Difference-in-Differences Estimators of Intertemporal Treatment Effects
Econometrics
2026-05-13 v14
Abstract
We study treatment-effect estimation using panel data. The treatment may be non-binary, non-absorbing, and the outcome may be affected by treatment lags. We make a parallel-trends assumption, and propose event-study estimators of the effect of being exposed to a weakly higher treatment dose for periods. We also propose normalized estimators, that estimate a weighted average of the effects of the current treatment and its lags. We also analyze commonly-used two-way fixed-effects regressions. Unlike our estimators, they can be biased in the presence of heterogeneous treatment effects. A local-projection version of those regressions is biased even with homogeneous effects.
Cite
@article{arxiv.2007.04267,
title = {Difference-in-Differences Estimators of Intertemporal Treatment Effects},
author = {Clément de Chaisemartin and Xavier D'Haultfœuille},
journal= {arXiv preprint arXiv:2007.04267},
year = {2026}
}