Intertemporal Substitution in Maternal Labor Supply: Evidence using State School Entrance Age Laws

Abstract

In this paper, I propose a new framework to study the intertemporal labor supply hypothesis. I use an exogenous source of variation in maternal net earning opportunities, generated through school entrance age of children, to study intertemporal labor supply behavior. Employing data from the 1980 US Census and the NLSY, I estimate the effect of a one year delay in school attendance on long run maternal labor supply. To deal with the endogeneity of school attendance age, I exploit the variation in child month of birth and state kindergarten entrance age laws. IV estimates imply that having a 5 year old enrolled in school increases labor supply measures for married women, with no younger children, by between 7 to 34 percent. In contrast to the results for married mothers, I do not find any statistically significant effect on labor market outcomes for single mothers or mothers of 5 year olds with additional younger children. Further, using a sample of 7 to 10 year olds from the NLSY, I investigate persistence in employment outcomes for a married mother whose child delayed school entry. The estimates suggest that delayed school enrollment has long run implications for maternal labor supply. Results point towards significant intertemporal substitution in labor supply. Rough calculations yield an uncompensated wage elasticity of 0.76 and an intertemporal elasticity of substitution equal to 1.1.Maternal labor supply, Kindergarten entry age, intertemporal substitution