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Papers by Marcos Vera-hernández

Research paper thumbnail of Child health in rural Colombia: determinants and policy interventions

In this paper we study the determinants of child anthropometrics on a sample of poor Colombian ch... more In this paper we study the determinants of child anthropometrics on a sample of poor Colombian children living in small municipalities. We focus on the influence of household consumption, and public infrastructure. We take into account the endogeneity of household consumption using two different sets of instruments: household assets and municipality average wage. We find that household consumption is an important determinant of child health. The importance of the effect is confirmed by the two different sets of instruments. We find that using ordinary least squares would lead to conclude that the importance of household consumption is much smaller than the instrumental variable estimates suggest. The presence of a public hospital in the municipality positively influences child health. The extent of the piped water network positively influences the health of children if their parents have at least some education. The number of hours of growth and development check-ups is also an important determinant of child health. We find that some of these results only show up once squared and interaction terms have been included in the regression. Overall, our estimates suggest that both public and private investments are important to improve child health in poor environments.

Research paper thumbnail of MANAGERIAL INCENTIVES IN PUBLIC SERVICE DELIVERY Evidence from School-based Nutrition Programs in Rural China

Research paper thumbnail of Testing for Adverse Selection in the National Health Service

Research paper thumbnail of Nutrition, information, and household behaviour: experimental evidence from Malawi

Research paper thumbnail of Food for thought? Breastfeeding and child development

Research paper thumbnail of Childcare provision, its use and nutritional outcomes. Crowding out and impacts of a community nursery programme 1

In this paper, to study Hogares Comunitarios, a large childcare and food nutrition programme in C... more In this paper, to study Hogares Comunitarios, a large childcare and food nutrition programme in Colombia, we use a behavioural model of child nutrition. We consider the programme as one of the inputs in the production function of nutritional status together with female labour supply and food intake at home which is unobservable. We obtain an estimating equation whose parameters

Research paper thumbnail of Illness severity and the use of public health care by the privately insured. Is there a link?

We study the link between illness severity and the use of public health care services by the priv... more We study the link between illness severity and the use of public health care services by the privately insured under a National Health System. Our theoretical model shows that this relationship will depend on the prioritization established by the public authorities, the cost of waiting and the private doctors' strategic behavior. In our empiri- cal exercise, we find the consistent

Research paper thumbnail of How complex are the contracts offered by health plans?

SERIEs, 2010

When health plans compete under adverse selection, the competitive equilibrium set of contracts i... more When health plans compete under adverse selection, the competitive equilibrium set of contracts is unique. However, the allocation of these contracts among health plans is undetermined. We show that three health plans suffice to sustain an equilibrium where each health plan offers a single contract and attracts a single type of agent (full specialization). We also show that this equilibrium can be ruled out by introducing any horizontal differentiation, and that if in equilibrium each health plan attracts all types of agents, at least one of the health plans must do so through a menu of contracts.

Research paper thumbnail of THE SHORT-TERM IMPACT OF A CONDITIONAL CASH SUBSIDY ON CHILD HEALTH AND NUTRITION IN COLOMBIA

Research paper thumbnail of Testing for adverse selection into private medical insurance

We develop a test for adverse selection and use it to examine private health insurance markets. I... more We develop a test for adverse selection and use it to examine private health insurance markets. In contrast to earlier papers that consider a purely private system or a system in which private insurance supplements a public system, we focus our attention on a system where privately funded health care is substitutive of the publicly funded one. Using a model

Research paper thumbnail of How effective are conditional cash transfers? Evidence from Colombia

Conditional cash transfer (CCT) programmes are becoming an extremely popular tool for improving t... more Conditional cash transfer (CCT) programmes are becoming an extremely popular tool for improving the education and health outcomes of poor children in developing countries. An incomplete list of countries in which they are being implemented under the support of the World Bank and other international financial institutions includes Mexico, Honduras, Nicaragua, Brazil, Turkey and Mozambique. While the implementation details vary

Research paper thumbnail of Testing for Asymmetric Information in Private Health Insurance *

