2 2834]

19156(0 2564)
[61914]

l 01::!973- •
(, 1217635)
[2 753777]

5358198- •
(.202564)
[1 708849]

-6521551••
( 310843)
[ 5209219]

3243943( 0975099)
[1 383193]

46-55

O 1959
(O 1278)
[1 2164]

10363- ·
(0 1515)
[2 8189]

2 !764•··
(O 2707)
[91420]

1153271 00•
( 1404527)
[3 16854]

1164912( 2462'759)
[3 205641]

- 0279133
( 3481833)
[ 972472'1]

1173337( 1194848)
[3 232764]

O 2810°
(O 1686)
[1 3245]

O 9581••·
(O 2104)
[2 6069]

2475 1•(O 3059)
[118837]

1487235- •
( 1706247)
[4 424843]

2145638- ·
(2988511)
[8 547489]

-1243548
( 4916216)
[ 8830665]

2102426- •
( 1488007)
[8 186007]

-O 3348* 0
(O 1659)
[O 7154]

04070
(O '.l977)
[1 5023]

-O 1926
(0 317:?)
[O 8247]

- 424104 00
( 1669511)
[ 6543558]

- 3239114
( 3165842)
[ 7233143]

• 3394435
( 4572393)
[ 71'.l1666]

- 260642
( 1615828)
[ 7705567]

MBJTied

9

"'
¡.

( 0798)
[11541

Man

8

("I)

AJ:!

i

J
.....

[

1
l

I

s·

l)Q

8
~

~
,-.
~

56-65

f

.....

Education
Incomplete Primary

Ñ

u,

�j

¡.-~J

....
N
O'I

Table 4.3 ( continuation)
Multinominal logit 2003-2004
Public sector

Employer

Self-employed

:'Nj\h9utpay

Unemploy ed

Inactive

Complete Primary

-O 5970• •
(O 161J)
[ 550409]

O 321216
(O 28871)
[1 3788]

O0602
(O 3063)
[1 0620]

• 6245539·· ·
( 1627935)
[ 5355003]

- 2899847
( 3039101)
[ 748275]

-8930429**
(45 11611)
[ 409408]

-4071885•· ·
( 1566505)
[ 6655188]

Incomplete Secondruy

-O 6051 •••
(O 1963)
[O 5460]

798427••
(O n213)
[2 2220]

O 3127
(O 3726)
[1 3671]

• 7352079•··
( 2108914)
[ 4794058]

- 1540917
( 3971959)
[ 8571934]

- 2695767
( 5049765)
[ 76370:rl]

-.3279083°
( 1985577)
[ 720429]

Complete Secondary

-O 8943(0 1676)
[O 4088]

O 5219*
(O 2915)
[1 6852]

O 1435
(O 3193)
[1 1543]

-903601•• ·
( 172674)
[ 4051082]

-5701557"
( 3182133)
[ 5654374]

- 818931*
( 4484815)
[ 44090:rl]

-6819047••·
( 1622482)
[ 505653]

-O 8118••·
(0 1893)
[O 4440]

O 6033•
(O 3117)
[1 8282]

-O 1264
(O 3759)
[O 8812]

-1 078198···
( 2100542)
[ 3402079]

- 2962451
( 355739)
[ 7436051]

-4860207
( 471!742)
[ 6150691]

-4078772• •
( 182624)
[ 6650605]

~1 0112••·

(0 1758)
(O 3425]

O8335·-·
(O 29 15)
[B015]

04388
(O 3265)
(1 5509]

-9934341º**
( 1825335)
[ 3703029]

-41 19593
{ 3215768)
[ 6623512]

- 5320881
( 4481725)
[ 5S7m2J

• 5769:r78•••
( 1648429)
[ 5616211]

-O 9115•• ·
(O 1721)
(04019)

1 0383···
(O 2892)
p 8244]

O9375• (0 3096)
(2 5537]

- 9926435**•
( 1786203)
[ 370595]

• 5148065
( 332576)
[ 5976162)

-4591702
( 4443953)
[ 6318077]

-4272589-·
( 16633)
[ 6522947]

1 3094• • ·
(0 1905)
[3 7041]

1 455812•• ·
( 1078687)
[4 287965]

1 379322-•
( 2598976)
[3 972206]

1 006191*( 2275091)
[2 735163)

( 0981333)
[3 471207]

[6 6116)

O 8798...
(0 1396)
[2 4104]

O7609º""
(0 1293)
[2 1402]

3 8907••·
(O 1058)
[48 9466)

1 1809···
(O 2149)
[3 2576]

1 22121•..
( 1436612)
[3411903]

1074132•(3675579)
[2 927451)

( 2830378)
[3 459667)

lnfonnal cmployment

Incomplete Upper
Sccondary
Complete Upper
Secondary
College degree

'
;;l
"'

~
e,

3

!l..

~

s

"

;¡·

f~-

r~
a~-

l

f
¡;¡·

Labor cate2ory l!revious year
1 8888•••

Infonnal Employment (O OT/6)

Public Sector

1241172••·

1 244502• • ·

1 365473•··
( 119261 l)
[3 917576]

Table 4.3 (continuation)
Multinominal logit 2003-2004

""~~

Public sector

Employer

Self-employed

Withoutpay

Unemployed

Inactive

Employer

10782(O 1798)
[2.939S]

1 5143- •
(O 2082)
[4 5464]

3 8164••·
(O 1737)
[454404]

2 540719·•·
( 1495935)
[12.68879]

2 490773••·
(.4332993)
(12.07061]

7742863
( 6111054)
[2 169044]

1179639 ...
{ 2121529)
[3 2532]

1 4 903••·
(O 1525)
[4 3944]

2 5553• (O 1673)
[12 8754)

3 265903-

Self-Employmcnt

l S315**0
{O 1076)
(4 6254]

( 1036439)
[26 20375]

2 213625-•
( 2810443)
[9 148825)

1 2625:rl...
(.3083453)
[3 534343]

1 936095•{ 1147464)
[6 931627]

Without paymcnt

14229• •
(0.3230)
[4 1492]

20173- •
(O 3779)
[7 5182]

2 8045--•
(O 5299)
[16 519]

3 019291- •
(2989903)
[20 47677)

4 817182• ( 315237)
[123 6162)

1 505483. .
( 64 12422)
[4 506329]

3 059394( 2545801)
[21 31463]

Unemployed

1 2604-•
(O 2112)
[3 5268]

14507-•
(O 2897)
[4 2661]

1 3722••
(O 5389)
[39441]

1 721074• ( 2584943)
[5 590529]

986087
{ 6253818)
[2 680724]

2 135449••·
( 3238812)
[8 460843]

1 769354••·
{ 2073573)
[5 867062]

l 3601 - •

17000- •

1 7074- •

2 074775••·

2 471455••·

1 83 125- •

3 3284 6••·

(O 0961)
[3 8969)

(O 1238)
[5 4742]

(0 2224)
[5 5149]

( 1139817)
[7 962755]

{ 2165449)
(11 83967]

(.2030375)
[6 241684]

(0819341)
(27 89535]

Infonnal ,mploym, nt

Inactive

l¡·
[
'
[
~

?

l·

l

.f
j·
"'
8
N

Household

~

~

-0.3819°••
(O 0940)
[O 682S]

-O 3247(O 1131)
[07227]

% memben over 65

-O 3654
(O 3724)
[O 6938]

-O 2357 (O 4187)
[O 7899]

% manbersunder 12

O 0443
(0 1585)
(1 04S3]

O2352
(O 1943)
[l 2652]

Head

-O 0998*••

-2553925••
( 1041497)
[ 7746124]

-3 9367••·
( 365084)
[ 0195 112]

- 6950763•··
(.2543271)
[ 4990364]

-1411064( 0956443)
[ 2438838]

(O 7856)
[O 5959]

2868503
( 3948603)
[1 332225]

1331704
( 5571117)
[1 142445]

1711459
(76592)
[I 186664]

-1 0 1434••·
( 326732)
[ 3626418]

-O 4466"
{O 2373)
[O 6397]

- 1446657
( 1662225)
[ 8653115]

-1 225626•
{ 6546017)
[ 2935738]

-Ol n049
( 4735507)
[ 9829422]

-1 805081••·
(2539623)
[ 1644611]

(O 1980)
[O 9049]

-O 5175

J

::::

Ñ

-.J

�J28 / The Informal Sector in Mexiro: CharacJeristics anti Dynomics

Revista Perspectivas Sociales / Social Perspectives primavero/spring 2007. Vo/.9, Num. I /

129

Education levels generally reduce the probability ofbeing in a category different from formal employment, as the individual moves on in
those levels. The exception is found in the public sector, where the more
educated increases the probability of being in this category compared
to formal employment. However, for the employer category, education
levels are not significant in the highest, while for the group without
payment only complete mid-school is significant, and for the case of
unemployed complete elementary and mid-school are significant.
As for the position of the previous year observed in 1992, the main
effect in all categories comes from the category where the individual was
the previous year. However, different from the previously analyzed years,
the main dynamics comes from the category without payment, while the
same dynamics are introduced by the self-employment category for the
years 1996 y 2004.
Being head of household reduces the chances of being in a category different from formal employment. Tbe variable of the ratio of
individuals over 65 to those in a productive age in the household is only
significant for the inactive group, where the probability of being in this
sector compared to formal employment is reduced. Toe variable of the
ratio of under 12 to those in a productive age is only significant for the
categories without payment and inactive, where the probability of being
in those sectors is reduced compared to formal employment. The variable of other members of the household with social security from work
is significant for the informal employment, employer, self-employed
and without payment groups, where the probability of being in those
categories compared to formal employment is reduced.

.... .......,.......

Variable for the north region is only significative to reduce the probability of being in the informal employment, public sector and unemployed categories. Toe center variable is only significative to reduce the
probability in the informal employment, public sector and unemployed
categories. The southem region variable is significative to reduce the
probabilities of informal employment and unemployment.

General Findings

�130 / The Informal Sector in Mexico: Characteristics and Dynamics

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vo/.9, Num. J /

From the two analyses in this section, we can get two important conclusions. First, there seems to be a change in the labor dynamics around
1994/95. Before those years, it seems like the labor dynamics carne from
the workers in the category without payment. After that period, the main
source of dynamics among sectors comes from the self-employment
category.

are relevant to consider that could be more attractive in the categories
used.

Wage Premia and Income Levels
In this section, we develop a quantile regression, ora regression by level
of income on the wage logarithm per hour based on a number of factors.
Toe use of this type of analysis by quantiles allows us to leam how wage
premia vary to education, and to the other labor categories that are used
as part ofthis work in regards to a specific income leve! ofthe employee.
This means we can leam about the wage premia received by a worker
in informal employment based on a set of characteristics, whether the
individual earns a low, medium or high income.

Age has an important role on the decision to join different labor
categories. As we move forward in age groups, there is less probability
of being in the formal employment sector generally. This has implications on the future of retirement programs. For instance, it was found
that the younger workers have a higher probability ofbeing in the formal
employment category, but as they grow older they change to a job that
has no social security, so they probably will not meet the requirements
to rate and access a retirement in the future. We can also observe the
incentives that younger workers have to increase their human capital
if future perspectives do not look promising. As for education levels,
the higher education is, the more probable it is to find the worker in the
formal employment or public sector categories.

................

In the variables regarding household, there is no big relevance as for
the number of individuals over 65, although there is evidence regarding
those under 12 in the household reducing the probability ofbeing in the
formal sector. Nevertheless, we noticed a strong effect in cases where
another member of the household has social security to have a higher
probability ofbeing in a formal job, which is congruent with other studies
done for Latinamerica (See for instance Auerbach, Genoni and Pagés,
2005). This indicates a possible use of the social household networks
to have more information on the labor market, since there it is possible
to find a high quest for sorne given employments through relatives, and
results in something productive. It has been documented that those individuals who are looking for a job through relatives usually get higher
job offers than those who use different sources of information (see Calvó
and Ionnannis, 2005).
Having analyzed all characteristics of workers within the labor dynamics, it is important to wonder ifthose wage rewards between formal
and informal workers [the different labor categories used in this book]

131

Koenker and Bassett (1978) proposed this type of regressions
given the fact that the Ordinary Least Squares (OLS) are based only on
the measure of the conditional distribution of the dependent variable.
Quantiles allow us to leam the effects of the independent variables on
the conditioned distribution, together with the media (Koenker, 2005).
Quantile Regression
Aregression of the OLS is based on the mean of the conditional distribution of the dependent variable used in the analysis. This proxy assumes
that possible differences in terms ofthe impact ofthe exogenous variables
together with the conditional distribution are important.
Nevertheless, this could mean insufficiencies in sorne research
agendas. If exogenous variables influence parameters of the conditional
distribution ofthe dependent variables in others more than the mean, then
an analysis that ignores this possibility would be seriously weakened.
(See Koenker and Bassett 1978). Unlike OLS, the regression models by
quantiles allow a wide characterization of the conditional distributions
of the dependent variable.3

3

See Abadie et al. (2002) for a recent extention on quantile regressions, considering
instrumental variables.

�132 /

The Informal Sector in Mexico: Characteristics and Dynamics

Revista Perspectivas Sociales / Social Perspectives primavera/spring 2007. 10/.9, Num. / /

Given a wages equation, the regression model by quantiles could be
expressed like this:
In w, .. xifJs + ua When Quants(ln Wi I xi) = xifJs

(1)

Where x¡ is the vector of exogenous variables and fJs is the vector of
the parameters. (In wlx) denotes the 8 vo. conditional quantile of In w
given by x. la 8 va. Quantile regression, O&lt; 8 &lt;1, is defined as the solution to the problem:
(2)
This is expressed as such:

133

Toe dependent variable is the logarithm of the labor income per
hour. Toe independent variables being included are education (complete
and/or incomplete elementary school, middle-school, high-school, and
college) working experience and its squared, married, head ofhousehold,
male, labor occupational groups, (informal employment, governmental,
employer, self-employed) as well as controls of regions (north, center
and south regions).
In the following subsections, we will present the results for employees that have a working income in the age range of 18 to 65 years
old. We will obtain results for the income function using the quantile
regression, where common errors are calculated using the bootstrapping
method. We will show results for income quantiles 10, 25, 50, 75, and
90 for the mentioned age groups.

(3)

Results
Where

ps(E) is

the control function defined as po(s)-9,if e .i: O or

pe(e) • (8 -l)E ifs ª 0

2004 Results

This problem &lt;loes not have an explicit form, but it could be solved
using linear programming methods .. Standard errors could be obtained
through the bootstrap methods. (see Koenker, 2005).

Table 5.1 presents the results for the urban part of the ENET 2004, third
quarter of the year, in a quantile regression of the real labor income per
hour. Toe results must be read as a wage premia for having a particular
skill (explainable variables) in a determined place of the labor of the
worker (income quantile)

Toe minimum absolute deviation (MAD) estimated in pis a particular case in this setting. This is obtained selecting 9 =0.5 (regression of
the median). Toe first quantile is obtained selecting 8=0.25 and so forth
similarly. When there is an increase in 0 from Oto l, a sign of the whole
distribution of y, conditional to x.

Data and Variables
Toe data is obtained from the micro database of the ENEU and the urban part of the ENET. For this particular case, we will not be using the
individual panel, but rather the total observations for the third quarter
in 2004, 1996, and 1991. Toe categories without payment, unemployed
and inactive are not included either, since they do not mak:e an income
and thus they cannot be part of an income function.

�134

/ The Informal Sector in Mexico: Choracteristics and Dynamics

Revista Perspectivas Sociales/ Social Perspectives primavera/spring 2()()7. Vo/.9, Num. / /

Table 5.1
Regression Results for Income Quantiles 2004
Quantile
Variable

Incomplete
Primary
Complete Primary
Incomplete
Seconda,y
Complete
Seconda,y
Incomplete Upper
Seconda,y
Complete
Seconda,y
College

Mamed
íñfonnal
employment

...

Govemment

F.mployer

'\

Self-employment
Head

North
Center
South
Man

R2

1i-..11-..
"' .........

(.0070435)
-.2199963°•
(.0071431)
.1892912*º
(.0086998)
. 133675*º
(.0199555)
__4973430•
(.0138877)
.071326••·
(.0086219)
. 1002312•0
(.0138612)
-.0013398
(.0142959)
-.2077129*..
(.0157597)
.0623962*º
(.007271)

.25
.0204382
(.01496*)
.0945392•0
(.0152091)
. 1289864•..
(.0181606)
. 1479025***
(.0159408)
.2299767*••
(.0170138)
.3000898••·
(.0168284)
.6920182•0
(.0167268)
.0788723h•
(.005846)
-.1790926*º
(.0056355)
.2499325*'*
(.0069618)
.277602...
(.0130429)
-.2452206* ..
(.0088229)
.0668863••·
(.0059444)
.103149*"
(.0104258)
.0066643
(.0103409)
-.1934692••·
(.0112846)
.0796126***
(.0055834)

0.1385

0.1422

.1
.0511846**
(.0265233)
.1491348•h
(.0256215)
. 1723762°•
(.0295809)
.1858011 ...
(.0256208)
.2530756***
(.0283632)
.3318542*••
(.0262393)
.6341614°•
(.026138)

.055976'ith

In Figure 5.1 wage premia or returns to the estimated educational
levels in table 5.1 are shown4 .

