School Entry, Educational Attainment, and Quarter of Birth: A Cautionary Tale of a Local Average Treatment Effect

Studies of the effects of school entry age on short-run and long-run outcomes generally fail to capture the parameter of policy interest and/or are inconsistent because the instrument they use violates monotonicity, required for identification of a local average treatment effect. Our instrument addresses both problems and shows no effect of entry age on the educational attainment of children born in the fourth quarter who delay enrollment only because they are constrained by the law. We provide suggestive evidence that a waiver policy allowing some children to enter before the legally permissible age increases average educational attainment.