The Economic Journal, 2013

We develop a test for adverse selection and use it to examine private health insurance markets. I... more We develop a test for adverse selection and use it to examine private health insurance markets. In contrast to earlier papers that consider a purely private system or a system in which private insurance supplements a public system, we focus our attention on a system where privately funded health care is substitutive of the publicly funded one. Using a model of competition among insurers, we generate predictions about the correlation between risk and the probability of taking private insurance under both symmetric information and adverse selection. These predictions constitute the basis for our adverse selection test. The theoretical model is also useful to conclude that the setting that we focus on is especially attractive to test for adverse selection. Using the British Household Panel Survey, we find evidence that adverse selection is present in this market. * We are grateful for useful comments from

Research paper thumbnail of Early Childhood Stimulation Benefits Adult Competence and Reduces Violent Behavior

PEDIATRICS, 2011

An estimated 178 million children younger than 5 years in developing countries experience linear ... more An estimated 178 million children younger than 5 years in developing countries experience linear growth retardation and are unlikely to attain their developmental potential. We aimed to evaluate adult benefits from early childhood stimulation and/or nutritional supplementation in growth-retarded children. In Kingston, Jamaica, 129 growth-retarded children aged 9 to 24 months took part in a 2-year trial of nutritional supplementation (1 kg milk-based formula per week) and/or psychosocial stimulation (weekly play sessions to improve mother-child interaction). We assessed IQ, educational attainment, and behavior at 22 years old in 105 participants. We used multivariate regressions, weighted to adjust for loss to follow-up, to determine treatment benefits. We found no significant benefits from supplementation. Participants who received stimulation reported less involvement in fights (odds ratio: 0.36 [95% confidence interval (CI) 0.12-1.06]) and in serious violent behavior (odds ratio: 0.33 [95% CI: 0.11-0.93]) than did participants with no stimulation. They also had higher adult IQ (coefficient: 6.3 [95% CI: 2.2-10.4]), higher educational attainment (achievement, grade level attained, and secondary examinations), better general knowledge, and fewer symptoms of depression and social inhibition. Early psychosocial intervention had wide-ranging benefits in adulthood that are likely to facilitate functioning in everyday life. The reductions in violent behavior are extremely important given the high levels of violence in many developing countries. The study provides critical evidence that early intervention can lead to gains in adult functioning.

Research paper thumbnail of Are tax subsidies for private medical insurance self-financing? Evidence from a microsimulation model

Journal of Health Economics, 2008

This paper develops an empirical strategy to estimate whether subsidies to private medical insura... more This paper develops an empirical strategy to estimate whether subsidies to private medical insurance are self-financing in countries where public and private health insurance coexist. We construct a simulation routine based on a micro econometric discrete choice model that allows us to evaluate the impact of premium changes on the utilisation of outpatient and inpatient health care services. As an application, we simulate the main feature of the 1999 Spanish income tax reform that abolished the individual tax deduction for expenditures on private health insurance. We find evidence suggesting that the fiscal subsidy is far from self-financing. This result is driven by the fact that private medical insurance holders make concurrent use of public services and by the low price elasticity of the demand for policies. JEL Codes: H24, I18, C25

Research paper thumbnail of Competition among differentiated health plans under adverse selection

Journal of Health Economics, 2007

Market power and adverse selection are prevalent features of the market for pre-paid health plans... more Market power and adverse selection are prevalent features of the market for pre-paid health plans. However, most of the literature on adverse selection considers extreme cases: either perfect competition or monopoly. If instead health plans are horizontally differentiated, then (i) profits derived from each low risk are higher than from each high risk and (ii) when the profits derived from each high risk are negative (cross-subsidization), a health authority as informed as the health plans can implement a Pareto-improvement. Both local and global deviations from cross-subsidization are addressed within a Nash equilibrium framework.

Research paper thumbnail of Child health in rural Colombia: determinants and policy interventions

Economics & Human Biology, 2004

In this paper we study the determinants of child anthropometrics on a sample of poor Colombian ch... more In this paper we study the determinants of child anthropometrics on a sample of poor Colombian children living in small municipalities. We focus on the influence of household consumption, and public infrastructure. We take into account the endogeneity of household consumption using two different sets of instruments: household assets and municipality average wage. We find that household consumption is an important determinant of child health. The importance of the effect is confirmed by the two different sets of instruments. We find that using ordinary least squares would lead to conclude that the importance of household consumption is much smaller than the instrumental variable estimates suggest. The presence of a public hospital in the municipality positively influences child health. The extent of the piped water network positively influences the health of children if their parents have at least some education. The number of hours of growth and development check-ups is also an important determinant of child health. We find that some of these results only show up once squared and interaction terms have been included in the regression. Overall, our estimates suggest that both public and private investments are important to improve child health in poor environments.

