In this paper we report the results of randomized trials designed to measure whether stricter
enforcement and verification of work search behavior alone decreases unemployment insurance (Ul)
claims and benefits. These experiments were designed to explicitly test claims based on
nonexperimental data, that a prime cause of overpayment is the failure of claimants to actively seek
work. Our results provide no support for the view that the failure to actively search for work has been a
cause of overpayment in the UI system.

This paper quantities the extent to which the rise in the measured
return to education between I979 and 2000 is reflecting a change in the
causal effect of education on labor market eamings. The conceptual issues
are formalized in a two-factor model of ability. schooling and eamings that
allows heterogeneity in absolute and comparative advantage across the
population. ln particular, the framework implies that a rise in the true return
to education will increase the degree of convexity of the relationship
between eamings and years of education for a fixed cohort of individuals.
Permanent differences in the levels of the eamings-schooling relationship
across cohorts will arise if the mapping between schooling and ability differs
across cohorts. These implications of the two-factor model allow the
identification of changes in the causal effect of education over time and
across cohorts.