Explaining Birth Order Effects Using Variation in Compulsory Schooling Law

Dean R. Lillard, Cornell University
Jennifer Gerner, Cornell University

We use cross-state and temporal variation in compulsory schooling laws to explain differences across siblings in the age at school entry of children of different birth orders. The analysis takes advantage of changes in the age parents are first allowed to enroll children in public schools. Because our data, the Children of the NLSY79, cover a long time period (1986 through 2002) we observe a large number of children within families who were allowed to enter school at different ages. These differences in the age of first permitted entry means that parents face greater incentives to enter a youngest child into school at an earlier age than they did an older sibling. We use these different incentives to first control for whether parents in fact do enter children into school at different ages and then to investigate how much of sibling differences are explained by differences in age at entry.