Research paper thumbnail of Counts with an endogenous binary regressor: A series expansion approach

The Econometrics Journal, 2005

We propose an estimator for count data regression models where a binary regressor is endogenously... more We propose an estimator for count data regression models where a binary regressor is endogenously determined. This estimator departs from previous approaches by using a flexible form for the conditional probability function of the counts. Using a Monte Carlo experiment we show that our estimator improves the fit and provides a more reliable estimate of the impact of regressors on the count when compared to alternatives which do restrict the mean to be linear-exponential. In an application to the number of trips by households in the US, we find that the estimate of the treatment effect obtained is considerably different from the one obtained under a linear-exponential mean specification.

Research paper thumbnail of What would you do? An investigation of stated-response data

Research paper thumbnail of A practicioner's guide to evaluating the impacts of labor market programs

Research paper thumbnail of Medium-and long run effects of nutrition and child care: evaluation of a community nursery programme in rural Colombia

In this paper we evaluate the effect of a large nutrition programme in rural Colombia on children... more In this paper we evaluate the effect of a large nutrition programme in rural Colombia on children nutritional status, school achievement and female labour supply. We find that the programme has very large and positive impacts. Dealing with the endogeneity of treatment is crucial, as the poorest children tend to select into the programme. Methods like Propensity Score Matching would even yield negative estimates of the impact of the program. Our results are robust to the use of instruments that do not depend on individual household choices. We also validate our evaluation strategy by considering the effect of the program on pre-intervention variables. Further, we explore the heterogeneity of the impact of the programme. Children from the poorest backgrounds are the ones that benefit the most. JEL: C21, I12, I38 * We are very grateful to

Research paper thumbnail of Child health in rural Colombia: determinants and policy interventions

In this paper we study the determinants of child anthropometrics on a sample of poor Colombian ch... more In this paper we study the determinants of child anthropometrics on a sample of poor Colombian children living in small municipalities. We focus on the influence of household consumption, and public infrastructure. We take into account the endogeneity of household consumption using two different sets of instruments: household assets and municipality average wage. We find that household consumption is an important determinant of child health. The importance of the effect is confirmed by the two different sets of instruments. We find that using ordinary least squares would lead to conclude that the importance of household consumption is much smaller than the instrumental variable estimates suggest. The presence of a public hospital in the municipality positively influences child health. The extent of the piped water network positively influences the health of children if their parents have at least some education. The number of hours of growth and development check-ups is also an important determinant of child health. We find that some of these results only show up once squared and interaction terms have been included in the regression. Overall, our estimates suggest that both public and private investments are important to improve child health in poor environments.

Research paper thumbnail of MANAGERIAL INCENTIVES IN PUBLIC SERVICE DELIVERY Evidence from School-based Nutrition Programs in Rural China

Research paper thumbnail of Testing for Adverse Selection in the National Health Service

Research paper thumbnail of Nutrition, information, and household behaviour: experimental evidence from Malawi

Research paper thumbnail of Food for thought? Breastfeeding and child development

Research paper thumbnail of Childcare provision, its use and nutritional outcomes. Crowding out and impacts of a community nursery programme 1

In this paper, to study Hogares Comunitarios, a large childcare and food nutrition programme in C... more In this paper, to study Hogares Comunitarios, a large childcare and food nutrition programme in Colombia, we use a behavioural model of child nutrition. We consider the programme as one of the inputs in the production function of nutritional status together with female labour supply and food intake at home which is unobservable. We obtain an estimating equation whose parameters

Research paper thumbnail of Illness severity and the use of public health care by the privately insured. Is there a link?