.0302701••
(.0117865)
. 1063048*º
(.0115348)
.1633982*º
(.0152688)
.1830439••·
(.0114809)
.2910544••·
(.0135515)
.3766218***
(.0117658)
.8869538*º
(.0134109)
.0785801 ...
(.0051647)
-.122985'7tº
(.0048342)
.277089'**
(.0069683)
.372789º*
(.0124937)
-.0382427***
(.0069408)
.0604478••·
(.0055631)
.1139433*º
(.0075823)

.75
.0481907*••
(.0146283)
.1234635...
(.0136753)
.2097974••·
(.0172899)
.2344791••·
(.0139388)
.3706626*"*
(.0156332)
.500191••·
(.014922)
1.099131...
(.0161795)
.0834417***
(.0059051)
-.0663344*..
(.0063538)
.2687495***
(.0086934)
.4995041...
(.0136418)
.129792***
(.0074375)
.0680362***
(.0063712)
. 1246903'*•
(.0091802)

.01os1o,

.0!790l9h

(.007225)
-.162836••·
(.0088197)
.096692***
(.005026)

(.0093 147)
-.1231185•..
(.0103351)
.0975305***
(.0057426)

0.1752

0.2164

.5

135

.,
.071652***
(.0199309)
.1676048º*
(.0191575)
.2817784•..
(.024478)
.3080247•..
(.0192494)
.5007157•..
(.0252299)
.6786236*º
(.020911)
1.315767...
(.022214)
.105596*..
(.0083876)
.005781
(.0085511)
.2334153*'*
(.0101951)
.6688364...
(.0199851)
.2839413•0
(.0117071)
.076841*..
(.0090529)
.1262436*"
(.0117201)
-.00621 , ...
(.0121933)
-.1263096•..
(.0136491)

.0712728...

Premio salarial por niveles educativos 2004
20

18
16

- + -primaria inco"l)leta

14

~maria completa

12

_._secundaria incompleta

10

--H--seetJndaria completa

8

--ll-i&gt;'epa · ~ • t a

6

-+-P&lt;epa completa

4

ofesional

2

o
0.1

0.25

0.5

0.75

0.9

Cuan111es (nivel) de Ingreso

Note: The rates are calculated comparing the previous educational leve!.

From the chart, we can observe that returns to school tend to be
higher when the income level of the employee is higher. Toe returns
to the professional level increase the most as the leve) of income also
increases. These are followed by the high school levels both complete
and incomplete, which have similar levels to one another.

(.0084942)
0.2188

N= 100044. Standard errors in parentheses. Bootstrapping method is used. Significance levels 1, 5,
and 10% respectively. Base categories: formal wage jobs, Capital region: female

Figure 5.1

For the occupation categories, graph 5.2 shows the wage premia for
occupations based in calculations made in chart 5.1, where the comparison base is the category of formal salaried position. We can observe in
general that the categories improve their performance as the employee
raises hís/her income level.

~ Calculated by dividing the chang¡ in the mid point of the year previous to the study
m education leve/ over the change ofcoefficient obtained in the regression ofschooling
and the following downwards.

�136

/ The Informal Sector in Mexico: Choracteristics and Dynamics

Revista Perspectivas Sociales / Social Perspectives primaveralspring 2007. Vol.9, Num. I /

Figure 5.2
Premio salarial por ocupación 2004

__.,_Asalanado infoonal

_._Gobierno
_._Patrón
- Autoen1)1eado

137

in the mid-range levels, it tends to decrease slightly in the upper-levels.
For the regions variable, if an individual works in the northern region he
has a positive wage premia over working in the capital city area (Mexico
City and Metropolitan Area). This premia could range between 10 and
12 percent as the work.ing income increases. Toe mid-region does not
have a significantly different premia from the country's capital in the
upper-income levels. For the southem region, the wage premia is negative at all levels, and it even decreases as the income increases. This is,
for a worker in the southem region compared to a worker with similar
characteristics in the Capital, the wage premia is negative and even larger
if the worker is in the lower income levels.

1996 Results

--

0.1

0.25

0.5

0 .75

0.9

Cuantiles (niveles) de Ingreso

Source: Data based on table 5.1 Comparison category: formal employment.

Individuals working in informal employment commonly receive a
negative wage premia compared to individuals work.ing in formal employment. Although their premia is increased, it is not until the highest
income levels where they receive a similar premia to the ones received
in formal employment. Toe self-employed individual receives a negative
wage premia (in comparison to people in formal employment) until they
reach the mid-range income levels, after that, their premia are comparable
in size.

.. ,....... ......... ,

For govemment-employed individuals, the wage premia are positive
throughout the income curve. They tend to increase in the mid-range levels and start decreasing slightly in the upper-levels. Toe employer offers
the highest premia compared to formal employment in the market. These
premia are always positive throughout the working income curve and in
the upper-income levels; they are around 60 percent ofthe premia.
Looking back at table 5.l, we found that the married variable has a
positive sign and it increases based on the income levels. Toe head of
household variable is also positive in al_la levels. Men in this category
have a positive wage premia over women and even though it increases

Table 5.2 shows the results for the regression by income levels using
the third quarter of the year in ENEU 1996 for the real labor income per
hour as a dependent variable.

�138 I The Jnfonnal Sector in Mexicc: CharacJeristics and Dynamics

Revista Penpeclivas Sociales / Social Perspectives primaveralspring 2007. Vol 9, Nran. J /

Table 5.2
Regression Results for lncome Quantiles 1996
Quantile

high-school) grow the fastest as the level of income of the worker also
increases, in contrast to the lower educational levels.

Variable
Incomplete

Primary
Complete Primary
Incomplete
Secondary
Complete
Secoodary
Incomplete Upper
Secondary
Complete Upper
Secoodary

College
Manied

..._,

Informal
employmmt
Govemmmt
Fmployer
Self-employmeot

Head
North
Ceoter
South

Man
Worl&lt;iog
Experieoce

Workiog
Experieoce1
Constaot

Rl

.........

.1
. 1122551•••
(.0193429)
.1935193...
(.0190364)
. 2293548••·
(.024222)
.3188051...
(.0186295)
. 3733448...
(.0210376)
. 5161528...
(.0192422)
.8227605...
(.020362)
.0686138•. .
(.0059136)
-.2657218°•
(.0062376)
. 2805529...
(.0084216)
.1697128*••
(.0169189)
-.3331458...
(.0098688)
.0837167••·
(.0071418)
-.049037*••
(.0087918)
-.1557438••·
(.009551)
-.2297399"..
(.Olll987)
.0280003•..
(.006752Z)
. 0217186*..
(.0009291)
-.0003885* ..
(.0000187)
1.368827*••
(.0227383)
0.1571

.25
. 0779013••·
(.0155775)
. 1607395••·
(.0151512)
. 222497...
(.0171238)
.2923388...
(.0158812)
. 3803345*. .
(.017253Z)
.5263087*. .
(.0154924)
. 933857••·
(.0161877)
.0866623••·
(.0043049)
· .2315485••·
(.0048499)
.3168207••·
(.0061455)
. 2686584••·
(.012273)
· .1730801*. .
(.0064)
. 0818733*. .
(.0053745)
-.0029008
(.0074481)
-.1184664••·
(.007536)
· .2031403••·
(.0077039)
. 0311422...
(.0055246)
.0232724...
(.000622)
·.0003828" ..
(.0000127)
1.562938••·
(.0187221)
0.1911

.5
.0767728...
(.0133274)
.169556••·
(.013042Z)
.2560976...
(.0145982)
.330222••·
(.0131502)
.4432641 ...
(.0152478)
.618564• ..
(.013649Z)
1.151073•..
(.0147181)
.0974822••·
(.0044044)
-.2105107*••
(.00497:?}
.3018258*..
(.0058275)
.3576882*..
(.0118846)
-.0570363••·
(.0060364)
.0724723•..
(.0054951)
.0271821••·
(.0072134)
-.1066489••·
(.0073342)
-.1940708• •·
(.0081512)
.0300351•••

(.0046499)
.0254699...
(.0006044)
-.0003789* ..
(.0000118)
1.760777*••
(.0157221)
0.2402

.75
.1013566••·
(.0130383)
.23062••·
(.0127941)
.3409061••·
(.014364Z)
.4376044 ...
(.0128849)
.6009575•..
(.0170523)
.8121152••·
(.014391:?}
1.435186• 0
(.0139282)
.1046407••·
(.0061323)
-.164419••·
(.0058265)
.233858••·
(.0066923)
.5038049••·
(.0162642)
.0521786* ..
(.0077985)
.0718272* ..
(.0064333)
.0618053• ..
(.0100186)
·- 1011695••·

(.0098389)
-.1730474••·
{-0109776)
. 0202127*••

(.0058695)
.0283686••·
(.0007813)
-.0003771••·
(.0000148)

1.901385• ..
{-0192232)
0.2760

.9
.1579764...
(.0172386)
.3145682...
(.0175479)
.4583621...
(.0219159)
.584766...
(.0198589)

.8054488••·
(.0246721)
1.066888...
(.0207088)
1.69914••·

Chart 5.3
Premio salarial por niveles educativos 1996
20
18
16
14

-+- primana '""""1)1eta

12

--primana con.,re1a
..,._ secundana ~ • t a

10

~

-.1900191*••
(.0145897)
.0156223..
(.0076389)
.029725 ...
(.0009204)
-.0003376••·
(.0000189)
2.019902••·
(.0263856)
0.2646

N= 117699. Standard Errors in pareotheses. Bootstrapping method is used. Sigoificaoce levels 1,
5 aod 10% respeetively. Base category: no schooling; Formal salaried position; Capital region;
female.

Table 5.3 shows retums to education by levels and they tend to be
increasing if the income (quantile) level increases. Toe professional
category has the highest retums, although they are very similar in the
last two income levels. Toe highest educational levels (professionals and

-eo&lt;!l)leta

- -prepa ~ e t a

(.0199884)
.1319679• 0
(.0077828)
-.0749106••·
(.0090122)
.1464727*••
(.0084852)
.6580552*º
(.0211757)
.1931023••·
(.0129109)
.083737*••
(.0088078)
.0810747*••
(.0125451)
-.1286197*••
(.0125078)

139

- - -prepa con1)1eta

6

profes,onal

2

o
0.1

02 5

05

0.75

09

Cuan111es (nivel) de Ingreso

Note: Toe rates are ealculated eomparing the previous level of edueation.

Chart 5.4 shows the wage premia by labor categories in 1996 and they
are based on calculations in table 5.2. With the exception of government
employees, the other categories have wage premia that increase as the
working income curve also increases.

�140

/ The Informal Sector in Mexico: Characteristics oml Dynamics

Revista Perspectivas Sociales I Social Perspectwes primaveralspring 2007. Vo/.9, Num. / /

Graph 5.4
Premio salarial por ocupación 1996

- . -Asalariado informal

---Gobierno
~ Patrón

-

141

income. Men have a positive premia compared to women, although it
tends to reduce slightly in the higher income levels. The northern region
gives a negative wage premia compared to the Capital if the worker is
in the lower income Ievels, changing into a positive premia once the
income starts growing. If the worker is in the mid-region, he will have,
ceteris panous, a negative premia compared to a similar worker in Mexico
City. For the southem region, the premia is negative and significant at
all levels of income, although it tends to decrease slightly in the upper
income levels.

Autoem eado

Results 1991
Table 5.3 shows the results for the quantile regression using the third
quarter in 1991.

..........

0.1

0.25

0.5

0.75

0.9

Cuantiles (niveles} de ingreso

Source: Data based oo table 5.2. Comparisoo category: formal salaried position.

For this year, we have in chart 5.4 that individuals in informal
employment have a negative premia in the labor income curve. Even
though this negative premia is limited to the highest levels of income,
in general it is significantly lower compared to formal employment. The
self-employed workers have a negative premia compared to the formal
salaried individuals until the mid-range leve1, after that, the premia turns
into a positive one.
For the government-employed category, chart 5.4 shows a positive
premia in the working income curve, which tends to increase slightly
toward the mid-range income levels and decreases approximately half
toward the upper-levels. The employer category has the highest wage
premia compared to formal employment just as it turned out for 2004
previously shown. In the lower income levels, the largest wage premia
is given by the government sector.
For the married, the premia is positive and it increases slightly as the
curve for working income advances. The heads of household also have
a positive wage premia although it is the same throughout the curve of

Table 5.3
Regression Results for Income Quantile 1991
Cuantil
Variable
Incomplete
Primary
Complete Primary

.1

.0551687**
(.0267286)
.1237991 •••
(.0274932)
Incomplete
.1855255•••
Secondary
(.0298567)
Complete
.2182557*••
Secondary
{.0287367)
Incomplete Upper .247231**•
Secondary
(.0309723)
Complete Upper
.396267**•
Secondary
(.0299785)
College
.6020031• • •
(.0312218}
Manied
.0823932...
(.0090953)
Infonnal
-.1216903*..
employment
(.0082643)
Govemment
.1333582***
.0111906
Employer
.2889954**•
(.0260289)
Self-employment -. 1030161••·
(.0124856)
Head
.0441012••·
{.0088653)
North
.0671651• • •
(.0091485)

.25
.0633283••·
(.0146187)
.1193638•• ·
(.0140155}
.2028266*..
(.0166813)
.2422491*..
(.0160813)
.2853215***
(.0163914)
.4617895•• ·
(.0 163283)
.7455765***
(.0175419)
.0818452• • ·
(.0073197)
-.0924429••·
(.0083655)
.1563353*..
(.0089152)
.4279039••·
(.0211014)
.0437407*••
(.0102258)
.0724099••·
(.0072246)
.0933573••·
(.0078559)

.s
.0556959• • ·
(.0202473)
.1380245*..
(.0189419)
.1983221...
(.0224715)
.2790569••·
(.0204858)
.3547888•• ·
(.0239595)
.5512295•••
(.0214404)
.944523• •·
(.0219422)
.1120955••·
(.0083919)
-.0511854••·
(.0085879)
.1113794••·
(.008792)
.545495*..
(.0214468)
.151444*..
(.0110676)
.0683675••·
(.0085853}
.1194034**•
(.0090717)

.75
.0896135••·
(.0202994)
.1942556...
(.0199053)
.2702281• •·
(.0230815)
.3844345• • ·
(.0211764)
.5083135••·
(.02598)
.7096411 • ••
(.0221647}
1.196042•• ·
(.0223244)
.1187584••·
(.0098344)
.0040867
(.0109363)
.0324234***
(.0105753}
.6308854***
(.019615)
.2172464••·
(.0131751)
.0803049••·
(.0100242)
.1311516•• ·
(.011249)

.9

.1325923••·
(.0274726)
.2917048••·
(.0279492)
.3757836***
(.0335228)
.5214944••·
(.0304094)
.6979481•••
(.0327972)
.8842974••·
(.0310439)
1.451293••·
(.0302028)
.1307988• •·
(.014494)
.1149119••·
(.0136031)
-.0052923
(.0145576)
.7766481...
(.0257003)
.3178652••·
(.0167693)
.0829771...
(.0139027)
.0847959••·
(.0174425)

�142 / The Informal Sector in Mexico: Characteristics anti Dynamics

-.0015701
(.0096832)
-.1195821•..
(.0168307)
.0928302...
(.0078159)
.0164481• 0
(.0011483)
-.0003104• 0
(.0000216)
1.723015...
(.031586)
0.0960

CeniaSouth

Man
Working
Experieoce
Working
Experience'
Constan!

R,

.0708555...
(.0091711)
-.1859325• 0
(.0147673)
.085109• 0
(.0075597)
.0230506• 0
(.0009473
-.0003'rº
(.0000175)
2.035036...
(.023684)
0.1575

. 0360782••·
(.0088733)
-.1420149...
(.0141396)
.0819983••·
(.006441)
.0183565••·
(.0008857)
-.0003189...
(.0000163)
1.873853°•
(.0195912)
0.1247

Revista Perspectivas Sociales/ Social Perspectives primavera/spring 2()()7. Vol.9, Num. I /

.0640071 ...
(.0112336)
-.2544137'..
(.0200547)
.085529••·
(.0088772)
.027509• 0
(.0011634)
-.0003982• 0
(.0000223)
2.211142• 0
(.0260835)
0.1922

-.0018299
(.0184506)
-.3056093• 0
(.0281755)
.0928522••·
(.0126079)
.0317108...
(.0016531)
-.0004142*º
(.0000332)
2.378112...
(.03677)
0.2155

143

The wage premia for labor categories are shown in figure 5.6. With
the exception of the government category, in ali other categories there
are growing premia as the income curve advances .
Figure 5.6
Premio salarial por ocupación 1991
90
80

N= 50709. Standard Errors in pareotheses. Bootstrapping method is used. • 0 ,•• , • Signficance
levels at 1, 5 aod 10"/o respectively. Base category: no schooling; formal employmeot; Capital
regioo; female.

