Diff-in-Diff

Owing to the steadily increasing popularity of Diff-in-Diff models across an array of fields, including law, Stata's newest version (v.17) builds out its Diff-in-Diff modeling capacities (a brief summary tutorial video is here). While Stata's brief video provides a quick introduction, Brady Neal's more detailed Diff-in-Diff modeling video (here) might assist those seeking more comprehensive information. Obviously, Diff-in-Diff models are not without important limitations, including the all-important parallel trends assumption. That such modeling limitations exist, however, do not distinguish Diff-in-Diff specifications from other competing empirical strategies.