# Inference with “Difference in Differences” with a Small Number of Policy Changes

@article{Conley2011InferenceW, title={Inference with “Difference in Differences” with a Small Number of Policy Changes}, author={Timothy G. Conley and Christopher R. Taber}, journal={The Review of Economics and Statistics}, year={2011}, volume={93}, pages={113-125} }

Abstract In difference-in-differences applications, identification of the key parameter often arises from changes in policy by a small number of groups. In contrast, typical inference assumes that the number of groups changing policy is large. We present an alternative inference approach for a small (finite) number of policy changers, using information from a large sample of nonchanging groups. Treatment effect point estimators are not consistent, but we can consistently estimate their… Expand

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