Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This paper considers the use of instrumental variables to identify a correlated random coefficients model in which coefficients are correlated with (or stochastically dependent on) the regressors. A correlated random coefficients model is central to the human capital earnings model. Conditions are given under which instrumental variables identify the average rate of return. These conditions are applied to David Card's version of Gary Becker's Woytinsky lecture.