The materials in this repo include sample Stata code and data that implements several heterogeneity-robust difference-in-difference (DD) estimators that are related to recent literature on staggered DD, or DD designs where treatment does not happen for all units at the same time. Relevant articles for these materials and the related DD literature include:

1. Callaway, B., & Sant’Anna, P. H. (2021). Difference-in-differences with multiple time periods. Journal of Econometrics, 225(2), 200-230.
2. Chin, M. J. (2023). School district consolidation in North Carolina: Impacts on school composition and finance, crime outcomes, and educational attainment. Economics of Education Review, 95, 102432.
3. Gardner, J. (2022). Two-stage differences in differences. arXiv preprint arXiv:2207.05943.