1. First Differencing 1, 2
  2. Demeaning the Data 1, 2
  3. Dummy Variables 1, 2
  4. Using xtreg 1, 2
  5. Adding Time Fixed Effects 1, 2
  6. Staggered Adoption Cohorts
  7. Modern Estimators 1, 2, 3
  8. Check That Your Code Runs
  9. Challenge 11 1, 2