Pre-Event Trends in the Panel Event-Study Design
Pre-Event Trends in the Panel Event-Study Design
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DOI：
10.1257/aer.20180609
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发表时间：
2019-09-01
影响因子：
10.7
通讯作者：
Shapiro, Jesse M.
中科院分区：
文献类型：
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作者：
Freyaldenhoven, Simon;Hansen, Christian;Shapiro, Jesse M.
我们考虑一种线性面板事件研究设计，其中未观察到的混淆可能与结果和感兴趣的政策变量有关。通过仅通过混杂来利用与政策相关的协变量，我们提供了识别政策因果效应的充分条件。我们的模型包含了一组参数线性的力矩方程。政策的效果可以通过2SLS来估计，即使当内生性导致结果中的事前趋势时，因果推断也是有效的。替代方法在我们的模拟中表现不佳。
We consider a linear panel event-study design in which unobserved confounds may be related both to the outcome and to the policy variable of interest. We provide sufficient conditions to identify the causal effect of the policy by exploiting covariates related to the policy only through the confounds. Our model implies a set of moment equations that are linear in parameters. The effect of the policy can be estimated by 2SLS, and causal inference is valid even when endogeneity leads to pre-event trends ("pre-trends") in the outcome. Alternative approaches perform poorly in our simulations.