Weak instrumental variables due to ignored nonlinearities in panel data: A Super Learner Control Function estimator
忽略面板非线性导致的弱工具变量:Super Learner 控制函数估计
A triangular structural panel data model with additive separable individual-specific effects is used to model the causal effect of a covariate on an outcome variable when there are unobservable confounders with some of them time-invariant. In this setup, a linear specification for the reduced-form equation might be problematic when the conditional mean of the endogenous covariate and the instrumental variables is nonlinear in the population. The reason is that ignoring the…