This paper investigates the economic and empirical foundations of the evidence relating earnings to schooling quality. We replicate the Card-Krueger model for Census years 1970, 1980 and 1990 and find that it consistently produces a strong relationship between schooling quality and the rate of...

This paper examines the economic and empirical foundations of the aggregate evidence on the effect of schooling quality on earnings. A common framework is presented which nests all previous studies as special cases. We discuss two crucial identifying assumptions and test them. The first...

Semiparametric methods are developed to estimate the bias that arises from using nonexperimental comparison groups to evaluate social programs and to test the identifying assumptions that justify matching, selection models and the method of difference in differences. Using data from an...