Testing for equivalence of pre-trends in Difference-in-Differences estimation

Fuente: arXiv
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Main Authors: Dette, Holger, Schumann, Martin
Format: Preprint
Published: 2023
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author Dette, Holger
Schumann, Martin
author_facet Dette, Holger
Schumann, Martin
contents The plausibility of the ``parallel trends assumption'' in Difference-in-Differences estimation is usually assessed by a test of the null hypothesis that the difference between the average outcomes of both groups is constant over time before the treatment. However, failure to reject the null hypothesis does not imply the absence of differences in time trends between both groups. We provide equivalence tests that allow researchers to find evidence in favor of the parallel trends assumption and thus increase the credibility of their treatment effect estimates. While we motivate our tests in the standard two-way fixed effects model, we discuss simple extensions to settings in which treatment adoption is staggered over time.
format Preprint
id arxiv_https___arxiv_org_abs_2310_15796
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Testing for equivalence of pre-trends in Difference-in-Differences estimation
Dette, Holger
Schumann, Martin
Econometrics
Statistics Theory
The plausibility of the ``parallel trends assumption'' in Difference-in-Differences estimation is usually assessed by a test of the null hypothesis that the difference between the average outcomes of both groups is constant over time before the treatment. However, failure to reject the null hypothesis does not imply the absence of differences in time trends between both groups. We provide equivalence tests that allow researchers to find evidence in favor of the parallel trends assumption and thus increase the credibility of their treatment effect estimates. While we motivate our tests in the standard two-way fixed effects model, we discuss simple extensions to settings in which treatment adoption is staggered over time.
title Testing for equivalence of pre-trends in Difference-in-Differences estimation
topic Econometrics
Statistics Theory
url https://arxiv.org/abs/2310.15796