What appears to be ineffectiveness of educational interventions in the long run may actually be caused by statistical artefacts in the equating of tests taken at different time points or by the nature of the skill development in the absence of targeted interventions. We use longitudinal data on...

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 we show that the...