70
60

50

- -Asalariado onformal

Toe returns to education by levels shown in Figure 5.5 are growing with the quantile, although for the high school category it tends to
decrease very slightly. Once more, the highest education levels tend to
grow in their wage premia faster than in the lower education levels. For
the lower income levels, the highest wage premia are in the high school
category (complete), as for the highest income levels the professional
levels offer a larger wage premia.

&lt;40

- -Gobierno

30

- - Patrón
~

20

Autoem

ado

10

o
-10
-20

0.1

0.25

0.5

0.75

0.9

Cuantiles (niveles) de ingreso

Source: Calculations are based on figure 5.3. Comparison category: formal

Figure 5.5

occupied.
Premio salarial por niveles educativos 1991
18

16
14
12
10

--+-,l)rimana ~
8

~manacon'C)leta

.....secundana ,ncompieta

6

--M--5"'Undana completa
4

Informal employment shows a negative wage premia in the lower
levels and it is not until quantile 75 that it evens formal employment. It
is significantly different and positive in the higher income group. For the
self-employed, the premia is negative for the lower income level only,
turning into a positive for ali the other quantiles. This is quite different
compared to the other years analyzed in this report, in which the midrange income group is where the premia turns positive.

~ l'ICOIT4)leta

-

2

epacoo1)1eta
ofesoonal

o
O1

025

0.5

075

09

c:u.,111es (nlveles) de Ingreso

Note: The rates are calculated in base to the previous education level.

For those working for the government, based on chart 5 .6, the premia
is positive, although it is only slightly different to zero and not significant
statistically speaking from the base of formal employment in groups in
the upper income levels. Toe performance of government workers is the
lowest and decreases faster than in the other years, 2004 and 1996. In the
case of the employer category, the tendency for the previously analyzed

�144

/

The lnfomu,f Sector in Mexico: Choracteristics amiDynamics

years persists, being positive and growing steadily. This is the highest
yield from the labor categories.
Just the same as previous years, the married, head of household and
male variables all have positive premia. Toe northem region shows a
positive premia in comparison to the workers from Mexico City, while
the southern region reflects a negative premia. For the mid-region, the
premia are negative at both ends of the curve although not very significant. Meanwhile, the premia are more signi:ficant and positive for the
mid-range income levels.
General Findings

...__

From the analysis shown in this section, we can infer that returns to
education levels are higher when the worker is at a higher income leve!.
After 1996, it seems like returns to lower education levels are reduced
compared to the previous years, while the highest levels increase slightly.
The effect seems connected to the increase in informal activities which
causes a drop in the number of retums and an inefficient allocation of
skills especially in the lower levels of education. (see Rodríguez-Oreggia, 2005).
Employer and government activities present the highest wage premia, while informal employment (no social security) have negative wage
premia ifcompared to formal employment. Just the same, self-employed
individuals have a negative wage premia (compared to formal salaried
positions) if they are in the lower income levels, which tends to change
once in the upper income levels.
As for informal employment, maybe the market &lt;loes not offer a
different job altemative, and the same for self-employment in the lower
income levels. For the self-employed in the upper income levels, however, the market offers an altemative in this sector, where they receive
a larger wage premia. Perhaps a focal point in terms of better working
condition policies could be the integration of these groups (informal
employment and self-employment in the lower income levels), which
will be considered in the following section.

Revista Perypectivas Sociales / Social Penpeclives primaveralspring 2007. Vo/.9, Num. f /

145

Conclusions
This study aims to analyze the dynamics of the labor market taking as
reference the informal sector of employment in different points in time.
Especially, changes have been determined between labor sectors using
transition matrices to determine labor mobility, as well as the socio-demographic and labor historical effects than have taken place in decision
of being in a specific sector, and the proportionate returns in sector by
labor income.
Toe contribution of this study is clearly established in the understanding ofthe dynamics followed by the informal sector and compared to the
formal one. Toe relevance ofthe analysis is understood in the sense that
a great part of the market takes place in the informal sector, diverting
resources and skills to activities with little impact on productivity and
growth ofthe country. Additionally, workers in the informal sector are not
protected in terrns of social benefits and their addition to the formal sector
becomes relevant to policy making issues in the country. The understanding ofthe dynamics of the informality stated in this study is also relevant
for poverty fight policies, since poor families get their income almost
exclusively from the labor market, generally from the informal sector.
From the transition matrices calculated, we can learn there is lirnited
labor mobility between categories, which seems to happen mainly among
the same informal categories (without social security). The less educated
have a higher tendency to move to the informal sector if their income
levels are low, and so it happens with self-employed. Additional to lower
education, these groups are known for a higher proportion of children
under twelve at home and located in groups of older age. The dynamics
of these informal groups with a salary and self-employed is originated
mainly from the fact of staying in the same informal category, but having
strong movements coming from those without a salary or unemployed.
This mobility is limited to informal categories within workers who
are already located in these categories and &lt;loes not allow an adjustment
to labor offer, which leads to a vicious cycle of informality in these
segments, taking it into a trap for individuals with jobs that offer lower
premia for skills.

�146 / 1ñe Informal Sector in Mexico: Characteristics and Dynamics

Revista Perspectivas Sociales/ Social Perspectives primavera/spring 2007. Vo/.9, Num. / /

Toe mobility mentioned above makes us think, first of all, that it is
easier to enter the informal sector, and secondly, that there are barriers to
enter the formal sector. Those barriers are mostly derived from regulations
that mean a higher cost of employing in the formal sector (with social
security),5 while the other part comes from a regulation framework tbat
does not allow a broader creation of jobs (see Banco Mundial, 2004a).
If integration policies from the informal to the formal sector are to be
applied, there should be a coordination with the regulation framework
and suggest improvements.

but in getting the jobs in which temporary learning and formality are exchanged to lower wages. In this case, labor policies focused on the most
vulnerable groups to stay in informal jobs (less educated, older), cannot
be non coordinated from those implemented to create small business,
where apparently there are incentives to stay in the informality, without
training nor incentives to acquire more skills.

0n the other hand, the limited mobility shown in the previous analysis
is higher among informal categories, also derived from the access to sorne
resources tbat can be necessary for a higher mobility to formal jobs (with
a salary or self-employed, where wage premia for sucb characteristics
are higher), where the resources considered are education, training and
access to capital.
A basic requirement to have a higher mobility to formal sectors
derives from equal opportunities to access education. Evidence in this
paper indicates there is indeed a direct impact of education on mobility between labor categories, especially to the formal one. However,
the distribution of education in general (not accounting for quality) is
still uneven in the country, especially in higher grades of education. In
fact, distribution has a regressive effect on higher levels, i.e. families
with bigher incomes take the higher benefits (see López-Acevedo and
Salinas, 2000 and 2000a). These limitations will certainly keep affecting
tbe structure of limited mobility in the Mexican labor market for sorne
generations if labor policies are not coordinated with education policies.
Youngsters, as it was shown, seem to find a formaljob more easily
tban adult workers, who usually find opportunities in the informal sector.
lf we link this to tbe fact that the Mexican labor market develops mainly
in small or micro enterprises, it seems lik:e the interest of companies is
not given mainly by the creating of consistent skills for those companies,
5 For instance:

Garro, Meléndez and Rodriguez-Oreggia (20O5)find that there is an increase offormal jobs related to diminishing contributions to social security in the 1997
reform, but such increase in too little compared to the size ofthe total labor force.

147

Finally, this study has sbown there are family nets that certainly have
an impact on individuals obtaining a formal job, especially if another
member of the family has already got a job of this kind. Funkhouser
(1997) previously pointed that, for Guatemala, the decision of labor offer and hence labor mobility, are partly based on the family, vicinity and
common networks. Socialization channels of individuals in our country
occur through home and, as stated in this study, influence the limited
labor mobility of workers.

�148

/ 7ñe Informal Sector in Mexico: Characteristics and Dynamics

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�152

/ The Informal Sector in Mexico: Characteristics and Dynamics

Appendix

Transition Matrix 2003-2004. Age 46-55
Informal
lnfonnal

Transition Matrix 2003-2004. Ages 18-25

11.69

69.58

2. 09

0.19

1.62

0.29

4 .37

10.17

100

6.09
9.68
27.14

7.11

61.51

6.45
6.53
31.94

0.00
1.01
1.90

12.69
9.68

?.28

1.02
29.03
34.17
4 .18

3.55

3.23
3.52

0.00
35.48
1.01
0 .76

2.03

6A5

29.66

100
100
100
100

4 .18
2.24
4 .36

0.42
0,08
0.44

S.02
2.03
4.25

0.84
3.11
3.98

IS.90
3.57
4 .05

26.36
72.82
41.16

100
100
100

lllfonn.i

Emnlovmeol
F_,al
Eu,nlnvmUII
PublicSedar
EmnlnvaSelf-emnlovment
Withoot

F.mnlnvmeot
S0.67

Formal
Fmnlnvme:nt
18.57

23.95

4.52
5.32

24.27
9.38
20.0S

23.01
6.76
21.72

Poblic

Employ..-

Self-&lt;m¡&gt;IO)'llleol

Withoul

0.63

0.36

S.92

3.23

Unanployed

Inactive Total

3.50

17.13

•-en1

22.11

100

--en1
Uaemnlnved
illadiv,
Total

Transition Matrix 2003-2004. Age 26-35
lllform.i
EmnlavmUII
Fonnal
F,.mnJnu.mmt

lnfonnal

Formal

Eu,nlnvmUIJ

Emnlnvmcot

53.81

IS.97

9.49

Self•employmenl

2.88

2.08

11.ll

2.12

1.00

3.12

16. 34

1.97

13.78

100

4.23

0.38

2.31

3.46

100

90.91
1.68

0.67
46.64

3.87
6.72

5.15

0.17
1.26
1.92
48.60

O.SI

I.IS

1.18
30.67
62.66
17.76

26.17

100
100
100
100

2L74
7.24

0.00

19.58

2.46

10.87
0 .24
1.01

19.57
84.02
32.89

100
100
100

Un&lt;mployed

Ina&lt;tive Total

7.31

80. 38

O.SI

2.19
6.30
1. 79
0.93

0.00

1.87

15.22
1.18
13.23

8. 70
0.63
14.27

4.35
0.39
4.60

6.72
12.28
3.74

19.51
4.65
11.96

Informal

1.65

Unemploy,d

0.00
0.90
0.93

lnactive

Total

13.SS

Emnlnvmcot
43.56

Formal
Emnlmnneot
12.44

Public
Sede,
0.89

4.44

17.33

Withoot
navmeot
0.44

l.33

19.56

100

Emolavmcot
Fonnal

10.47

6S.4S

2.09

2.09

3.14

0.52

1.57

14.66

100

0.00
3.45
2.13
0.00

79.41
0.00
0.21
0 .00

0.74
45.69
4.l6
3.28

5.15

0,74
0.86
3.19

Withoot

1.47
6.90
9,79
1.64

0.00
0.86
0.64
0.00

12.50
9.48
20.00
44.26

100
100
100
100

Uoanok7Ved

5.88

5.88

laactiv,

2.71
8.88

0.27
7.37

0.00
0 .09
S.00

0.00
0.90
4.ll

0.27

0.00
0.36
0. 60

70_j9
87.96

100
100
100

Inactive Total

Self--emplovmmt

1.98

10.42

........

2.26

3.85
2.56

100
100

14.27
10.24

0.94
39.89
4.62
3.61

1.21
29.26
54.03
IS.66

0.13
2.13
2.38
33.13

0 .94
1.06
1.06
0.00

31.33

100
100
100
100

25.00
6.27
16.18

26.4 7
3.43
24.91

6.62
1.71
12.35

1.47
0.12
2.63

S.88

13.11

0.00
2.01
2.08

11.76
1.71
1.87

22.79
76.35
26.86

100
100
100

8.40

2.9.1

0.58

51.38

Self-loym,ot

lllÍonnal

Un,mployed

1.60
2.64
1.20

15.43

1.57

1.35

Employ..-

Transition Matrix 2003-2004. Age 56-65

PoblicSedc,
Emnlnv.,.
Withoot
oavmenl
l.29

86.SO

2.97

Em•-...
Self-•I~ " "
W"ithool
navment
Unemnmed

loM:tive

Employ...

Inactivo
Total

Poblic

Employ..-

Self-employmeot

Emnlnvmeot

4.72
7.98
7.40
4.82

Pa.blic Sedor

Total

n.90

Pobli&lt;

Emnlnvmem
Fonnal
Emnlmnn,ot
Poblíc: Sector
Em•Self~lavment
Without
navm,ot
UnemoJOYed

Wilhoot
navm,ol
1.18

Formal
Emnlovmail
10.83

Em•,,__cot

Transition Matrices by Age Group, 2003-2004

lllfom,al

153

Revista Perspectivar Sociales I Social Perspectives primavera/spring 20()7. Vo/.9, Num. / /

2.66

13.61

Total

32.76

59.19
24.59

26.23

11.65

0.00
1.36

6.33
19.78

2.15

Sl.92

Transition Matrices by Age Groups, 1995-1996
Transition Matrix 1995-1996. Age 18-25
Emolavmem
49.84

Forn1al
Emnlovm..,
20.27

12.72

71.99

-

6.67
24.32
24.57
21.13
23.61
10.04
19.66

Transition Matrix 2003-2004. Age 36-45
lllformal

Formal
lnfonnal
Em•...... cot Emnlnvmcnt
IS. IS
51.21

Emnlmrmait

Fonnal
Emn lmnnent
l'ublicSedne

10.94

75.49

Em•""'"
Self-emolovmcat
Wilhoot

1.93
7.12
11.16
2.33

2.31
7.74
3.01
2.33

UaemnlMl'ed

u .n

loadive

4.63
12.53

11.02
1.2.l
16.66

- ..,
Total

Public

2.41

2.34

lofonnal
Employ...
1.22
1.46

Self-loym""

Withoul

14.21

. .1
0.67

3.81

0.10

90.94
1.86

o.n
51.08

26.32

1.55

l .90
0.00

7.81
4.07

60.38
17.44

1.34
44.n

3.94
1.25
17.22

3.94
0.89
5.14

L.73

0.19

15.15

0.79

7.01
15.92

2.55
2.43

Uoanployed
2.14
1.86
0 . )9
1.24
2.01
O_j8
13.39
1.25
1.63

load.ive Total
10.99
4.00
1.93
3.10
12.39
28.49
24AI
81.18
28.47

100
100
100
100
100
100
100
100
100

lofomll!I
Emnlnvmem
Formal
Em.nlnvmco.t
l'llblic Sector
Eu,n lnv"

Sclf......n1nummt
Wilhout
~ ..1
Oaanninved

Iaactive
Total

Poblíc:

Employer

Self-emplnyment

lnactivt

Total

O.SS

6.6S

Wilhout
oavm,ot
3.29

Uoanployed

2.35

3.99

13.07

100

1.99

0.44

1.69

1.10

3.38

6.69

100

6.42
S.41
9.22
7.04

70.12
S.41
4 .78
1.97

0.00
21.62
3.75
0.00

2.47
18.92
34.4 7
6.20

1.23
S.41
1.SI
30.42

3.70
2.70
3.41
2.j4

9.38
16.22
12.29
30.70

100
100
100
100

24.28

5.15

6-96

2.46

0.00
0.14

23. 04

6.50

O.SI

4.01
2.42
4.76

2.90
3.2.l
4.26

13.14
3.84
4.27

26.73
70.89
37.01

100
100
100

�154

Transition Matrices by Age Groups, 1990-1991

Transition Matrix 2003-2004. Age 26-35
lllfnnnal
Emnlovmml

laformal
Fonnal
Emnlovma,l E,gn,__,a,l
51.99
16.86

l'Dblic

Employ..- Self-anploymcnt

Unemploytd lo.active

Total

3.16

2.22

11.36

1.17

2.46

10.77

100

1.97

1.42

3.66

0.27

2.37

2.71

100

Without
-mi

Formal
Emnlovmcnt
Public Stdor
EmnlnvaSclf...-nlnvmau
W-1Joot

7.93
2.81
7.36
13.92
9.87

3.54
8.14
5.36
l.!17

87.29
1.94
2.17
1.32

0.73
46. 12
7.28
4.61

2.60
28.68
54.41
13.16

0.00
4.65
3.07
40. 13

0.63
L94
2.55
1.32

2.40
1.16
11.24
27.63

100
100
100
100

Unaanlavrd

20.62
6.26
13.60

15.98
2.99
23.10

13.40
1.25
14.84

3.09
0.38
3.73

9.79
5.50
12.53

1.03
1.80
2.24

12.37
1.41
2.13

23.71
80.41
27.82

100
100
100

- ..,
laadivt
Total

79.66

-

Transition Matrix 1990-1991. Age 18-25

Public EmployaSed«
2.62
6.12

Self-anploymmt Withoat

Un&lt;mploytd luad.iw

Total

0.58

0.00

15.16

100

húonnal

40.23

fmn.,_,,,,tlll
Formal
[mn.,_,,,,tnt
PDblicStdor
Emn'""cr
Self--nl-tnl
Withoot

10.12

64.49

5.76

4.05

8.26

0.47

0.31

6.54

100

3.38
8.37
13.16
1.79

10.71
17.24
11.40
0.00

6l.60
6.90
5.04
7.14

4.14
35.96
7.24
179

6.20
24. 14
45.39
8.93

0.19
1.97
1.10
26.79

0.56
0.49
0.66
0.00

9.21
4.93
16.01
53.57

100
100
100
100

13.64
3.84
10.03

22.73
3.92
19.81

0.00
3.59
14.15

4.55
0.49
4.92

22.73
6.78
13.74

4.55
2.94
L93

13.64
0.33
0.46

18.18
78.10
34.96

100
100
100

,_

...

