Difference-in-Differences Estimators of Intertemporal Treatment Effects

Clément de Chaisemartin (1) , Xavier d'Haultfoeuille (2)

1 ECON - Département d'économie (Sciences Po)
2 CREST - Centre de Recherche en Économie et Statistique

We study treatment-effect estimation, with a panel where groups may experience multiple changes of their treatment dose. We make parallel trends assumptions, but do not restrict treatment effect heterogeneity, unlike the linear regressions that have been used in such designs. We extend the event-study approach for binary-and-staggered treatments, by redefining the event as the first time a group's treatment changes. This yields an eventstudy graph, with reduced-form estimates of the effect of having been exposed to a weakly higher amount of treatment for ℓ periods. We show that the reduced-form estimates can be combined into an economically interpretable cost-benefit ratio.

Keywords: Differences-in-differences; Dynamic treatment effects; Heterogeneous treatment effects; Event-study graph; Parallel trends; Panel data; Policy evaluation; Cost-benefit analysis

Domains: Humanities and Social Sciences; Economics and Finance

Clément de Chaisemartin, Xavier d'Haultfoeuille. Difference-in-Differences Estimators of Intertemporal Treatment Effects. 2022. ⟨hal-03873903⟩