When Should Children Start School?

Abstract

Our understanding of effects from kindergarten entrance age is complicated by at least two facts: a child’s age relative to their classmates may be just as important as their entrance age, and the choice of parents or schools to delay a child’s enrollment is likely to be correlated with entrance age effects. This paper addresses both of these issues by presenting a novel identification strategy for separately estimating effects from entrance and relative age at school entry that addresses the issue of essential heterogeneity. After first selecting a sample of children from the ECLS-K data set with quasi-random variation in entrance and relative ages, this paper then specifies and estimates education production functions for achievement. Entrance age parameters are positive, large, and persist until the spring of third grade. Relative age parameters are smaller, tend to be negative, and fade out for math achievement by third grade. The estimated parameters have the following implications for the average child in our sample: both an earlier entrance cutoff date and an earlier birth date will increase achievement if the child remains eligible. There is evidence of extreme heterogeneity in effects by gender and home environment, and these are likely to be the results most relevant for policy.

Keywords: Kindergarten entrance age, redshirting, early childhood education, essential heterogeneity

JEL Classification: H40, I21, I28, J18