Ooemnlmied

lnadiw
T'"al

-tnt
12.54

lnfonnal
fmnlnvmtnt
Formal
fmnlnvmmt
Public Sector
Em--...

Self-•---·
Withoot

10.64
1.31
4.71
10.09
4.12

74.28
1.87
5.10
3.03
2.06

2.00
87.29
2.35
1. 15
1.03

2.22
1.87
52.94
9.22
4.12

4.66

162
27.45
54.90
17.53

Unanploytd

lnactivt T ..al

0.29

2.60

12.43

100

OM

1.11

4.66

100

Withoot

0.19
1.57
1.73
45.36

0.19
1.57
1.15
0.00

4.67
4.31
18.73
25.77

100
100
100
100

22.22
84.81
36.&amp;5

100
100
100

"-mi

Ua.cm .........cd
1aadive
T'"al

22.22
3.87
9.56

5.56
0.61
11.57

1.39
0.53
13.38

4.17
0.61
6.77

27.78
6.83
18.18

U7
1..59
2.34

12.SO
1.14
1.35

Fcnnal
E,nnlovmmt

12.24

67.35

1.36

1.36

2.72

0.68

0.68

13.61

100

Pal&gt;licSednt

2.17
11,72
6.94
3.70

1.45
1.56
0.72
0.00

81.16
1.56
0.72
0.00

145
50.00
6.22
0.00

2.17
21.88
59.09
16.67

0.00
0.78
2.63
42.59

0.00
0.78
1.91
0,00

11.59
11.72
21.77
37.04

100
100
100
100

11.11
1.85
7.69

5.S6
0.48
5.56

0 .00
0.32
5.31

13.89

25.00
6.27
17.50

2.78
2.09
2.76

13.89

0.24
4.59

0.89

27.78
88.42
55.69

100
100
100

lafom,,I
FJD..L-..mt

E,nnt..,a-

Sclf-nlr,vmeot

...

Without

-

U■an--i-ec:t

laad:ive
T..al

húonnol
Fonnal
Public
E,nn....,_tnt Em......,,tnl
46.03
8.99
1.06

Employ..-

Self-tmploym,nt

_..,
W~out

Uncmploytd

laadm

T'"al

3.17

17.99

1.06

1.06

20.63

100

0.32

IDac:tivc Tola!

3.46

0.29

S.77

3.46

16 74

100

61.48

3.25

0.36

2.98

1.45

2.35

12.57

100

Emnlnvmeot
Pnblic Stdor

11.31

Ea,nlov,r

28.51

Self-nl-tn1
Witbout
~mt

18.79
11.21

16.25
19.05
20.61
1034

57.95
4.76
1 .21
0.86

0 .00
14.29
3.03
0 .00

1.77
14 29
35.15
6.90

0.35
9.52
3.64
32 76

3,18
0.00
1.82
1.72

9.19
9.52
15.76
36.21

100
100
100
100

Uoemnlnved

15.52
8.42
16.01

30.17
12.40
29.00

11.21
3.52
7.13

0.86
0.12
0.40

S.17
2.02
4.44

0.86
3.17
3.40

6.90
2.83
2.86

29.31
67.53
36.75

100
100
100

Unanploytd

lnadiw Total

Transition Matrix 1990-1991. Age 26-35
Informal
Emolovmml
Fonnal
fmn...,,,,ml

9.41

68.54

4.56

1.52

7.41

0.38

1.24

4.67
9.42
2.44

15.30
15.22
17.40
6.10

64.57
4.35
6.26
6.10

1.29
42.03
6.73
3.66

4. 19
22.46
38.52
13.41

0.32
0.72
1.16
2.3.17

0.64
1.45
1.16
1.22

9.0Z
4 .35
14.85
43.90

30.91
S.81
11.25

21.82
4.49
25.55

7.27
J.79
12.93

o.oo

9.09
4.30
10.00

0.00
2.5J
1.61

7.27

0.95
I.OS

2.3..64
77.70
34.47

Inronn,I

Fonnal

Emnlavmmt
38.00

F.mnlnvmtnt
28.00

1

.EmolD'Yer

1

Sclf-cmol-cnt 13.92

1

oavmm1

Without

l'llblic

Employe,

Self-anploymeot

Witboat

5.20

3.80

12.20

0.20

0.60

12.00

100

6.94

100

n--tlll

0.44
3.14

100
100

100
100
100
100
100

Transition Matrix 1990-1991. Age 36-45
Informal

Jnfonnal

FC111Ual

Public Employ..- Sclf-cmploymcut

Witbout

Onemploytd lnadin Total

E'mnlM,n,a¡J

EmnL-.vmmt
22.74

Sedor

6.12

2..62

12.54

n-mt
0.58

0.00

15.16

100

64.49

5.76

4.05

8.26

0.47

O.JI

6.54

100

10.71
17.24
11.40
0.00

65.60

4. 14
35.96
7.24
1.79

6.20
24.14
45.39
8.93

0.19
1.97
1.10
26.79

0.$6
G.49
0.66
0.00

9.21
4.93
16.01
53.57

100
100
100
100

4.55
0.49
4.92

22.73
6.78
13.74

4.55
2.94
1.93

0.33
0.46

18.18
78.10

100
100
100

40.23

EDJnlnvn,ml

Formal
10. 12
Emnlovma,t
Pnblic Sector
J.38
Emn.,,..,.
8.37
Self-nl-cot 13. 16
Without
1.79
navmeot
Uuemo1avcd
lnactivt
T'"al

Transition Matrix 2003-2004. Age 56-65

Unomploytd

15.55

Unao"lftVed
lnac:tive

"-mi

Self....,ploymtnl

3U2

Toeal

lllfnnnal
Formal
l'llblic Employer Self-tmploymenl
F.m ..i...-..e:ot F.m..'---mt Sector
43.93
12.43
1.45
6.07
20.81

Employer

Formal

PublicSed«

Transition Matrix 2003-2004. Age 46-55

l'llblic

Stdor

Wihoul
n-•tnl
3.61

Toeal

Fonnal
Em-'--tnl
22.74

Formal

fmnlmnntnl

Transition Matrix 2003-2004. Age 36-45
Emn....,_a,t

lofonnol
F.,mnl,wn,eot

[mn.....,nt
29.15

' laf0'1Dol

lnadÍ\--c

lafonnal

155

Revisto Perspectivas Sociales I Social Perspectives primavera/spring 2007. Yol.9, Num. I /

/ The Informal Sector in Mexico: Charocteristics and Dynamics

13.64
J.84
10.03

22.73
3.92
19.81

6.90
5.04
7.14
0.00

J.59
14. 15

13.64

34.96

�156 /

Revista Perspectivas Sociales I Social PerspecJives primaveralspring 2007. Yol.9, Num. l I Pág. I 57-175

The Informal Sector in Mexico: Characteristics ami Dynamics

Transition Matrix 1990-1991. Age 46-55
Informal
IDfonual

Formal

Em•'"""'ml Emnlnvmaat
38.S4
14.06

Public Employtr
Sedar
6.25
5.21

S&lt;lf-cmployma,t
14.58

- ..,
Wihout

Uuanployed

laad:ive Tcul

1.56

1.56

18.23

100

157

Access and Use ofHealth Care Services by Mothers and Children in the
Texas-Mexico Border Region: Preliminary Findings from the 2006 Rio
Grande Valley Health Survey

Emnlovmmt
11.32

59 75

S.66

4.09

8.18

OJl

1.89

8.81

100

5.13
5.93

12.39
14.81

9.68

9.09

Wibout

_.,,.

3.23

0.00

1.1,8
42.96
7.62
0.00

3.42
26.67
50.44
6.45

0.43
0.00
Z.05
25.81

0.85
0.00
0.29
0.00

11.11

Sclf-emolovm.ml

65.38
5.93
4.69
3.23

3.70
16.13
61.29

100
100
100
100

Uoaon.,..cd
IDaaiw
T'"al

11.11

22.22
2.48
14.50

0.00
1.76
10.10

11.11

2.58
8.53

1.14
5.48

33.33
4.03
14.09

0.00
1.24
1.44

0.00
0. 10
0.58

22.22
86.67
45.29

100
100
100

Formal

Patricia B. Reagan*
José A. Pagán**

Emnlovmcat

PublicScdor
Em•-

Transition Matrix 1990-1991. Age 56-65
lllform,1

lllform,1

Formal

Emolovmcat
35.34

f.mn~-.uall
15.52

- ...

Public Employtr
Sedar

S&lt;lf-cmployma,I Wíboul

Un... ployed

Iald.ive Tc,aJ

1.72

3.45

16.38

0.00

2.59

25.00

100

EDJn1-nnent

kmal

12.23

57.02

3.51

0.88

8.71

0.00

0.88

16.67

100

3.03
11.67
6.11
0.00

13.64
8.33
5.00
000

57.l8
1.67
1.67
0.00

1.52
36.67
7.78
0.00

3.03
21.67
51.11

1.52
1.67
1.67
23.08

0.00
0.00
0.00
0.00

19.70
18.33
26.67
46.15

100
100
100
100

0.00
2.06
6.84

25.00
1.80

0.00
0.90
4. 13

0.00
1.29
3.91

75.00

0.00
1.67
1.58

o.oo

9.09

0.00
86.12
59.80

100
100
100

Em•'"""'cat

PDblic S&lt;&lt;lo,
Em•~cr

s.lf-••-ai1
W~oul
oavmenl
UoemnlDVed

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T'"al

JO.TI

S.91
14.10

0.26
0.45

Abstract
Background: Latino/a children have the highest rate of uninsurance
among all ethnic/racial groups. There is sorne evidence that patterns
of health care use between parents and their children are interrelated.
Children are also more likely to have health insurance coverage if their
parents are insured but public insurance programs do not cover all parents of participating children. The objective of this study was to assess
whether there is a relation between patterns of health care utilization
between Latina mothers and their children who reside in the South TexasMexico border region. Survey data on 495 Latina women with children
from the 2006 Rio Grande Valley Health Survey were used to estimate
bivariate probit models of the determinants of five health care access
*Department ofEconomics, The Ohio State University 1945 N. High St. Co/umbus, OH
4322 1 Te/: 6/4-442-7385 reagan.3@osu.edu
** lnstitute far Population Health Policy and Department ofEconomics and Finance
The University ofTexas-Pan American 1201 W. University Dr. Edinburg, TX 785412999 Tel: 956-318-5306 Fax: 956-318-5303 jpagan@utpa.edu
Address correspondence to: Patricia B. Reagan, Ph.D., Professor, Department ofEconomics, The Ohio State University, 1945 N. High St., Columbus, OH 43221. Dr. Reagan
is a/so Faculty Research Associate with the Center far Human Resource Research at
OSU Dr. Pagán is a/so Director ofthe lnstitute far Population Health Po/icy al UTPA
and Adjunct Senior Fellow of the Leonard Davis lnstitute of Health Economics at the
University ofPennsylvania.
Acknowledgements: Financia/ supportfor this study was provided by the National lnstitute of Child Health and Human Development through a seed grant from the lnitiative in Population Research al The Ohio State University. We thank Margare/ Plahuta
and José E. Olivares f ar their excellent assistance in survey development. We also thank
the participants of the 2006 Human Copita/ Symposium al the Universidad Autónoma
de Nuevo León in Monterrey, México far their helpful comments and suggestions.
ISSN 1405-1133 C 2007 Universidad Autónoma de Nuevo León, University ofTexas ofAustin,
University ofTexas of Arlington, University ofTennessee,
Universidad Juárez del Estado de Durango, Universidad de Colima.

�158 /

Access ami Use ofHealth Care Services by Mothers ami Children in the Texas-Mexico Border
Region: Preliminory Findings from the 2006 Rio Grande Va/ley Health Survey

and utilization indicators. Pattems of health care utilization between
Latina mothers and their children were positively related for having
a usual place of care, visiting a doctor, visiting an emergency room,
and having delayed health care needed. Both desirable and undesirable
parental and child health care access/utilization pattems for Latinos/as
are interrelated. Interventions that promote good healtb care utilization
behavior for Latina mothers seem to spillover to their children. Public
health insurance programs that focus on covering uninsured children
but leave tbeir parents uninsured may end up not taking full advantage
of the positive spillover effects of health care access/utilization from
mothers to their children.

KeyWords
Uninsured; Latino/a; Hispanic; Children; Health Care

Resumen
Los niños latinos tienen la más alta tasa de no aseguramiento médico
entre todos los grupos raciales. Hay evidencia de la interrelación padres
- hijos en los patrones de cuidados de la salud. Los niños tienen mayor
probabilidad de estar cubiertos si sus padres lo están pero los programas
públicos de seguridad no cubren a todos los padres de los niños participantes. El objetivo de este estudio fue evaluar la interrelación entre los
patrones de utilización de cuidados de la salud entre madres latinas y
sus hijos para residentes en la región de Texas fronteriza con México.
Se utiliza la Encuesta de Salud del Valle de Río Grande 2006 con datos
muestrales de 495 mujeres latinas con hijos y se estiman modelos Probit
para cinco indicadores de acceso a los cuidados de salud. Los patrones
de la utilización de los cuidados de la salud para madres latinas y sus
hijos estuvieron positivamente relacionados para los indicadores de:
lugar habitual de cuidado de la salud, visita al médico, visita a salas de
emergencia y posposición en los cuidados. Los patrones de utilización
de los cuidados de salud entre padres e hijos están interrelacionados
tanto en formas deseadas como no deseadas. Las intervenciones que
promueven una conducta de utilización de cuidados de la salud para
madres latinas parecen extenderse a sus hijos por lo que los programas
públicos de salud que se enfocan en los niños no cubiertos dejando de
lado a los padres pierden este beneficio.

Revista Perspectivas Sociales I Social Penpectives primavera/spring 2007. VoL9, Num. 1 I

159

Palabras clave
Asegurados, Latino/a, Hispánico, Niños, Cuidados de la salud.

Introduction
Many communities in the U.S.-Mexico border region are characterized
by high poverty rates and, not surprisingly, high uninsurance rates and
low access to health care (Bastida, Brown and Pagán, 2007). About one
of every four children and adults in Texas do not have health insurance
coverage--the highest proportion in the U.S.- and access disparities are
even higher in counties bordering Mexico. Slightly over one of every
three children and adults in the Rio Grande Valley- which includes
Cameron, Hidalgo, Starr and Willacy counties- are uninsured (U.S.
Census Bureau, 2005).
Lack of health insurance coverage has important negative consequences in terms of access to health care and health outcomes not
only for individuals but also for entire families (Institute of Medicine,
2002; Institute ofMedicine, 2004). A recent report from the Institute of
Medicine (Health Insurance is a Family Matter) concluded that children are more likely to have health insurance coverage if their parents
are insured (lnstitute of Medicine, 2002). Many uninsured children are
eligible for public programs such as Medicaid and the State Children's
Health Insurance Program (SCHIP), yet, many uninsured children remain
without health insurance coverage and there are severa} reasons for this.
For example, many children become ineligible for sorne public health
programs after a certain age and, thus, become uninsured as they get
older. Employer-sponsored health insurance coverage is also important
because the linkage between employrnent and health insurance coverage increases the chances that children become uninsured when parents
transition from employment to unemployment, and vice versa.
Recent research also has sbown that pattems of health care use
between parents and their children are interrelated (Mink:ovitz et al.,
2002). Parental age, ethnicity, race, education, socioeconomic status and
the family unit structure are ali connected to a child's use ofhealth care
services (Newacheck et al., 1998; Weinick, Weigers and Cohen, 1998).
There is also sorne evidence that the self-reported health status of moth-

�160 /

Access and Use ofHealth Care Services by Mothers and Children in the Texos-Mexico Border
Region: Preliminary Findings from the 2006 Rio Grande Va/ley Hea/th Survey

ers and their children are correlated (Minkovitz et al., 2002). What is not
known is whether sorne ofthese results extend to low income mothers and
children, particularly ofLatino descent. Hispanics have the highest rate
of uninsurance in the U.S. and a better understanding of the patterns of
health care access and use between parents and children is an important
health policy concern if we are interested in substantially reducing health
disparities.
In this study, we report preliminary results from the 2006 Rio
Grande Valley Health Survey (RGVHS), a telephone survey of 908
women between the ages of 19 and 55 residing in Cameron, Hidalgo,
Starr and Willacy counties. More specifically, we collected extensive
socioeconomic, demographic, health status and health care utilization
data on mothers and one randomly-selected child from each household.
Toe preliminary results reported here pertain to 495 mother-child pairs
for which we had complete data.
Toe main objective of our study is to assess whether there is a
relationship between patterns of health care utilization between borderdwelling Latina mothers and their children. This is an important policyrelevant issue because if good (and/or bad) health care utilization patterns
of parents spillover to their children then it may malee sense to facilitate
health insurance coverage to all parents regardless ofthe health insurance
status of their children. Current SCHIP policy in Texas provides health
coverage to some-but not all-parents of insured children participating
in this public health insurance program (Task Force on Access to Health
Care in Texas, 2006).

