Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
The authors modify the basic self-sele ction model for the effects ofeducation, training, unions, and other activities on wages, by including "heterogeneity of rewards" to the activity-i.e., diffe rences across individuals in the rate of return to the activity. The authors sho w that such heterogeneity creates a new form of selectionbias. They provide tes ts for its presence and draw out its implications for the wage and welfare gains to the activity. An empirical application provides strong support for such hete rogeneityin one particular training program. Copyright 1987 by MIT Press.