Assistant Professor of Economics
Faculty Fellow, Institute for Policy Research,
Northwestern University
PhD, Economics, New York University, 2003
rbernal@northwestern.edu
Curriculum Vitae

Bernal is a labor economist with a particular interest in the determinants of an individual’s performance in the labor market and in particular, the determinants of ability at early stages of life. Current research projects include estimation of structural models of women’s employment, child care choices and the effects of these decisions on children’s cognitive ability as well as an estimation of the effects of child care quality and parents’ specific time allocations on children’s development. Discrete choice models and structural estimation using micro-level data are important components of her research.

Current Projects

The Effect of Maternal Employment and Child Care on Children's Cognitive Development. In this paper, Bernal develops and estimates a dynamic model of employment and child care decisions of women after childbirth in order to evaluate the effects of maternal employment and daycare choices on children's cognitive ability. She uses data from the NLSY to estimate the model. Her results indicate that the effects of maternal employment and child care on children's ability are negative and rather sizable. In fact, having a full-time working mother who uses child care during one of the first five years after childbirth is associated with a 1.8 percent reduction in the child's test scores. Based on the estimates of the model, Bernal evaluates the impact of policies related to parental leave, child care and other incentives to stay at home after childbirth on women's decisions and children's outcomes.

Parental Leave Policies, Welfare, and Income Distribution. Bernal and Anna Fruttero at the World Bank are using a general equilibrium model of marriage and divorce to assess how public policies on maternity and paternity leave and leave benefits affect intrahousehold decision making, family structure, intergenerational mobility, and income distribution. The two researchers calibrated their model to replicate some characteristics relevant to the interaction between the marriage and labor market. They start with a benchmark economy characterized by a minimal time investment required to participate in the labor market calibrated to U.S. data. They then analyze how this economy is affected by different parental leave policies: unpaid leave, paid-leave benefits, and mandated leave. Their results indicate that the introduction of an unpaid maternity leave is associated with an improvement in the income and utility distributions due primarily to changes in household income induced by an increase in the fraction of working females as well as an increase in the proportion of working married males that work full-time. With a paid leave, children’s human capital increases as a consequence of higher household income and higher parental time investments in children. In the case of a mandated leave, average human capital increases by as much as 9 percent with respect to the benchmark economy.

Child-Care Choices and Children's Cognitive Achievement: The Case of Single Mothers. This project, in collaboration with Michael P. Keane at Yale University, seeks to increase our understanding of the determinants of children’s cognitive ability. In particular, Bernal and Keane evaluate the effects of home inputs on children’s cognitive development using the sample of single mothers from the National Longitudinal Survey of Youth (NLSY). Important selection problems arise when trying to assess the impact of maternal time and income on children’s development. To deal with this, they exploit the (plausibly) exogenous variation in employment and child-care use by single mothers generated by differences in welfare regulations across states and over time. In particular, the 1996 welfare reform act, and earlier state policy changes adopted under federal waivers, generated substantial increases in work and child-care use. Thus, they construct a comprehensive set of welfare policy variables at the individual and state level, and use them as instruments to estimate child cognitive ability production functions.

Their results indicate that the effect of child care use is negative, significant and rather sizeable. In particular an additional year of child-care use is associated with a reduction of 2.8 percent (.15 standard deviations) in child test scores. But this general finding masks important differences across types of child care, child age ranges, and maternal education. Indeed, only informal care used after the first year leads to significant reductions in child achievement. Formal care (i.e., center-based care, preschool) does not have any adverse effect on cognitive outcomes. In fact, their estimates imply that formal care has large positive effects on cognitive outcomes for children of poorly educated single mothers. Finally, Bernal and Keane also provide evidence of a strong link between test scores at ages 4, 5, and 6 and completed education.

Quasi-Structural Estimation of a Model of Child-Care Choices and Child Cognitive Ability Production. This project, in collaboration with Keane evaluates the effects of maternal versus alternative care providers’ time inputs on children’s cognitive development using the sample of single mothers in the National Longitudinal Survey of Youth. To deal with the selection problem created by unobserved heterogeneity of mothers and children, Bernal and Keane develop a model of mother’s employment and child-care decisions. Guided by this model, they obtain approximate decisions rules for employment and child-care use, and estimate these jointly with the child’s cognitive ability production function—an approach they refer to as “quasi-structural.” This joint estimation implements a selection correction.

To help identify our selection model, they take advantage of the substantial and plausibly exogenous variation in employment and child-care choices of single mothers generated by the variation in welfare rules across states and over time—especially, the large changes created by the 1996 welfare reform legislation and earlier state waivers. Welfare rules provide natural exclusion restrictions, as it is plausible they enter decision rules for employment and day-care use, while not entering the child cognitive ability production function directly.

Their results imply that if a mother works full-time, while placing a child in day care, for one full year, it reduces the child’s cognitive ability test score by roughly 2.7 percent on average, which is 0.14 standard deviations of the score distribution. However, they find evidence of substantial observed and unobserved heterogeneity in the day-care effect. Negative effects of day care on test scores are larger for better-educated mothers and for children with larger skill endowments.