9.4 - Problems with Difference-in-Differences

In this part of the Introduction to Causal Inference course, we cover some important problems with the difference-in-differences method for causal effect estimation. Please post questions in the YouTube comments section. Introduction to Causal Inference Course Website: causalcourse.com Course Lectures Playlist: https://www.youtube.com/watch?v=JNQy9v_nVxc&list=PLoazKTcS0Rzb6bb9L508cyJ1z-U9iWkA0&index=61