School Entry, Educational Attainment and Quarter of Birth: A Cautionary Tale of LATE∗

We show existing studies use instruments that violate the monotonicity assumption needed for identification of a Local Average Treatment Effect (LATE) of school entry age. We propose an instrument satisfying this requirement and find no effect of entry age on the educational attainment of children born in the fourth quarter. We then estimate a model reconciling different IV estimates. We show one standard instrument is badly biased but that the other primarily captures a different LATE. We provide suggestive evidence that a waiver policy allowing some children to enter before the ‘legal’age could increase average educational attainment.