From time to time, I get curious about some issues broadly related to econometrics and the work that I do. When that happens, I usually end up writing something about it for the sake of my own understanding.
With the hope that these writings may help other people, I’ve decided to post them here from time to time.
Published: January 2, 2021
Since I have started working on Difference-in-Differences methods with variation in treatment timing, I routinely get asked: What are the problems with event-study estimates based on two-way-fixed effects (TWFE) linear regressions? In this post, I revisit this question via a simple and hopefully easy-to-understand simulation exercise. All in all, I show that TWFE is, in general, not the same as Difference-in-Differences, but you may have heard me saying this 1,000,000 times by now.
Published: May 29, 2020
Recently, Correia, Luck and Verner (2020) put forward a very interesting paper that, among other things, analyze whether Non Pharmaceutical Interventions helped mitigate the adverse economic effects of the 1918 Spanish Flu pandemic on economic growth. They find suggestive evidence that NPIs may mitigate the adverse economic consequences of a pandemic. Lilley, Lilley and Rinaldi (2020), on the other hand, cast some doubts about the "robustness" of the findings reported by Correia, Luck and Verner (2020). In this post, I revisit this debate, making use of some of the difference-in-differences procedures that I have been working on.