Two-Way Fixed Effects Estimators with Heterogeneous Treatment Effects

• 成果类型: Article
• 署名作者: De Chaisemartin, Clement; D'Haultfoeuille, Xavier
• 署名单位: University of California System; University of California Santa Barbara; Institut Polytechnique de Paris; ENSAE Paris
• 刊物名称: AMERICAN ECONOMIC REVIEW
• ISSN/ISSBN: 0002-8282
• DOI: 10.1257/aer.20181169
• 发表日期: 2020
• 页码: 2964-2996
• 关键词: unions; wages

摘要

Linear regressions with period and group fixed effects are widely used to estimate treatment effects. We show that they estimate weighted sums of the average treatment effects (ATE) in each group and period, with weights that may be negative. Due to the negative weights, the linear regression coefficient may for instance be negative while all the ATEs are positive. We propose another estimator that solves this issue. In the two applications we revisit, it is significantly different from the linear regression estimator.