We show that the OLS and fixed‐effects (FE) estimators of the popular difference-in-differences model may deviate when there is time varying panel non-response. If such non-response does not affect the common-trend assumption, then OLS and FE are consistent, but OLS is more precise. However,...

This paper extends the traditional focus of active labor market policy evaluation from a static comparison of participation in a program versus nonparticipation (or participation in another program) to the evaluation of the effects of program sequences, i.e. multiple participation or timing of...