We study the link between illness severity and the use of public health care services by the priv... more We study the link between illness severity and the use of public health care services by the privately insured under a National Health System. Our theoretical model shows that this relationship will depend on the prioritization established by the public authorities, the cost of waiting and the private doctors' strategic behavior. In our empiri- cal exercise, we find the consistent

Research paper thumbnail of How complex are the contracts offered by health plans?

SERIEs, 2010

When health plans compete under adverse selection, the competitive equilibrium set of contracts i... more When health plans compete under adverse selection, the competitive equilibrium set of contracts is unique. However, the allocation of these contracts among health plans is undetermined. We show that three health plans suffice to sustain an equilibrium where each health plan offers a single contract and attracts a single type of agent (full specialization). We also show that this equilibrium can be ruled out by introducing any horizontal differentiation, and that if in equilibrium each health plan attracts all types of agents, at least one of the health plans must do so through a menu of contracts.

Research paper thumbnail of THE SHORT-TERM IMPACT OF A CONDITIONAL CASH SUBSIDY ON CHILD HEALTH AND NUTRITION IN COLOMBIA

Research paper thumbnail of Testing for adverse selection into private medical insurance

We develop a test for adverse selection and use it to examine private health insurance markets. I... more We develop a test for adverse selection and use it to examine private health insurance markets. In contrast to earlier papers that consider a purely private system or a system in which private insurance supplements a public system, we focus our attention on a system where privately funded health care is substitutive of the publicly funded one. Using a model

Research paper thumbnail of How effective are conditional cash transfers? Evidence from Colombia

Conditional cash transfer (CCT) programmes are becoming an extremely popular tool for improving t... more Conditional cash transfer (CCT) programmes are becoming an extremely popular tool for improving the education and health outcomes of poor children in developing countries. An incomplete list of countries in which they are being implemented under the support of the World Bank and other international financial institutions includes Mexico, Honduras, Nicaragua, Brazil, Turkey and Mozambique. While the implementation details vary

Research paper thumbnail of Testing for Asymmetric Information in Private Health Insurance *

The Economic Journal, 2013

We develop a test for adverse selection and use it to examine private health insurance markets. I... more We develop a test for adverse selection and use it to examine private health insurance markets. In contrast to earlier papers that consider a purely private system or a system in which private insurance supplements a public system, we focus our attention on a system where privately funded health care is substitutive of the publicly funded one. Using a model of competition among insurers, we generate predictions about the correlation between risk and the probability of taking private insurance under both symmetric information and adverse selection. These predictions constitute the basis for our adverse selection test. The theoretical model is also useful to conclude that the setting that we focus on is especially attractive to test for adverse selection. Using the British Household Panel Survey, we find evidence that adverse selection is present in this market. * We are grateful for useful comments from

Research paper thumbnail of Early Childhood Stimulation Benefits Adult Competence and Reduces Violent Behavior

PEDIATRICS, 2011

An estimated 178 million children younger than 5 years in developing countries experience linear ... more An estimated 178 million children younger than 5 years in developing countries experience linear growth retardation and are unlikely to attain their developmental potential. We aimed to evaluate adult benefits from early childhood stimulation and/or nutritional supplementation in growth-retarded children. In Kingston, Jamaica, 129 growth-retarded children aged 9 to 24 months took part in a 2-year trial of nutritional supplementation (1 kg milk-based formula per week) and/or psychosocial stimulation (weekly play sessions to improve mother-child interaction). We assessed IQ, educational attainment, and behavior at 22 years old in 105 participants. We used multivariate regressions, weighted to adjust for loss to follow-up, to determine treatment benefits. We found no significant benefits from supplementation. Participants who received stimulation reported less involvement in fights (odds ratio: 0.36 [95% confidence interval (CI) 0.12-1.06]) and in serious violent behavior (odds ratio: 0.33 [95% CI: 0.11-0.93]) than did participants with no stimulation. They also had higher adult IQ (coefficient: 6.3 [95% CI: 2.2-10.4]), higher educational attainment (achievement, grade level attained, and secondary examinations), better general knowledge, and fewer symptoms of depression and social inhibition. Early psychosocial intervention had wide-ranging benefits in adulthood that are likely to facilitate functioning in everyday life. The reductions in violent behavior are extremely important given the high levels of violence in many developing countries. The study provides critical evidence that early intervention can lead to gains in adult functioning.