Methods
Data Description
Toe 2006 Rio Grande Valley Health Survey includes socioeconomic,
demographic, health status and health utilization data from 908 women
between the ages of 19 and 55 that reside in Cameron, Hidalgo, Starr
and Willacy counties in South Texas. Toe sample is representative of the
estimated 290,811 women that resided in the RGV in 2006. Communities along this U.S.-Mexico border region have among the highestrates
of poverty and uninsurance in the U.S. Toe most recent U.S. Census

Revista Perspectivas Sociales I Social Perspeclives primavera/spring 2007. Vol.9. Num. / /

161

estimates show that 323,852 people (32.4 percent) were uninsured in the
four-county RGV area in 2000, 120,269 of them were children. About
32 percent ofchildren/adults (34 percent of children) in this region were
uninsured in 2000 (U.S. Census Bureau, 2005). Thirty-one percent of
the population in this region lived below the poverty line in 2003 (42.5
percent of children ages 0-17) (U.S. Census Bureau, 2006).
Telephone interviews were conducted in English or Spanish depending on the preference ofthe respondent from January to September 2006.
The survey included sections with questions on demographics, immigration, health status, employment, health insurance, healtb care utilization
and participation in social programs. Mothers also answered questions
in these seven areas about one randomly-selected child between the ages
of one to 13 years of age residing in the same household.
Sampling weight adjustments were developed to account for households without a telephone and households with multiple residential
telephone lines. Post-strati:fication adjustments were also conducted
based on age, county of residence, education and income. The weighted
sample is representative ofwomen 19-55 residing in the four RGV counties (290,811 in 2006, based on our own projections from the 2000 U.S.
Census and the 2004 American Community Survey).

Dependent Variables
We constructed five mother-child pairs of dichotomous dependent variables based on the mothers' answers to the following questions: (1) "Is
there a place that you usually go to when you are sick or need advice
about your health?" and "Is there a place where you usually take him/her
when he/she is sick or you need advice about his/her health?; (2) "During
the past 12 months, how many times have you seen a medica! doctor
about your own health? and "During the past 12 months, how many times
has he/she seen any kind of medical doctor?"; (3) "During the past 12
months, did you visita hospital emergency room for your own health?"
and "During the past 12 months, did he/she visit a hospital emergency
room?"; (4) "During the past 12 months, did you visita dentist?" and
"During the past 12 months, did he/she visita dentist?; and (5) "During
the past 12 months, did you delay getting any other medica! care you

�162 /

Access and Use o/Health Care Services by Mothers and Children in the Texas-Mexico Border
Region: Pre/imina,y Findings .from the 2006 Ria Grande Va/ley Health Survey

felt you needed, such as seeing a doctor, a specialist or other health professional?" and "During the past 12 months, did you delay getting any
other medical care for your son/daughter you felt he/she needed, such as
seeing a doctor, a specialist or other health professional?". Toe motherchild questions on (2) above about the number ofvisits to a doctor were
coded as one for one or more visits, and zero otherwise.
We hypothesize that health care access/utilization patterns across
these five dimensions--usual place ofcare, visiting the doctor, emergency
room or dentist, and delaying medical care needed- are positively related
between mother-child pairs, even after controlling for other factors that
may be related to health care access/utilization.

Revista Perspectivas Sociales / Social Perspeclives primavera/spring 2()()7. Vol.9, Num. I /

163

health care access/utilization varied for child-mother pairs across the
independent variables included above (Greene, 2003). We used a bivariate probit specification because we are interested in evaluating the sign
and statistical significance of the correlation coefficient of the residuals
from the two jointly-estimated probit models. This coefficient tells us
whether the health care access/utilization pattems of mothers and children are related even after controlling for all the factors posited to be
related to access/utilization (i.e., perceived need for health care services,
individual predisposing characteristics and factors that enable access to
and utilization ofhealth care services). The bivariate probit models were
estimated using Stata 9.2 (StataCorp, 2005).

ResuJts

Independent Variables

........

Toe determinants of health care access/utilization in a U.S.-Mexico
border context for both mothers and children were selected based on
the precept that access/utilization varies with the perceived need for
health care services, individual predisposing characteristics and factors
that enable access to and utilization of health care services (Andersen
and Davidson, 2001; Andersen et al., 2002). Toe independent variables
explaining the health care access/utilization patterns of children were
years of age, gender, self-reported health status (fair/poor vs. good/very
good/excellent), yearly household income (less than $10,000, between
$10,000 and $30,000, between $30,000 and $50,000, and more than
$50,000) and health insurance status (insured vs. uninsured). For mothers,
the independent variables explaining health care access/utilization patterns were years of age, marital status (married vs. otherwise), immigrant
status (immigrant vs. otherwise), self-reported health status (fair/poor
vs. good/very good/excellent), education (less than high schooJ, high
school and sorne college, and college graduate), yearly household income
(less than$10,000, between $10,000 and $30,000, between $30,000 and
$50,000, and more than $50,000) and health insurance status (insured
vs. uninsured).
Statistical Model
We estimated five bivariate probit regression models to analyze bow

Table 1 presents the weighted means and standard errors for all the childmother variables. Ninety-six percent ofchildren had a usual place where
they obtained health care services but only 81.40 percent ofmothers had
a usual place for medical care. Ninety-three percent of children had at
least one visit to a doctor in the last 12 months befare the interview but
only 80.44 percent of mothers had visited a doctor during the same time
period. Only 12.00 percent of children had visited an emergency room in
the last year compared to 16.08 percent ofmothers. Seventy-four percent
of children had visited a dentist within the previous year compared to
only 34.77 percent of mothers. Only 4.00 percent of children report to
have had any delays in health care within the past year compared to 7.60
percent of mothers.

�164

I Access ami Use ofHealth Care Services by Mothers and Chüdren in the Texas-Mexico Border
Region: Preliminary Fimlings.from the 2006 Rio Grande Va/ley Health Survey

TABLE 1: Sample Means
1 Mean
Child-Usual Place Care 1 .9636
Motber-Usual Place Care 1 .8140
Child-Doctor Visit 1 .9340
Mother-Doctor Visit 1 .8044
Child-ER Visit I .1200
Mother-ER Visit 1 .1608
Child-Dentist Visit 1 .7371
Mother-Dentist Visit 1 .3477
Child-Delayed Care I .0400
Motber-Delayed Care .0760
Child-Age 5.2338
Mother-Age 33.2197
Child-Female .4570
Motber-Immigrant .7265
Child-Fair/Poor Health .1058
Mother-Fair/Poor Health .2769
Child-Insured .7943
Motber-Insured .2881
Married .6908
Less than HS .5433
HS &amp; Sorne College .3552
College Graduate .1015
HH Income &lt;$1 0K .4490
HH Income $10K-$30K .3945
HH Income $30K-$50K .0872
HH Income &gt;$50K .0692

SE
.0103
.0230
.0134
.0227
.0196
.0221
.0251
.0267
.0124
.0159
.1990
.4777
.0285
.0247
.0177
.0254
.0225
.0251
.0274
.0281
.0266
.0148
.0288
.0275
.0148
.0133

[95%
.9433
.7688
.9076
.7597
.0834
.1174
.6878
.2952
.0157
.0446
4.8425
32.2801
.4010
.6778
.0710
.2270
.7501
.2387
.6370
.4880
.3028
.0725
.3925
.3404
.0580
.0430

CI]
.9839
.8593
.9605
.8491
.1565
.2042
.7865
.4003
.0643
.1074
5.6251
34.1591
.5131
.7751
.1406
.3269
.8387
.3376
.7447
.5986
.4075
.1306
.5056
.4487
.1163
.0955

Toe mean age of children and tbeir mothers was 5 .23 years and
33 .22 years, respectively. Almost three quarters of the mothers surveyed
(72.65%) were immigrants. About l 0.58 percent of the mothers reported
that their children were in fair or poor health whereas 27.69 percent of
mothers reported their own health to be fair/poor. Almost four-fifths of
children (79.43 percent) were covered by any type of health insurance
coverage compared to only 28.81 percent of mothers. This health insurance coverage rates are relatively low compared to what is typically
reported for tbe U.S.-Mexico border region. Toe 2006 RGVHS only
includes women between the ages of 19 and 55 and, consequently, the

Revista Perspectivas SocitJ/es / Social Perspectives primavera/spring 2007. Vo/.9, Num. 1 I

165

health insurance coverage rates are likely to be mucb lower for this
relatively younger population than for the overall population. Sixty-nine
percent of women in the sample were married at the time of the interview. More tban half of the mothers (54.33 percent) bad less tban a high
school education, 35.52 percent hada high school education or sorne
college, and 10.15 percent were college graduates. Almost 45 percent
hada household income of less than $10,000 per year, 39.45 percent
hada household income between $10,000 and $30,000 per year, 8.72
percent earned between $30,000 and $50,000, and only 6.92 percent had
a household income of more than $50,000 .
Tables 2 to 6 report the coefficients for the five bivariate probit
models of child-mother health care access/utilization. Before proceeding
with the main results based on the correlation coefficient of the estimated
residuals, it is worth noting a few of tbe statistically significant determinants of healtb care access/utilization for both mothers and children.
Table 2 shows that girls were less likely to have a usual place of bealtb
care than boys in our sample. Also, insured children were more likely
to have a usual source of care. Children residing in households with
income levels greater tban $50,000 had a higher probability of having
a usual place for obtaining healtb care tban those earning less. Insured
mothers were more lik.ely to bave a usual source of care tban uninsured
mothers.

�166 / Access and Use ofHealth Care Services by Mothers ami Children in the Texas-Mexíco Border

Revista Perspectivas Sociales / Socíal Perspeclíves primaveralspring 2007. Vol. 9, Num. / /

Region: Prelímínary Findíngs from the 2006 Río Grande Va/ley Health Survey

TABLE 2: Bivariate Probit Model for Having a Usual Place of Care
SE

Coef.
Child has Usual Place of Care
0.004
Age
-0.370*
Female
-0.194
Fair or poor health
0.016
HH lncome $10K-$30K
0.273
HH lncome $30K-$50K
5.751 ***
HH lncome &gt;$50K
1.021 ***
Insured
1.051***
Constant
Mother has Usual Place of Care
0.010
Age
0.199
Married
0.179
I.mmigrant
0.008
Fair or Poor Health
-0.100
HS &amp; Sorne College
0.153
College Graduate
0.169
HH lncorne $10K-$30K
0.003
HH Incorne $30K-$50K
0.065
HH Incorne &gt;$50K
0.560***
lnsured
-0.114
Constant
0.569***
Rho

\
\
1

Chi2
Observations

(0.026)
(0.199)
(0.278)
(0.196)
(0.328)
(0.244)
(0.179)
(0.245)
(0.009)
(0.150)
(0.165)
(0.153)
(0.145)
(0.237)
(0.147)
(0.281)
(0.333)
(0.187)
(0.385)
(0.144)
15.602

495

Standard errors in parentheses
* p&lt;0.10, ** p&lt;0.05, *** p&lt;0.01

TABLE 3: Bivariate Probit Model for Having Visited a Doctor
Coef.
Child-Doctor Visit
Age
- 0.029
Female
0.341 *
Fair or Poor Health
0.101
lilI Income $1 OK-$30K -0.054
lilI Income $30K-$50K
0.060
lilI Income &gt;$50K
-0.106
Insured
1.017***
Constant
0.770***
Mother-Doctor Visit
Age
0.002
Married
0.205
lmmigrant
-0.017
Fair or Poor Health
-0.016
HS &amp; Sorne College
-0.154
College Graduate
- 0.053
lilI Income $10K-$30K
0.023
lilI Income $30K-$50K -0.412
lilI Income &gt;$50K
-0.005
Insured
0.552***
Constant
0.350
Rho
0.236*
Chi2
Observations

3.525
465

Standard errors in parentheses
* p&lt;0.10, ** p&lt;0.05, *** p&lt;0.01

SE
(0.025)
(0.194)
(0.254)
(0.202)
(0.328)
(0.345)
(0.189)
(0.250)
(0.010)
(0.154)
(0.169)
(0.154)
(0.149)
(0.226)
(0.151)
(0.259)
(0.321)
(0.178)
(0.383)
(0.126)

167

�168

\

/ Access and Use ofHealth Care Services by Mothers and Children in the Texas-Mexico Border
Region: Pre/iminary Findings from the 2006 Rio Grande Va/ley Health Survey

TABLE 4: Bivariate Probit Model for Having an Emergency Room
Visit
SE
Coef.
Cbild-ER Visit
(0.024)
-0.051**
Age
(0.162)
Female
0.035
(0.224)
Fair or Poor Health
0.366
HH lncome $1 OK-$30K -0.236
(0.181)
HH Income $30K-$50K
0.306
(0.279)
(0.283)
0.272
HH lncome &gt;$50K
(0.202)
Insured
0.197
(0.243)
-1.161***
Constant
Mother-ER Visit
(0.012)
Age
- 0.016
Married
0.038
(0.186)
(0.213)
Immigrant
0.016
0.558***
(0.184)
Fair or Poor Health
(0.183)
HS &amp; Sorne College
0.105
(0.273)
College Graduate
- 0.222
(0.184)
HH Income $10K-$30K - 0.429**
HH Income $30K-$50K - 0.693*
(0.375)
HH Income &gt;$50K
- 0.316
(0.363)
lnsured
0.336
(0.209)
Constant
- 0.674
(0.440)
Rho
0.218*
(0.121)
Chi2
Observations

3.241
489

Standard errors in parentheses
* p&lt;0.1 O, ** p&lt;0 .05, *** p&lt;0.01

Revisto Perspectivos Sociales / Socio/ Perspectives primavera/spring 2007. Vol9, Num. J /

TABLE 5: Bivariate Probit Model for Having Visited a Dentist
Coef.
Child-Dentist Visit
Age
Female
Fair or Poor Health
HH Income $10K-$30K
HH Income $30K-$50K
HH Income &gt; $50K
Insured
Constant
Mother-Dentist Visit
Age
Married
Immigrant
Fair or Poor Health
HS &amp; Sorne College
College Graduate
HH Income $10K-$30K
HH Income $30K-$50K
HH Income &gt;$50K
Insured
Constant
Rho

chi2 e
Observations

SE

0.038**
-0.060
-0.234
0.007
-0.133
0.256
0.714***
-0.134

(0.019)
(0.134)
(0.201)
(0.145)
(0.235)
(0.294)
(0.153)
(0.204)

0.017*
0 .281*
-0.057
-0.301**
0.173
0.326
0.416***
0.211
0 .815***
0.582***
-1.698***
0.069

(0.009)
(0.152)
(0.158)
(0.148)
(0.147)
(0.213)
(0. 148)
(0.242)
(0.287)
(0.158)
(0.359)
(0.092)

0.569
488

Standard errors in parentheses
* p&lt;0.10, ** p&lt;0 .05, *** p&lt;0.01

169

�170 / Access and Use of Health Care Services by Mothers and Children in the Texas-Mexico Border
Region: Preliminary Findings from the 2006 Río Grande Va/ley Health Survey

TABLE 6: Bivariate Probit Model for Having Delayed Care
Coef.
Child-Delayed Care
Age
Female
Fair or Poor Health
HH Income $10K-$30K
HH Income $30K-$50K
HH Income &gt;$50K
Insured
Constant
Mother-Delayed Care
Age
Married
Immigrant
Fair or Poor Health
HS &amp; Sorne College
College Graduate
HH Income $10K-$30K
HH Income $30K-$50K
HH Income &gt;$50K
lnsured
Constant
Rho

~
"-.__
'

\1

Chi2
Observations

SE

0.000
-0.733**
0.366
-0.932**
-0.631
-0.561
-0.656**
-0.782**

(0.032)
(0.330)
(0.367)
(0.419)
(0.441)
(0.461)
(0.290)
(0.347)

0.002
0.059
-0.006
-0.093
- 0.119
-5.773***
0.088
-0.256
0.585
-0.040
-1.509***
0.424*

(0.014)
(0.269)
(0.251)
(0.251)
(0.225)
(0.511)
(0.248)
(0.520)
(0.528)
(0.296)
(0.500)
(0.217)

3.825
388

Standard errors in parentheses
* p&lt;0.10, ** p&lt;0.05, *** p&lt;0.01

Revista Perspecüvas Socio/es I Social Perspeclives primavera/spring 2007. Vo/.9, Num. l l

171

Table 3 reports the results for having visited a doctor at least once
within the previous year. Girls were more likely to have visited a doctor
than boys. Health insurance was a statistically significant determinant
of doctor visits for both children and their mothers. Table 4 reports the
results for visiting an emergency room within the previous year. Toe
child's years of age was negatively related to having visited an emergency room. Mothers in fair/poor health were more likely to have visited
an emergency room than those in good, very good or excellent health.
Household income was negatively related to visiting an emergency room
within the last year.
Table 5 shows that, for both the child and the mother, years of age
were positively related to having visited a dentist within the Iast year.
Insured children and mothers hada higher propensity ofhaving visited
a dentist than uninsured children and mothers. Married mothers were
more likely to have visited a dentist than non-married mothers. Mothers
in fair/poor health were less likely to have visited a dentist than those in
good, very good or excellent health. Household income was positively
related to having visited a dentist.
Table 6 shows the results for whether the child or the mother delayed
needed health care within the last year. Girls were less likely to have delayed care than boys. Children with household income between $10,000
and $30,000 were less likely to report that they had delayed care than ali
others. Insured children were less li.kely to have delayed needed health
care than uninsured children. Mothers with a college degree were less
likely to report that they had delayed care than those that did not have a
college degree.
Tables 2-6 also report the correlation coefficient for the residuals
of the bivariate probit models. The residual correlation coefficients
between the child and the mother probit equations were positive and
statistically significant for having a usual place of care, visiting a doctor,
visiting an emergency room, and having delayed health care needed. The
coefficient was positive but statistically insignificant for having visited
a dentist.

