School Starting Age and Cognitive Development

Abstract

We present evidence of a positive relationship between school starting age and children's cognitive development from age 6 to 15 using a regression discontinuity design and large-scale population-level birth and school data from the state of Florida. We estimate effects of being relatively old for grade (being born in September versus August) that are remarkably stablealways just around 0.2 SD difference in test scores -across a wide range of heterogeneous groups, based on maternal education, poverty at birth, race/ethnicity, birth weight, gestational age, and school quality. While the September-August difference in kindergarten readiness is dramatically different by subgroup, by the time students take their first exams, the heterogeneity in estimated effects effectively disappears. We document substantial variation in compensatory behaviors targeted towards young for grade children. While the more affluent families tend to redshirt their children, young for grade children from less affluent families are more likely to be retained in grades prior to testing. School district practices regarding retention and redshirting are correlated with improved outcomes for the groups less likely to use those remediation approaches (i.e., retention in the case of more-affluent families and redshirting in the case of less-affluent families.) We also study college and juvenile detention outcomes using administrative data from a large Florida school district, and show that being an older age at school entry increases children's college attainment and reduces the likelihood of being incarcerated for juvenile crime.

The School-Entry-Age Rule Affects Redshirting Patterns and Resulting Disparities in Achievement

“…Another dimension of interest is whether the decision to redshirt is influenced by the academic preparation or ability of the child prior to enrollment. Two recent studies find a weak positive relationship (Bassok and Reardon 2013) and null relationship (Dhuey et al 2017).…”

“…The public interest in noncompliance with the minimum age rules stems from the wellestablished fact that other things equal, being older conveys an academic advantage, at least in elementary and middle school (Bedard and Dhuey 2006;Elder and Lubotsky 2009;Dobkin and Ferrerira 2010;Bassok and Reardon 2013;Cook and Kang, 2016;Cascio and Schanzenbach 2016;Dhuey et al 2017). For children who comply with the minimum age laws there is a oneyear spectrum of birthdays in each grade.…”

“…The older children, born just after the cut date, tend to perform better than their younger classmates, as measured by standardized test scores, likelihood of on-time promotion, and the likelihood of being identified with a learning disability (Dhuey and Lipscomb 2010;Elder 2010). Causal analysis of the effect of exact age on academic performance, using regression discontinuity or IV methods, provides a consensus on these beneficial effects, although with some disagreement about whether the effects are attenuated by middle school (Bedard and Dhuey 2006;Elder and Lubotsky 2009;Cascio and Schanzenbach 2016;Cook and Kang 2016;Dhuey et al 2017). There is every reason to believe that redshirting 1 In intercollegiate college sports, "redshirting" is used as an informal term for the practice of keeping young athletes out of competition for a year to allow them to mature physically without losing a year of NCAA eligibility.…”

“…In recent studies from state and national data sets, there is consensus that redshirting is much more common for males than females, and more common for whites than blacks or Hispanics. Several studies report that the likelihood of redshirting increases with socioeconomic status (SES) (Bassok and Reardon 2013;Dhuey et al 2017), although Dhuey and her colleagues find a countervailing pattern in Florida of retention in the primary grades that has the effect of eliminating the correlation of age with SES by third grade.…”

“…The focus on third-grade outcomes is dictated by the limitations of the dataset. The positive effects of being old for grade extend through middle school and beyond, including not only standardized test scores but also the likelihood of an exceptionality designation and involvement in criminal activity before age 16 (Cook and Kang 2016;Dhuey et al 2017). And despite this persistent advantage, old-for-grade youths are more likely to drop out before graduation (Dobkin and Ferreira 2010;Cook and Kang 2016) and then turn to serious crime (Cook and Kang 2016).…”