Staggered Treatment in Difference-in-Differences (The Effects, Videos on Causality, Ep 56)

Please visit https://www.theeffectbook.net to read The Effect online for free, or find links to purchase a physical copy or ebook.

The Effect is a book about research design and causal inference. How can we use data to learn about the world? How can we answer questions about whether X causes Y even if we can't run a randomized experiment? The book covers these things and plenty more. These videos are meant to accompany the book, although they can also be viewed on their own.

This video relates to material found in Chapter 18 of the book.

A version of this video without background music can be found here:    • Staggered Treatment in Difference-in-...  

All the DID stuff we've done so far has been about treatments that go into place at the same time, whether there's only one treated group or many groups all getting treated at once. But what if that's not the case? What if treatment goes into effect at different times? We used to think two-way fixed effects was fine for that. But oops! It's not. Why not, and what can we do instead?