Many papers use fixed effects (FE) to identify causal impacts of an intervention. In this paper we show that when the treatment status only varies within some groups, this design can induce non-random selection of groups into the identifying sample, which we term selection into identification...

We study two-way-fixed-effects regressions (TWFE) with several treatment variables. Under a parallel trends assumption, we show that the coefficient on each treatment identifies a weighted sum of that treatment's effect, with possibly negative weights, plus a weighted sum of the effects of the...

Quality of life and satisfaction with life are of particular importance for individuals as well as for society concerning the "demographic change" with now longer retirement periods. This study will contribute to the life satisfaction discussion and quantifies life satisfaction and pattern of...

Quality of life and satisfaction with life are of particular importance for individuals as well as for society concerning the "demographic change" with now longer retirement periods. This study will contribute to the life satisfaction discussion and quantifies life satisfaction and pattern of...

An interaction in a fixed effects (FE) regression is usually specified by demeaning the product term. However, this strategy does not yield a genuine within estimator. Instead, an estimator is produced that reflects unit-level differences of interacted variables whose moderators vary within...