Design-based Analysis in Difference-In-Differences Settings with Staggered Adoption
Abstract
In this paper we study estimation of and inference for average treatment effects in a setting with panel data. We focus on the setting where units, e.g., individuals, firms, or states, adopt the policy or treatment of interest at a particular point in time, and then remain exposed to this treatment at all times afterwards. We take a design perspective where we investigate the properties of estimators and procedures given assumptions on the assignment process. We show that under random assignment of the adoption date the standard Difference-In-Differences estimator is is an unbiased estimator of a particular weighted average causal effect. We characterize the proeperties of this estimand, and show that the standard variance estimator is conservative.
Cite
@article{arxiv.1808.05293,
title = {Design-based Analysis in Difference-In-Differences Settings with Staggered Adoption},
author = {Susan Athey and Guido Imbens},
journal= {arXiv preprint arXiv:1808.05293},
year = {2018}
}