�172 / Access ami Use ofHealth Ca1tl Services by Mothers anti Children in the Texas-Mexico Border

Revista Perspectivas Socio/es I Socio/ Perspectives primavera/spring 2007. Yol.9. Num. J /

173

Region: Preliminary Findings from the 2006 Río Grant/e Ya/ley Health Survey

Discussion
Using survey data from the 2006 RGVHS we found that the residual
correlation coe:fficients of child and mother bivariate probit equations
of four health care access/utilization indicators were highly correlated.
Regression-adjusted pattems of health care utilization between Latina
mothers and their children were positively related for having a usual
place of care, visiting a doctor, visiting an emergency room, and having
delayed health care needed. Toe child-mother patterns were not statistically significant for having visited a dentist.
The results presented above are consistent with the premise that both
desirable and undesirable parental and child health care access/utilization
pattems for Latinos/as are interrelated. That is, good health care utilization behavior from Latina mothers-such as having a usual source ofcare
and visiting a doctor-are strongly related to the health care utilization
behavior of their children. However, poor health care utilization and access pattems for Latina mothers- in the form of visits to the emergency
room and delaying needed medica} care-are also strongly related to the
health care utilization and access patterns of their children.
Toe results presented here have important health policy implications
because they suggest that interventions that promote good health care
utilization behavior for Latina mothers spillover to their children. Thus,
for example, public health insurance programs that focus on covering
uninsured children but leave their parents uninsured may end up not
taking full advantage of the positive spillover effects of health care access/utilization from mothers to their children.
SCIIlP was created as part ofthe Balanced Budget Act of 1997 with
the goal of providing health insurance coverage to uninsured children of
families who did not qualify for Medicaid and at the same time could not
to purchase prívate health insurance coverage. The federal goverrunent
pays for almost three-fourths of the Texas SCHJP and, still, Texas has
retumed money to the federal government every year since SCHIP began
that could have been used to expand coverage to more families (Task
Force on Access to Health Care in Texas, 2006). Toe results presented
above provide further support to the idea that relaxing the eligibility

rules for uninsured parents of children covered by public health insurance programs may make sense if we want to promote a better use of
the health care system by Latina mothers and their children.

�174 /

Access and Use o/ Health Care Services by Mothers a,ul Children in the Texas-Mexico Border
Region: Pre/iminary Findingsfrom the 2006 Río Grande Va/ley Health Survey

References

Andersen, R. and P. Davidson. (2001 ). lmproving access to care in
America: Individual and contextual indicators. Cbanging the US. health
care system: Key issues in health services, policy and management. R.
R. Anderson, T. and G. Kominski. San Francisco, Jossey-Bass.
Andersen, R. M., H. Yu, R. Wyn, P. L. Davidson, E. R. Brown and S.
Teleki. (2002). "Access to medical care for low-income persons: how do
communities make a difference?" Med Care Res Rev 59(4): 384-411.
Bastida, E., H. S. Brown and J. A. Pagán. (2007). Health insurance
coverage and health care utilization along the U.S._Mexico border:
evidence from the Border Epidemiologic Study of Aging. The Health
of Aging Hispanics: The Mexican-Origin Population. J. L. Angel and
K. E. Whitfield. New York, NY, Springer.
Greene, W. H. (2003). Econometric Analysis. Upper Saddle River, NJ,
Prentice Hall.
Institute ofMedicine. (2002). Care without coverage: Too little, too late.
Washington, DC, National Academies Press.
Institute of Medicine. (2002). Health Jnsurance is a Family Matter.
Washington, DC, National Academies Press.
Institute ofMedicine. (2004). lnsuring America shealth: Principies and
recommendations. Washington, DC, National Academies Press.
Minkovitz, C. S.; P. J. O'Campo; Y. H. Chen and H. A. Grason. (2002).
"Associations between maternal and child health status and patterns of
medical care use." Ambul Pediatr 2(2): 85-92.
Newacheck, P. W.; J. J. Stoddard; D. C. Hughes and M. Pearl. (1998).
"Health insurance and access to primary care for children." N Engl J
Med 338(8): 513-9.
StataCorp. (2005). Base Reference Manual. College Station, TX, Stata
Press.

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175

Task Force on Access to Health Care in Texas. (2006). Code Red: The
Critica/ Condition ofHea/th In Texas. Austin, TX, University of Texas
System.
U.S. Census Bureau. (2005). Small Area Health Insurance Estimates.
U.S. Census Bureau. (2006). Small Area Income &amp; Poverty Estimates.
Weinick, R. M .; M. E. Weigers and J. W. Coben. (1998). "Children's
health insurance, access tocare, and health status: new findings." Health
Aff{Millwood) 17(2): 127-36.

�Revista Perspectivas Sociales I Social Perspectives primavera/spring 2007. Vo/.9, Num. 11 Pág. 177-196

177

Diabetes and Employment Productivity:
Does Diabetes Management Matter?
H. Shelton Brown, ID t, José A Pagántt,
Craig Hanis, t Adriana Pérez¡t*

Abstract
Diabetes has been shown to have a detrimental impact on employment
and labor market productivity, which results in lost work days and higher
mortality/disability.
This study utilizes data from an ongoing diabetes-related survey of
households in Brownsville, Texas, a largely Mexican American metropolitan area on the Texas-Mexico Border, in order to assess the impact
of diabetes on work productivity. We focus on two questions. First,
does the management of diabetes increase productivity in the short run?
Diabetes management is measured by the interaction of having diabetes
and glycosylated hemoglobin levels (Hbalc). Second, are women with
diabetes less productive at higher levels of earnings? Methods used
include ordinary least squares (OLS), quantile regression and Heckman
regression. Concerning the first question, the management of diabetes

\

\
1

f University ofTexas Hea/th Science Center at Houston School ofPublic Health Division of Management, Policy, ami Community Health Schoo/ of Public Health Building Brownsville, Texas 78520 Tel. 956-882-5164; Fax 956-882-5152 E-mail: henry.
s.brown@uth.tmc.edu
ff University o/Texas-Pan American 1201 W University Drive Edinburg, Texas 78541
Tel. 956-318-5306; Fax 956-318-5303 E-mai/:jpagan@utpa.edu
t University ofTexas Hea/th Science Center at Houston School ofPublic Hea/th Division of Epidemiology 1200 Herman Pressler Dr., RAS E401 Houston, Texas 77030
Tel. 713-500-9807 E-mail: Craig.L.Hanis@uth.tmc.edu
11 University ofTexas Health Science Center at Houston Schoo/ ofPublic Health Division ofBiostatistics School ofPub/ic Hea/th Building Brownsville. Texas 78520
Tel. 956-882-5160; Fax 956-882-5152 E-mail: adriana.m.perez@uth.tmc.edu
•Financia/ supportfor this $·tudy was provided by the Hispanic Health Research Center
at the Brownsville Regional Campus ofthe University o/Texas School ofPub/ic Health
(N[H CMHD P20 MD000170-04).
ISSN 1405-1133 O 2007 Universidad Autónoma de Nuevo León, University ofTexas ofAustin,
University ofTexas of Arlington, University ofTennessee,
Universidad Juárez del Estado de Durango, Universidad de Colima

�178 / Diabetes anti Employment Productivity: Daes Diabetes Managemen/ Matter?

Revista Penpectivas Sacia/es / Sacia/ Perspeclives primavera/spring 2007. Vo/.9, Num. 1/

does not appear to have a discernible impact on labor market outcomes
in the short-run. However, diabetes does negatively affect both male and
female productivity. Women with diabetes are less productive at higher
wage levels.

portant part of these costs are labor productivity losses (Bastida &amp;
Pagán 2002, Brown m, Pagán &amp; Bastida 2005, Kahn 1998, Ng, Jacobs
&amp; Johnson 2001 , Lavigne, Phelps, Mushlin &amp; Lednar 2003). Further,
the US Census Bureau estimates that from 2002 to 2020 the number of
individuals diagnosed with diabetes will increase by 44 percent to 17.4
million (American DiabetesAssociation 2003). With the prevalence and
incidence of diabetes increasing, accurate estimates of the labor market
cost of diabetes are important in order to develop appropriate health
policy responses.

Keywords
Quantile Regression, Heckman Model, Hbalc, Labor.

Resumen
Se ha demostrado que la diabetes tiene un impacto negativo en el empleo
y en la productividad del mercado de trabajo, resultando en días perdidos
de trabajo, en mayores días de incapacidad y mayor mortalidad. Este
estudio utiliza información de una muestra de hogares relacionada a la
diabetes que está en progreso en Brownsville, Texas, la cual es un área
metropolitana en gran parte México-Americana en la frontera de Texas
con México, y que busca evaluar el impacto de la diabetes en la productividad del trabajo. Nos enfocamos en dos preguntas. Primero, ¿el
manejo de la diabetes incrementa la productividad en el corto plazo? El
manejo de la diabetes se mide como la interacción entre tener diabetes
y los niveles de hemoglobinaglicosilada (Hbalc).
Segundo, ¿son menos productivas las mujeres con diabetes a altos
niveles de ingresos laborales? Los métodos utilizados incluyen Mínimos
Cuadrados Ordinarios (MCO), regresiones cuantílicas y la regresión de
Heckman. En relación a la primera pregunta, el manejo de la diabetes no
parece tener un impacto discernible en el corto plazo sobre los resultados
en el mercado de trabajo. Sin embargo, la diabetes afecta negativamente
la productividad tanto de la mujer como del hombre. Las mujeres con
diabetes son menos productivas a niveles salariales más altos.

Palabras clave
Regresión cuantilica, Modelo de Heckman, Hbalc, Trabajo.
Introduction
Diabetes is a disease wbich has economic implications. Toe American
Diabetes Association estimates that diabetes costs the U.S. econoJDY
$132 billion per year (American Diabetes Association 2003). An iJD-

179

Given the high economic costs of diabetes (American Diabetes Association 2003), public health officials have been arguing that diabetes
prevention is important. Prevention could mean one oftwo things: Toe
prevention of the onset of diabetes, or the prevention of diabetes-related
problems through the management of glycosylated hemoglobin levels
(Hbalc) for people already diagnosed with diabetes. If the productivity
costs of diabetes when diabetes is managed are low, scarce prevention
dollars could be concentrated on the much smaller subpopulation already
diagnosed with diabetes. On the other hand, if the costs associated with
diabetes are substantial, whether managed or not, then prevention dollars must be spread over the much larger general population. Of course
. .
'
1t ts likely that dollars should be spent on both preventing the onset of
diabetes as well as its management after onset. However, there is currently no information to inform policy-makers on how to apportion scarce
prevention dollars between diabetes onset and diabetes management.
Toe labor market component of the overall cost of diabetes is important. However, while overall diabetes-related costs are rising, it is not
clear that per capita labor costs associated with diabetes are increasing.
!echnological changes over the last three decades have led to changes
m the labor market and in the medical field. First, there are increases
in the number ofjobs that are less physically demanding and therefore
accessible to persons with diabetes (Kahn 1998). Second, new drugs,
glycosylated hemoglobin levels (Hbalc) monitoring devices and food
science advances, such as artificial sweeteners, are also making diabetes
,,
" .
management eas1er and less costly than before.
Brown, Pagán and Bastida show that the effects ofdiabetes on work

�180 /

Diabetes and Emp/oyment Produclivily: Does Diabetes Management Matter?

propensity are more important for men than for women (Brown m et
al. 2005). Anecdotally, many believe tbat women are more inclined to
manage their diabetes through pbysician visits, diligent use of pharmaceuticals, use of monitoring devices and health behavior modification.
This would explain why they have less diabetes-related labor market
problems in comparison to roen. With the laboratory-measured Hba1e
data in our study, we can test this hypothesis.
This study adds two important elements to the growing literature
on diabetes and labor market outcomes. First, we examine whether poor
diabetes management is the cause of adverse labor market outcomes
rather than diabetes per se. In our data, Hbalc levels are measured in a
laboratory for all participants, whether or not they have been diagnosed
with diabetes by a physician. Thus, we know the extent to whicb persons
with diabetes have managed their Hbalc. Second, we examine whether
diabetes affects labor productivity, whether managed or not, across wage
levels using quantile regression.

......

\
\

We used microdata from tbe Diabetes Impact Project, an ongoing
survey from a predominantly Mexican American area of South Texas.
Our data has important advantages. Toe Diabetes lmpact Pro ject surveys
Mexican Americans, a population which has a high prevalence and incidence of diabetes. Toe percentage of this population diagnosed with
this health condition is expected to rise from 1.4 million in 2002 to 2.9
miIlion in 2020, a l 07 percent increase (American Diabetes Association
2003). By contrast, the total US population diagnosed with diabetes is
expected to increase by 44 percent during the same time period. Our data
also has laboratory-measured Hbalc levels, necessary for the assessing
the level ofblood sugar management for persons with diabetes.

Diabetes Self-Management and Health Capital
One of our main bypotheses is that unmanaged diabetes is correlated
with labor productivity. Michael Grossman argued that "healtb capital"
is a measure ofhealth stock, reflective ofpast health behavior (Grossman
1972). If a personjogs or changes their diet, for instance, their health
stock does not instantly change. However, jogging and dietary changes
maintained over a long period increase his/her bealth stock. Further, if

Revista Perspectivas Sociales I Social Perspeclives primavera/spring 2007. Yo/. 9, Num. ¡ ¡

181

a person tempo~arily stops jogging or occasionally eats unhealthy food
after a long penod of adberence, his/her health stock will not be greatly
affe~ted. ?f c~urse, the Grossman model maintains that healthy behavior
reqwres time mputs (Grossman 1972).
He~oglobin is a protein which is found in red blood cells. Like a
canary m a coal mine, hemoglobin in red blood cells revea} the Ievel of
blood glucose ov~r a two to three month period. Toe greater the percentage ~f sugar that 1s the blood supply, the higher the percentage ofhemoglob_m has been glycosylated. Note that the percentage ofhemoglobin
~atls glycosylated is invariant to day-to-day blood sugar Ievels (Woerle,
Punenta, Meyer, Gosmanov, Szoke, Szombathy Mitrakou &amp; Gericb
2004). Thus, it is an excellent measure of health ;tock in the Grossman
sense (Grossman 1972).
The American Diabetes Association defines type 2 diabetes as manª?ed based o~ glycosylated hemoglobin levels (Hbalc) (http://www.
diabetes.org/diabetes-research/summaries/woerle-ogtt.jsp). Hba 1c Ievels
?f seven percent or less indicates that the person with diabetes is managmg bis or her diabetes.
Among persons without diabetes, lower Hbalc levels should not
be con:elated with_labo~ market success. On the other hand, among persons diagnosed w1th diabetes, labor productivity for persons with Iow
Hbalc leve!s should be higher than for persons with high Hbalc levels.
~ altematJve hypothesis is that time and effort expended on managing
~abetes may come at the expense of current, short-run labor productiv~ty. Thus, it may be that e:fforts to manage diabetes lower productivity
ID the short-term.
Our strat~gy to t~st the hypothesized association oflow wages with
unmanaged diabetes mvolves creating an interaction term between diabetes an~ Hbalc levels. For persons without diabetes, the interaction term
value 1s zero. For person with diabetes, the interaction term will be their
~ale. !herefore, those who bave managed their diabetes will have an
:t~c_non term_value ofseven or lower, those who have not managed
etr diabetes will have an interaction term value of greater than seven.
We expect to find a negatively relationship between this interaction term
and log wage.

