Linear panel models, and the "event-study plots" that often accompany them, are popular tools for learning about policy effects. We discuss the construction of event-study plots and suggest ways to make them more informative. We examine the economic content of different possible identifying...

In the programming period 2007-2013, the European Structural and Investment Fund (ESIF) invested €237 million in Slovak hospitals. We investigate whether this injection of additional funds has improved the quality of healthcare in the targeted hospitals. As a measure of quality, we use the...

Linear regressions with period and group fixed effects are widely used to estimate policies' effects: 26 of the 100 most cited papers published by the American Economic Review from 2015 to 2019 estimate such regressions. It has recently been show that those regressions may produce misleading...

Group-based incentive pay is attractive in contexts where production is complex and interdependent, yet freeriding is a paramount concern. We assess the introduction of group-based performance pay in a modern industrial production setting using difference-in-difference estimation. Performance...

We study regressions with period and group fixed effects and several treatment variables. Under a parallel trends assumption, the coefficient on each treatment identifies the sum of two terms. The first term is a weighted sum of the effect of that treatment in each group and period, with weights...