Also available in the Journal of Labor Economics 29.3 (2011)
Abstract:
The authors 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 along with earlier state policy changes adopted under federal waivers, generated substantial increases in work and child care use. Thus, the authors construct a comprehensive set of welfare policy variables at individual and state levels and use them as instruments to estimate child cognitive ability production functions. They use local demand conditions as instruments as well.
The 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, children's ages, 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 and preschool) does not have any adverse effect on cognitive outcomes. In fact, these estimates imply that formal care has large positive effects on cognitive outcomes for children of poorly educated single mothers. Finally, the authors also provide evidence of a strong link between children's test scores at ages 4, 5, and 6 and their completed education.