Causal Inference in Education Research Seminar (CIERS): How are Students Selected into and Affected by Late Entry into Kindergarten? Looking Beyond the LATE.

Abstract:
Social, policy, academic, and media venues are alight with controversy over when children should enter kindergarten. Delaying entry (also called late entry or “academic redshirting”) is especially contentious because privileged parents may delay their children in an attempt to give them a competitive edge. Redshirted students do outperform their peers on average, but if there is enough positive selection, the causal effect of late entry could be small. Assuming a homogenous treatment effect, one could compare OLS estimates of the gains from older entry to IV estimates obtained using the cutoff instrument. Doing this would suggest that positive selection into late entry accounts for 23% of the OLS-estimated gains. Assuming treatment effect homogeneity, however, makes observed entry behavior rationalizable only by preferences. By allowing for treatment effect heterogeneity, I make two new findings: (1) students actually select negatively into late kindergarten entry (had they entered on time they would have performed worse in third grade than other on time entrants), and (2) older entry boosts the average late entrant’s third grade math scores by at least 0.42 SD (the gain to late entrants is at least double the gain to on time entrants). These findings suggest that, on average, parental redshirting decisions improve their child’s performance—at least in the short term. They also help resolve the puzzle of motivations for late entry: privileged families are more able to pay the cost but only do so if they think their child may not be “ready” for kindergarten.