NBER Publications by Sandra G. Sosa-Rubi

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Working Papers and Chapters

May 2009Impact of "Seguro Popular" on Prenatal Visits in Mexico, 2002-2005: Latent Class Model of Count Data with a Discrete Endogenous Variable
with Jeffrey E. Harris: w14995
We employ a latent class model to assess the impact of Mexico's Seguro Popular ("SP") program on the number of prenatal visits in a cross-sectional sample of 4,381 women who gave birth during 2002-2005. We specify an ordered probit model to permit a pregnant woman's probability of membership in one of three latent classes to depend on observed covariates. In the ordered probit model, enrollment in SP is explicitly treated as an endogenous variable. We model the number of prenatal visits, conditional upon membership in a particular latent class, as a Poisson regression. We employ the EM algorithm to reduce the computational burden of model estimation. At any iteration of the algorithm, the parameters of the model of latent class membership can be estimated separately from the parameter...
October 2007Heterogeneous Impact of the "Seguro Popular" Program on the Utilization of Obstetrical Services in Mexico, 2001-2006: A Multinomial Probit Model with a Discrete Endogenous Variable
with Omar Galarraga, Jeffrey E. Harris: w13498
Objective: We evaluated the impact of Seguro Popular (SP), a program introduced in 2001 in Mexico primarily to finance health care for the poor. We studied the effect of SP on pregnant women's access to obstetrical services. Data: We analyzed the cross-sectional 2006 National Health and Nutrition Survey (ENSANUT), focusing on the responses of 3,890 women who delivered babies during 2001-2006 and whose households lacked employer-based health care coverage. Methods: We formulated a multinomial probit model that distinguished between three mutually exclusive sites for delivering a baby: a health unit accredited by SP; a clinic run by the Department of Health (Secretaria de Salud, or SSA); and private obstetrical care. Our model accounted for the endogeneity of the household's binary decis...

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