MSE-Optimal Difference-in-Differences Estimator

Fuente: arXiv
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Autore principale: Igarashi, Yamato
Natura: Preprint
Pubblicazione: 2026
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author Igarashi, Yamato
author_facet Igarashi, Yamato
contents This paper develops a difference-in-differences (DiD) estimation method that selects the optimal length of pre-trends by minimizing the mean squared error (MSE). Conventional DiD regression models, such as the two-way fixed effects model or the event study model, may suffer from accuracy and validity concerns. If the sample size is small, the estimator may have a larger variance. Also, pre-tests often lack power to detect violations of the parallel trends assumption as Roth (2022) highlights. By focusing on the bias and variance tradeoff, the proposed method derives the MSE-optimal estimator from the optimal length of pre-trends. Simulation results and an empirical application demonstrate the practical applicability of the proposed method.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05056
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MSE-Optimal Difference-in-Differences Estimator
Igarashi, Yamato
Econometrics
This paper develops a difference-in-differences (DiD) estimation method that selects the optimal length of pre-trends by minimizing the mean squared error (MSE). Conventional DiD regression models, such as the two-way fixed effects model or the event study model, may suffer from accuracy and validity concerns. If the sample size is small, the estimator may have a larger variance. Also, pre-tests often lack power to detect violations of the parallel trends assumption as Roth (2022) highlights. By focusing on the bias and variance tradeoff, the proposed method derives the MSE-optimal estimator from the optimal length of pre-trends. Simulation results and an empirical application demonstrate the practical applicability of the proposed method.
title MSE-Optimal Difference-in-Differences Estimator
topic Econometrics
url https://arxiv.org/abs/2605.05056