�182 /

Diabetes and Employment Productivity: Does Diabetes Management Matter?

Data and Methods
Toe data for this study comes from an ongoing survey in Brownsville,
Texas, a metropolitan area with a total population of 139,722 in 2002 that
is located in the US-Mex.ico border region (U.S. Census Bureau 2006).
Brownsville is the most southernmost city in Texas and 91.3% of its
population is ofHispanic origin (U.S. Census Bureau 2006).

Revista Perspectivas Sociales I Social Perspectives primaveralspring 2007. Vo/.9, Num. / I

183

sample selection bias, we also estimate the log wage equation using the
method of Heckman. Following Greene ( 1990), let z = 1
when the wage is known, z = Ootherwise. Toen, a probit model

z; = e,~+ Diab; X Hbalca1 + U¡, U~ N[O, l],
z

= 1 if z• &gt; O,

(1)
(2)

z = o if z.. ~ o,

Brownsville, as many other Texas border cities, is characterized by
high poverty levels and low educational attainment. For example, 36.5%
of people in Cameron County, where Brownsville is located, live below
the poverty level (which ranks it next to last in the country). Only 60% of
the population 25 years and over have completed high school (which ranks
it last in the country). Approximately 46.5% ofchildren under 18 years are
below the poverty level, which ranks it next to last in the country (http:
//www.census.gov/acs/www/Products/Ranking/2003/RO 1T050 .htm).
Even though median household incomes in Brownsville are among
the very lowest in the country, there is variation. Therefore, the Diabetes
Impact Study selected a representative sample based on income for the
Mex.ican-American population of Brownsville. To do so, we selected
census blocks from census tracts with median household incomes in the
first and the third quartiles. 1 Toe 2000 United States Census of Population and Housing was used to select the probability sampling frame.
A multi-stage cluster sample of participants is being collected in these
two Brownsville area locations and it is expected to be complete by the
beginning of 2008.
Within all randomly selected clusters (census blocks), all the households in the census block are contacted. A participant, between 35 to 64
years old, from each household is randomly selected using a ten digit
permutation algorithm.

Heckman Model
Brown m, Pagán &amp; Bastida (2005) show that especially for MexicanAmerican men, diabetes a:ffects work propensity. For persons not working
the wage is missing due to selection. Therefore, in order to account for
1Note that households selectedwithin the census tracts may have differing income /eve/s.

Prob[z = 1] = ~(C:6 + Dial&gt;; x Hbalcn1),
Prob[z =

º'= ~«.s +
1-

Diab, X Hbalcn1)

estimates the probability that wage is observed. In (1), ci is the vector of
exogenous variables related to observing wage and iS is the corresponding
vector of coefficients. Diab¡ x Hba le; is the interaction term and 'Y1 is
the associated coefficient. Note that diabetes may be related to whether
the person earns a wage or not because he or she may select out of the
market.
Toe Heckman model is a two-stage model, where equation (1) is
the first stage. Toen, the log wage equation is estimated in the second
equation as,
Log Wage = ~jJ + Diab;

x Hbalc,-"f + e;, observed only if z = 1,
(u,e)

(3)

~biw.riate normal[O, O, l ,u. ,p]

where Pis the correlation between e; and u ¡ and q e is the variance of
the disturbance (1).
Vector X; is the exogenous variables related to wage and fJ is the corresponding vector of coefficients.
It is shown in Greene ( 1990) and elsewhere that
E(Log wagelz. = IJ= z/J + Diab;

X

Hbal.cy + po-,Á(C:ó + Diab; X Hbalca1),

( 4)

where ,\ = 'P(C:-6 +Diabn1)/cl&gt;(uf,-6+ Diaba1) is the inverse Milis ratio. ef&gt; is the
marginal probability from the normal distribution and ~ cumulative

�184 /

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Diabetes aruJ Emp/oymenl Productivity: Does Diabetes Management Matter?

probability from the normal distribution.

Table 1: Descriptive statistics, by gender

Quantile Regression

Variable
n
Log hourly wage
121
Employed (l=yes; O=no)
205
Age
205
Age squared
205
Bom in Mexico (1 =yes; O=no) 205
Years of schooling
205
Years residing in Brownsville (US) 205
Married (1 =yes; 0=no)
205
Log of other household income
205
DiabeticxHbal c
190
Diabetic (1 =yes; O=no)
205
''New" Diabetic (l=yes; O=no) 205

Mean
2.119
.722
47.195
2,318
.659
10.307
21.868
.600
2.871
1.367
.166
.044

Variable
Log hourly wage
Employed (l=yes; 0=no)
Age
Age squared
Bom in Mexico (l=yes; O=no)
Years of schooling
Years residing in Brownsville (US)
Married (1 =yes; O=no)
Log of other household income
DiabeticxHbal e
Diabetic (1 =yes; 0=no)
''New" Diabetic (l=yes; 0=no)

Women
Mean S.D.
1.947 .479
.482
.500
47.256 8.934
2,313
868
.721
.449
9.028 4.218
21.811 15.851
.517
.500
5.164 4.562
1.336 3.647
.136
.343
.041
.200

We estimate log wage quantile regressions for the following equation,
Log wage = rJJ + Diab; X Hbalcy + e;,

(5)

where Diab¡ is the dummy variable defined above and Diab; x Hbalc¡
is the interaction term (Koenker &amp; Hallock 2001). Vector X; is the exogenous variables related to wage and /3 is the corresponding vector of
coefficients, as defined in (3). Other versions of (5) that will be estinlated
include the diabetes dummy variable without the interaction term.
Quantile regression is useful for two reasons. First, diabetes and
managed diabetes may affect productivity differently at different levels
of the wage distribution. Second, our data is highly compressed at the
low end of the wage distribution and wages may be constrained from
falling further due to diabetes.

\

We estimate the simultaneous quantile regression with the 'sqreg'
function in Stata Version 8 (Stata 2003). Confidence intervals are constructed at each quantile via boot-strapping. The quantiles selected are
from .05 to .95, in steps of 0.05. Thus, 19 simultaneous quantile regressions were estimated.

Results
Table 1 reports the descriptive statistics of the variables used in the OLS,
Heckman, and quantile regressions by gender. Note that women are less
likely to be employed and have

n
177
434
434
434
434
434
434
433
433
408
434
434

185

Men
S.D.
Min Max
.523
1
4
.449
o 1
9.564 21 64
919
4414,096
.475
o 1
4.302 o 20
17.399 o 63
.491
o 1
4.338 o 13
3.577 o 16
.373
o 1
.205
o 1

Min Max
1
4
o 1
35 64
1225 4,096
o 1
o 20
o 64
o 1
o 12
o 19
o 1
o 1

slightly less schooling than meo, and are more likely to be immigrants.
Men are also paid more than women.
Approximately four percent of women and men not previously
diagnosed with diabetes had fasting glucose levels above 126 mg/
dl. This is the variable labeled "New Diabetic." Although a second
reading would be necessary to officially diagnose diabetes, the vast

�186 / Diabetes and Emp/oyment Productívity: Does Diabetes Management Matter?

Revista Perspectivas Sociales / Social PeT$JH!Clives primavera/spring 2007. Vo/.9, Num. J /

ma jority ofthem likely have diabetes and have therefore been diagnosed
for the first time by the medical personnel in our survey.

is related to working and productivity in a non-linear fashion. Being bom
in Mexico has a negative effect on wages. Toe variable

Table 2: Self-management ofDiabetes, by gender

Table 3: OLS model oflog wage, Men

n

Var
Hbalc
Bloodsugar

54
59

Hbalc
Blood sugar
332.5

26
34

S.D.
Women
10.1
3.5
200.98 82.04
Men
2.7
9.98
73.7
189.02

Mean

Min Max

4.7 18.9
74.3 434
5.8 16.2
84.l

Of people with diabetes, women are no more likely to have their
Hba 1e managed in comparison tomen. However, neither gender appears
to be managing their diabetes effectively.
Based on our previous research (Brown ID et al. 2005), we also
estimated the correlation between the interaction term and our instruments (family history of diabetes) using a tobit model (not reported).
However unlike the correlation between diabetes status and family his'
tory of diabetes,
the correlation between the interaction term and family
history of diabetes was weak.2 This is likely because although genetics
explains much of the variation of whether a person develops diabetes,
diabetes-related genetics does not explain whether a person with diabetes is able to have it managed. Dueto the weak correlation between
our instruments and our interaction term, we will not use instrumental
variable techniques to examine diabetes management.

Variable

Coefficient Std. Err. Coefficient
Log hourly wage
Age
- 0.105 ** 0.051
-0.107 **
Agesquared
0.001 ** 0.001
0.001
**
Boro in Mexico
( l =yes; O=no) -0.279 ** 0.137
- 0.260 **
Years of
schooling
0.031 ** 0.013
0.033
**
Years residing
in Brownsville {US)-0.004
0.004
-0.003
Married
(1 =yes; O=no) 0.181 * 0.101
0.1 70 *
DiabeticxHbalc -0.019
0.018
Diabetic
(1 =yes; 0=no)
-0.278 *
Constant
4.169 *** 1.176
4.207 ***
Significance levels: *: 10% **: 5% ***: 1%

187

Std. Err.
0.049
0.001
0.126
0.012
0.004
0.096

0.151
1.152

'years of schooling' is positively related to wage. Being married is
positively related to wage at the 10% level. Finally, the variable 'years
in Brownsville' is negatively related to log wage. For most people, the
number ofyears residing in Brownsville is synonymous with the number
of years in the United States. The negative sign likely re:flects the fact
that the border area is a temporary place of residence for many Mexican
Americans. Many who develop language and other work sk:ills move
away from the border to places in the U.S.

OLS and Heckman Models
Table 3 reports the estimates for the OLS regression formen, assuming
that diabetes is exogenous. Let us first consider the model in the leftmost
columns, where diabetes management is considered. Age and age squared
2

The results are available upon request.

Diabetes management (the interaction term, DiabeticxHbalc)
coefficient is negatively related to log wage, but the association is not
statistically significant at this level ofpower. However, this suggests that
diabetes has a detrimental e:ffect on productivity, even when managed.
Let us now consider the model in the rightmost columns, where diabetes
per se is considered. Diabetes is negatively related to log wages. Toe

�188 /

Diabetes an,J Employment Producffvity: Daes Diabetes Management Matter?

wage premium is quite high-having diabetes lowers wages by 28%.

Table 4: Heckman model oflog wage, Meo

In order to take sample selection into account, let us now turn our
attention to the Heckman model estimates in Table 4. Age and age
squared are now not significantly related to log wage. In both the selection equation and the wage equation, the diabetes Hbal e interaction term
is significantly and negatively related to working and negatively related
to log wage. Further, the magnitude of the effect ofthe diabetes Hbalc
interaction term is approximately twice the effect when sample selection
is not taken into account.
For each unit increase of Hbalc for persons with diabetes, log wage
declines by four percentage points.

Variable

Even though diabetes management is negatively associated with
productivity, diabetes status has a stronger association. After accounting for sample selection, the negative effect of diabetes on productivity
increases by approximately 50%, from 28% to 42%.
Note that diabetes is negatively related to earning a positive wage.
Being married is positively related to earning a positive wage; Log
of other household income is negatively related to eaming a positive
wage.

\

Table 4 also includes a likelihood ratio test of the covariance between
ei and u;, defined as pin equation (3). In each specification of the model,
the error terms are correlated at the 10% level. This indicates a bivariate normal distribution of the sample selection and log wage equations.
Therefore, the Heckman estimates are warranted.
Table 5 reports the estimates for the OLS regression for women, assuming that diabetes is exogenous. Only the variables 'years of schooling'
'years in Brownsville' are positively related to wage. Being married is
positively related to wage at the 10% level.
Diabetes management (the interaction tenn, DiabeticxHbalc) coefficient is negatively related to wage, but not statistically significant.
This suggests that diabetes has a detrimental effect on productivity, even
when managed. Toe results are similar to those for men. Diabetes per se

189

Revista Perspectivas Sociales/ Social Perspectives primaveralspring 2007. Vol.9, Num. J/

Coefficient Std. Err. 1 Coefficient
Log hourly wage
-0.069
0.056
- 0.081
0.001
0.001
0.001

Std Err.

Age
0.055
Agesquared
0.001
Born in Mexico
(l=yes; O=no)
-0.269 *
0.146
-0.282
**
0.135
Years of schooling 0.027 ** 0.014
0.028
**
0.013
Years residing in
Brownsville (US) -0.003
0.004
- 0.003
0.004
Married
(!=yes; O=no)
0.291 *** 0.108
0.289
***
0.104
DiabeticxHbalc - 0.040 **
0.018
Diabetic
(1 =yes; O=no)
***
- 0.422
0.158
Constant
3.193 **
1.316
3.506
***
1.278
Wage Observed (1 =yes; O=no)
Age
0.174
0.118
0.146
0.117
Agesquared
-0.002 *
0.001
- 0.002
0.001
Born in Mexico
(l=yes; O=no)
-0.197
0.279
-0.290
0.266
Years of schooling 0.014
0.026
0.007
0.025
Years residing in
Brownsville (US) -0.004
0.008
-0.006
0.008
Married
(l=yes; O=no)
0.751 *** 0.206
0.805 ***
0.201
Logof other
household income -0.075 *** 0.023
- 0.079 ***
0.022
DiabeticxHba le -0.074 ** 0.030
Diabetic
(l=yes; O=no)
-0.638 **
0.280
Constant
-3.251
2.749
-2.455
2.725
Ho: P =O
(X2 (1) = 3.08, Prob = 0.079 X2 (1) =3.27, Prob = 0.071
Significance levels: *: 10% **: 5% ***: 1%

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Table 5: OLS model oflog wage, Women

Table 6: Heckman model oflog wage, Women

l

Coe:fficient Std. Err.
Coefficient Std. Err.
Log hourly wage
0.030
0.050
Age
0.011
0.051
0.000
0.001
Age squared 0.000
0.001
0.083
Boro in Mexico (l==yes; O=no) - 0.071
0.085 - 0.064
0.024
***
0.009
Years of schooling
0.020 ** 0.009
0.009 *** 0.003
Years residing in Brownsville (US) 0.009 *** 0.003
0.067
0.068
Married (l==yes; O=no)
0.091
0.069
DiabeticxHbalc
- 0.014
0.009
- 0.160
0.099
Diabetic (1 ==yes; O=no)
0.828
1.165
Constant
1.284
1.181
Significance levels: *: 10% **: 5% ***: 1%

Variable

is negatively related to log wages, but not at any statistically significant
level. Toe wage premium is much lower than for women.
Table 6 shows the Heckman results for women. The likelihood ratio
test of whether p , which is the correlation between e¡ and u¡ in (3), is
significantly different from zero does not revea! a difference. Therefore,
the results for the wage equation are again equivalent to OLS estimates
with no selection.

Quantile Regression
In order to consider the effect of diabetes management on
productivity, we estimate log wage quantile regressions. Figures 1,
2, and 3 display the results. For each (A) figure (on the left), the line
represents the diabetes coe:fficient estímate and its 95% confidence
interval for each quantile of log wage. These are from equation (5).
The dotted line is the zero coe:fficient. For each (B) figure (on the
right), the line represents the diabetes Hbalc interaction coefficient
estímate and its 95% confidence interval for each quantile of log
wage. These are from equation (5). Note that the other regressor are the
same as above (Constant, Age, Age squared, Boro in Mexico (1 ==yes;
O=no), Years of schooling, Years residing in Brownsville (US), Married
(l=yes; O==no)).

