Many instrumental variable (IV) regressions include control variables to justify (conditional) independence of the instrument and the potential outcomes. The plausibility of conditional IV independence crucially depends on the timing when the control variables are determined. This paper...

Does universal preschool constitute an effective policy tool to promote the development and integration of children from minority groups? In the light of rising cross border migration and increasing ethnic variation in many developed countries, we address this question for the children of the...