Regional Policy Evaluation: Interactive Fixed Effects and Synthetic Controls
对比了交互固定效应、双重差分和合成控制法在区域政策评估中的表现，发现双重差分存在普遍偏误，并通过蒙特卡洛实验和法国企业区政策案例验证了方法优劣。
In this paper, we investigate the use of interactive effect or linear factor models in regional policy evaluation. We contrast treatment effect estimates obtained using Bai (2009) with those obtained using difference in differences and synthetic controls (Abadie and coauthors). We show that difference in differences are generically biased, and we derive support conditions for synthetic controls. We construct Monte Carlo experiments to compare these estimation methods in small samples. As an empirical illustration, we provide an evaluation of the impact on local unemployment of an enterprise zone policy implemented in France in the 1990s.