A wide literature uses date of birth as an instrument to study the causal effects of educational attainment. This paper shows how parents delaying their children’s initial enrollment in kindergarten, a practice known as redshirting, can make estimates obtained through this identification...

This paper studies causal effects informative for deciding the age when children should start kindergarten. I present evidence from the Early Childhood Longitudinal Study, Kindergarten Class of 1998–99 (ECLS-K) that standard instrumental variable strategies do not identify effects of delaying...