On Local Overidentification and Efficiency Gains in Modern Causal Inference and Data Combination
现代因果推断与数据整合中的局部过度识别及效率增益
This paper studies nonparametric local (over-)identification and the semiparametric efficiency in modern causal frameworks. We develop a unified approach that begins by translating structural models with latent variables into their induced statistical models of observables and then analyzes local overidentification through conditional moment restrictions. We apply this approach to three popular classes of causal models: (1) the general treatment model under unconfoundedness;…