Staggered Difference-in-Differences in Gravity Settings: Revisiting the Effects of Trade Agreements
将交错双重差分的扩展双向固定效应估计量嵌套入结构引力模型，发现现有文献可能低估区域贸易协定的效应（样本中低估超50%），方法可推广至移民和外国直接投资研究。
We nest an extended two-way fixed effect (ETWFE) estimator for staggered difference-in-differences within the structural gravity model. To test the ETWFE, we estimate the effects of regional trade agreements (RTAs). The results suggest that RTA estimates in the current gravity literature may be biased downward (by more than 50 percent in our sample). Sensitivity analyses confirm the robustness of our main findings and demonstrate the applicability of our methods across settings. We expect the ETWFE methods to have significant implications for estimates of other policy variables in the trade literature and for gravity regressions on migration and foreign direct investment.