191

Variable

Coefficient Std. Err. Coefficient Std. Err.
Log hourly wage
Age
0.004
0.050
0.025
0.050
Age squared
0.000
0.001
0.000
0.001
Boro in Mexico {l=yes; O=no) -0.078
0.084 -0.068
0.081
Years of schooling
0.019 ** 0.009
0.023 *** 0.008
Years residing in
Brownsville (US)
0.009 *** 0.003
0.009 *** 0.003
Married (1 =yes; O=no)
0.100
0.068
0.075
0.068
DiabeticxHbalc
- 0.014
0.009
Diabetic (1 =yes; O=no)
- 0.163 *
0.097
Constant
1.511
1.194
0.996
1.182
Wage Observed (l=yes; O=no)
Age
0.143
0.090
0.151 *
0.088
Age squared
- 0.002 * 0.001 -0.002 *
0.001
Boro in Mexico (l=yes; O=no) 0.051
0.172
0.042
0.165
Years of schooling
0.024
O.O 18
0.026
0.017
Years residing in
Brownsville (US)
0.002
0.005
0.001
0.005
Married (l=yes; O=no)
0.185
0.141
0.130
0.137
Log ofother household income -0.109 *** 0.015 -0.108 *** 0.015
DiabeticxHbalc
0.012
0.019
Diabetic {l=yes; O=no)
0.205
0.193
Constant
-3 .104
2.127 -3.320
2.081
X2 (1) =0.52 Prob= 0.4704 (X2 (1) = 0.27 Prob = 0.6064
Significance Ievels: *: 10% **: 5% ***: l %

Let us first consider the effects of diabetes on men and women
combined, as shown in column A of Figure 1. The results show that the
detrimental effects of diabetes are higher at the higher wage quantiles.
This could indicate that 'left wall' effects at the low end of the wage because they are already at the lowest possible wage for their profession.
As shown in column B of Figure 1, when the interaction term is
included rather than the diabetes dummy, most ofthe detrimental effects

�192 / Diabetes ami Employmenl Productivity: Does Diabetes Management Matter?

Revista Perspectivas Sociales/Social Perspectives primaveralspring 2007. l'o/.9, Num. J /

on labor productivity disappear.
low end of the wage distribution may be less productive than persons distribution. In reality, persons with diabetes (managed or
not) at the without diabetes, but this &lt;loes not translate to wages

Figure 2: Women: (A) Diabetes (B) Diabetes xHbalc

This indicates that persons with diabetes who have managed their
diabetes are no more productive than persons with diabetes who have
not managed their diabetes. Note that when the diabetes dummy and the
interaction term are both included, neither affects diabetes at any portion
of the log wage distribution.

i

ó

!

~

:

!"!

1
~

~

193

o

..

.

-

..

;

Figure 3: Men: (A) Diabetes (B) Diabetes xHbalc

-

Figure 1: Men &amp; Women: (A) Diabetes (B) DiabetesxHbalc
~

2
&amp;

§

§

i,ó

I;

h'I

g
'I

i

'I

..

A

-

-

~ -

a.s

g~

..

~

;

..

.

..

~

,.

;¡

~

2

°'""""

Let us now consider women, as shown in Figure 2. Column A of
Figure 2 illustrates

1

the estimates of diabetes on labor productivity. 1bis indicates that the
detrimental effects of diabetes are higher in the higher wage quantiles.
However, when Hbal e management is taken into account, most of the
detrimental effects of diabetes on labor productivity disappear. Note that
when the diabetes dummy and the interaction term are both included,
neither affects diabetes at any portion of the log wage distribution.
Formen, as shown in Figure 3, diabetes has a large effect on productivity, whether or not we include the diabetes dummy or the interaction
term. However, the effects do not differ by the quantile of the wage.

4 Discussion and Conclusion
Our results reported above are inconsistent with previous research suggesting that diabetes mainly affects the labor market of men, but not
women (Bastida &amp; Pagán 2002, Brown III et al. 2005). Ourresults using
quantile regression revea] that at the high end ofthe wage distribution, the

�194 / Diabetes anti Emp/oyment Productivity: Does Diabetes Managemenl Matter?

Revista Penpeclivas Sociales I Social Penpectives primaveralspring 2007. Jlo/.9, Num. J/

productivity of females with diabetes is lower than for females without
diabetes. This is possibly due to tbe fact that women with diabetes earn
wages near the left-wall of the wage distribution.

References

Our results for Hispanics also are higher quantitatively than previous
research. Formales, the wage productivity premium for avoiding diabetes
is approximately 42%. For tbose witb diabetes, there is an approximately
four percentage point wage premium for every unit ofHbalc increase.
Our results suggest that in order to avoid productivity losses for males
associated with diabetes, scarce prevention resources should be spent on
the prevention ofonset of diabetes rather than tbe management ofHbal e
for those already diagnosed with diabetes.

195

American Diabetes Association (2003). 'Economic costs of diabetes in
the U.S. in 2002 ', Diabetes Care 26(3), 917-932.
Bastida, E. &amp; Pagán, J. A (2002), 'The impact of diabetes on adult
employment and eamings ofMexican-Americans: Findings from a community based study', Hea/th Economics 11 (5), 403-13.
Brown III, H. S., Pagán, J. A. &amp; Bastida, E. (2005), 'Toe impact of
diabetes on employment: Genetic IVs in a bivariate probit', Health
Economics 14(5), 537-544.

Unfortunately, this means resources must be spread among populations most predisposed to diabetes, sucb as Hispanics, rather than
concentrated on the smaller group with diabetes. This is not to say that
management of diabetes will not improve quality of life or prevent medica! costs in the future. Productivity in the future will likely be higher for
those who currently are managing their diabetes.

Greene, W. H. (1990). Econometric Analysis, Macmillan Publishing,
NewYork.

Our results on self-management of diabetes are valid in the short-run
only. The Grossman model suggests that bealth capital leads to longrun productivity gains. However, we only compare short-run effects of
diabetes management with cross-section data.

Kahn, M. (1998). 'Health and labor market performance: Toe case of
diabetes', Journal ofLabor Economics 16(4), 878-899.

Grossman, M. (1972). The Demandfor Health: A Theoretical and Empirical lnvestigation, Coumbia University Press (National Bureau for
Economic Research).

Koenker, R. &amp; Hallock, K . F. (2001 ). 'Quantile regression', Journal of
Economic Perspectives 15(4), 143- 156.
Lavigne, J. E.; Phelps, C. E., Mushlin, A. &amp; Lednar, W. M. (2003); 'Reductions in individual work productivity associated with Type 2 diabetes
mellitus', Pharma-coeconomics 21(15), 1123- 1134.
Ng, Y. C.; Jacobs, P.; &amp; Johnson, J. A. (2001). 'Productivity losses associated with diabetes in the U.S. ', Diabetes Care 24(2), 257-261.
Stata (2003). Stata Reference Manual [computer program]. Version 8,
1-4 edn, StataPress.
U.S. Census Bureau (2006), American Factfinder, Technical report, U.S.
Census Bureau. generated by Shelton Brown.

�196 /

Diabetes and Emp/oyment Productivity: Does Diabetes Managemenl Matter?

Woerle, H. J.; Pimenta, W. P.; Meyer, C., Gosmanov; N. R., Szoke; E.,
Szombathy, T., Mitrakou, A. y Gerich, J. E. (2004). 'Diagnostic and
Therapeutic Implications of Relationships Between Fasting, 2-Hour
Postchallenge Plasma Glucose and Hemoglobin A le Values', Arch
lntern Med 164(15), 1627- 1632.

GUIDELINES FOR
CONTRIBUTORSNORMAS DE PRESENTACIÓN
DE ARTÍCULOS

�Revista Perspectivas Sociales / Social Perspectives primavero/spring 2()()7. Vol.9, Num. J I

199

GUIDELINES FOR CONTRIBUTORS OF 'SOCIAL
PERSPECTIVAS/PERSPECTIVAS SOCIALES'
Social Perspectives/Perspectivas Sociales, a bilingual, bi-nationaljournal, is seeking manuscripts to be published in 2008. Toe journal is a joint
project ofthe Facultad de Trabajo Social and the Facultad de Economía of
the Universidad Autónoma de Nuevo Leon, Mexico, the School ofSocial
Work at the University of Texas at Austin and The University of Texas
atArlington, the School ofSocial Work at the University ofTennessee
and the Facultad de Trabajo Social de la Universidad Juárez del Estado
de Durango. We are seeking papers that focus on issues connected to the
U.S.-Mexico border and the persons moving in both directions across
that border, social work practice issues that are common to individuals,
families and communities in both nations, social policy issues that are
common to both nations, social work education relevant, and research
on social conditions.
Papers describing innovative practices, empirical research, policy and
program developments are welcomed. Interdisciplinary and intemational
papers are encouraged.

Contributions should adjust to the following rules:
1. Contributions submitted must be original and should not be under
consideration in any other journal
2. Contributions should be submitted electronically to one of the
following e-mail addresses: veronikasieglin@yahoo.de; lorikay@
mail.utexas.edu; or to mramor@facts.uanl.mx. Toe journal prefers
Microsoft Word for Windows.
3. Author(s)' information (author(s)' name, academic degree, affiliation
including telephone, postal address and e-mail address) should be
typed on a separate sheet.
4. All papers deemed appropriate for the joumal are sent out
anonymously to two referees of the Scientific Board of the journal
thatconsists ofan intemational panel. Contributions will be published
only if they are accepted by the referees.
5. Contributions will be published in English or Spanish. Papers should
not be shorter than 1Opages and longer than 30 pages. They should
be typed 1.5 spaced, Times New Roman. Avoid fancy typefaces.

�Revista PerspecJivas Sociales / Social Perspectives primavera/spring 2007. lk&gt;l.9, Num. / /

200

6.
7.
8.

9.

Use cursive type font only for foreign words.
Toe typical manuscript is about 20 pages including references, and
abstract (300-350 words) in English and Spanish.
Include a brief abstract (300-350 words) summarizing the findings
and fi.ve key words.
Textual quotations should use quotation marks instead of cursive
letters. Please indent any citations in the body of the text that are
longer than four lines as a block quotation; give them a deeper indent
than the rest of your text.
References must be presented at the end of the paper in a separate
References section as followed: author (family name, name), (year),
title, place, editorial.

Examples:
a) Books
Edelman, P.; H.J. Holzer, and P. Offner (Eds.). (2006). Reconnecting
disadvantaged young men, Washington DC, Urban Institute Press.
Russo, R.J. (1980). "State problems and the need for research-based
planning in the drug fi.eld", In C. Akins, and G. Beschner (Eds.), Ethnography: A research tool for policymakers in the drug and alcohol
fields, Rockville, Maryland, U.S. Department of Health and Human
Services, pp. 40-65.

\

b) Journal Articles:

Murray, D.M.; R.V. Luepker, C.A. Johnson, andM.B. Mittelmark(1984).
"Toe prevention of cigarette smoking in children: A comparison of four
strategies", Joumal ofApplied Psychology, 14(3), pp. 274-288.
c) Inforrnation from web-sides:
McBride, D. C.; C.J VanderWaal, Y. M. Terry, and H. VanBuren (1999).
Breaking the Cycle ofdrug use amongjuvenile offenders [On-line]. Retrieved October 24, 2002, from http://www.ncjrs.org/pdffiles 1/179273.
pdf
10. Write sentences and paragraphs clearly and succinctly with a

201

minimum of jargon. Writing should demonstrate theoretical
soundness and scientific accuracy.
11. Authors will be notified after the reviewers return their comments
to the editors. Toe results of the reviewers may be in any of these
terms: publishable as it is, not publishable, or publishable with
commendations and/or modifications.
12. Toe articles published in Perspectivas Sociales/Social Perspectives
may be distributed in any press or electronic format that the editorial
committee considers pertinent.

�202

NORMAS DE PRESENTACIÓN DE COLABORACIONES
PARA 'PERSPECTIVAS SOCIALES/ SOCIAL PERSPECTIVES'
Perspectivas Sociales/Social Perspectives es una revista bilingüe y binacional que invita a trabajadores sociales y científicos sociales a someter
manuscritos para ser editados durante el 2008. La revista constituye un
proyecto conjunto de la Facultad de Trabajo Social y de la Facultad de
Economía de la Universidad Autónoma de Nuevo León, México, Toe
School ofSocial Work at the University ofTexas atAustin y Toe University of Texas at Arlington, the School of Social Work of the University
ofTennessee y de la Facultad de Trabajo Social de la Universidad Juárez
del Estado de Durango. Buscamos artículos que se enfocan en temas
relacionadas con la frontera México-Estados Unidos y las personas
que se desplazan en ambas direcciones; tópicos de importancia p~ra la
práctica del trabajo social en torno a individuo, familia y comumdad;
las políticas sociales, la formación del trabajo social; e investigacio~es
científico-sociales acerca de las condiciones sociales. Se da una especial
bienvenida a trabajos que analizan prácticas innovadoras, presentan
resultados de estudios empíricos y que revisan críticamente políticas Y
programas de desarrollo social. Se alienta asimismo a trabajos interdisciplinarios e internacionales.

\
\

t

Los artículos deben ajustarse a las siguientes normas de presentación
de originales:
1. Los documentos deberán ser versiones definitivas e inéditas.
2. Los trabajos se enviarán por correo electrónico en formato
Microsoft® Word a alguna de las siguientes direcciones electrónicas
veronikasieglin@yahoo.de ó lorikay@mail.utexas.edu .
3. Deberá enviarse, en un documento anexo llamado "Datos del autor",
la siguiente información: nombre completo, grado universitario
máximo, institución donde labora, cargo actual que desempeña,
número telefónico, dirección postal, dirección electrónica En el caso
de coautorías deberán indicarse los datos de todos los colaboradores.
4. Las colaboraciones serán evaluadas por la dirección de la revista para
verificar que se ajusten a las presentes normas. De ser así, serán
enviadas a dos dictaminadores miembros del Comité Científico de

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5.

6.
7.

8.

9.

203

· la revista, cuyo arbitraje favorable es requisito indispensable para
la publicación del trabajo.
Los artículos se publican en inglés o español con un resumen en
ambos idiomas. Los manuscritos deben tener como extensión mínima
1Opáginas y máximo 30, en fuente Times New Roman, interlineado
de 1.5, sin macros ni viñetas de adorno, sin hacer énfasis con fuentes
tipográficas, y utilizando cursivas sólo para voces extrajeras.
El manuscrito típico tiene alrededor de 20 páginas incluido el
resumen (300-350 palabras), y la bibliografia.
Los artículos iniciarán con un resumen (300-3 50 palabras) e incluirán
cinco palabras clave.
Las citas textuales se consignarán entre comillas, no mediante
cursivas. Cuando se trate de citas breves, se mantendrán dentro
del párrafo en que se produzca la referencia; si la cita rebasa las cuatro
líneas, se colocará a bando, con márgenes más amplios, a un espacio
y sin entrecomillado.
La bibliografía irá al final del artículo en este orden: autor
(apellidos, nombre), año (entre paréntesis), obra (en cursiva), lugar
de edición, editorial.

Ejemplos.
a) Libros

Bauman, Zygmunt (2002). La ambivalencia de la modernidad y otras
conversaciones; Barcelona, Paidós.
Adelantado, José, José Antonio Noguera y Xavier Rambla (2000). "El
marco de análisis: las relaciones complejas entre estructura social y
políticas sociales", en José Adelantado (coord.), Cambios en el Estado
de Bienestar, Barcelona, Editorial Icaria, pp. 23-60.
b) Revistas:
Boltvinik, Julio (octubre 2001 ). "Opciones metodológicas para medir la
pobreza en México", en Revista Comercio Exterior, vol. 51, núm. 10,
México DF, pp. 869-878.
e) Sitios de Internet:

�204

Cámara Nacional de la Industria Tequilera (2004). Jnforme de la Cámara

Nacional de la Industria Tequilera sobre su comportamiento durante el
año de 2005, México. Disponible en: http:J/www.camaratequilera.com.
mx/ (Recuperado el 19/10/06).
1O. Respetando el estilo de cada escritor, sugerimos redactar los textos a
través de construcciones sintácticas sencillas, párrafos
preferentemente breves y articulación entre profundidad teórica,
rigor científico y claridad expositiva.
11. Una vez emitidas las evaluaciones de los árbitros consultados, se
comunicará al autor los resultados del dictamen en cualquiera de
los términos siguientes: se publica, no se publica o se publica con las
recomendaciones o modificaciones que se consideraron
pertinentes.
12. Los artículos publicados en Social Perspectives/Perspectivas
Sociales serán difundidos y distribuidos por todos los medios
impresos y/o electrónicos que el Comité Editorial de la revista juzgue
convenientes.

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\

Estado/State l._______,

País/Country .___ _ _ _ _ _ ___. C.P./ZIP
Teléfono/Phone

\¡

Correo electrónico/E-mail
• Adjunto mi cheque certificado o giro postal a nombre de
la Facultad de Trabajo Social de la Universidad ~ - - - - - - ~
Autónoma de Nuevo León por la cantidad de$ L--- - - - - - - - '
• 1 send check payable to Facultad de Trabajo Social,
Universidad Autónoma de Nuevo León for $
~------~
* Para envío al interior de la República, se deberá agregar 160.00 pesos por gastos
de envío (cubre /os dos números). En caso de envíos fuera de la República se necesitará
calcular /os gastos según el país.

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