Randomized experiments provide policy relevant treatment effects if there are no spillovers between participants and nonparticipants. We show that this assumption is violated for a Danish activation program for unemployed workers. Using a difference-in-difference model e show that the...

This paper reports about a randomized field experiment in which first year economics and business students at the University of Amsterdam could earn financial rewards for passing the first year requirements within one year. Participants were assigned to a high, low and zero (control) reward...