Research paper thumbnail of Are tax subsidies for private medical insurance self-financing? Evidence from a microsimulation model

Journal of Health Economics, 2008

This paper develops an empirical strategy to estimate whether subsidies to private medical insura... more This paper develops an empirical strategy to estimate whether subsidies to private medical insurance are self-financing in countries where public and private health insurance coexist. We construct a simulation routine based on a micro econometric discrete choice model that allows us to evaluate the impact of premium changes on the utilisation of outpatient and inpatient health care services. As an application, we simulate the main feature of the 1999 Spanish income tax reform that abolished the individual tax deduction for expenditures on private health insurance. We find evidence suggesting that the fiscal subsidy is far from self-financing. This result is driven by the fact that private medical insurance holders make concurrent use of public services and by the low price elasticity of the demand for policies. JEL Codes: H24, I18, C25

Research paper thumbnail of Competition among differentiated health plans under adverse selection

Journal of Health Economics, 2007

Market power and adverse selection are prevalent features of the market for pre-paid health plans... more Market power and adverse selection are prevalent features of the market for pre-paid health plans. However, most of the literature on adverse selection considers extreme cases: either perfect competition or monopoly. If instead health plans are horizontally differentiated, then (i) profits derived from each low risk are higher than from each high risk and (ii) when the profits derived from each high risk are negative (cross-subsidization), a health authority as informed as the health plans can implement a Pareto-improvement. Both local and global deviations from cross-subsidization are addressed within a Nash equilibrium framework.

Research paper thumbnail of Child health in rural Colombia: determinants and policy interventions

Economics & Human Biology, 2004

In this paper we study the determinants of child anthropometrics on a sample of poor Colombian ch... more In this paper we study the determinants of child anthropometrics on a sample of poor Colombian children living in small municipalities. We focus on the influence of household consumption, and public infrastructure. We take into account the endogeneity of household consumption using two different sets of instruments: household assets and municipality average wage. We find that household consumption is an important determinant of child health. The importance of the effect is confirmed by the two different sets of instruments. We find that using ordinary least squares would lead to conclude that the importance of household consumption is much smaller than the instrumental variable estimates suggest. The presence of a public hospital in the municipality positively influences child health. The extent of the piped water network positively influences the health of children if their parents have at least some education. The number of hours of growth and development check-ups is also an important determinant of child health. We find that some of these results only show up once squared and interaction terms have been included in the regression. Overall, our estimates suggest that both public and private investments are important to improve child health in poor environments.

Research paper thumbnail of Counts with an endogenous binary regressor: A series expansion approach

The Econometrics Journal, 2005

We propose an estimator for count data regression models where a binary regressor is endogenously... more We propose an estimator for count data regression models where a binary regressor is endogenously determined. This estimator departs from previous approaches by using a flexible form for the conditional probability function of the counts. Using a Monte Carlo experiment we show that our estimator improves the fit and provides a more reliable estimate of the impact of regressors on the count when compared to alternatives which do restrict the mean to be linear-exponential. In an application to the number of trips by households in the US, we find that the estimate of the treatment effect obtained is considerably different from the one obtained under a linear-exponential mean specification.

Research paper thumbnail of What would you do? An investigation of stated-response data

Research paper thumbnail of A practicioner's guide to evaluating the impacts of labor market programs

Research paper thumbnail of Medium-and long run effects of nutrition and child care: evaluation of a community nursery programme in rural Colombia

In this paper we evaluate the effect of a large nutrition programme in rural Colombia on children... more In this paper we evaluate the effect of a large nutrition programme in rural Colombia on children nutritional status, school achievement and female labour supply. We find that the programme has very large and positive impacts. Dealing with the endogeneity of treatment is crucial, as the poorest children tend to select into the programme. Methods like Propensity Score Matching would even yield negative estimates of the impact of the program. Our results are robust to the use of instruments that do not depend on individual household choices. We also validate our evaluation strategy by considering the effect of the program on pre-intervention variables. Further, we explore the heterogeneity of the impact of the programme. Children from the poorest backgrounds are the ones that benefit the most. JEL: C21, I12, I38 * We are very grateful to