2018/04/30 by Zhuan Pei, Jörn‐Steffen Pischke, Jörn-Steffen Pischke +1 · 2 citations
Mathematics · Social Sciences · #Advanced Causal Inference Techniques #School Choice and Performance #Statistical Methods and Inference
paper · pdf · doi:10.1080/07350015.2018.1462710
openalex publication_date 2018/04/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Researchers frequently test identifying assumptions in regression-based research designs (which include instrumental variables or difference-in-differences models) by adding additional control variables on the right-hand side of the regression. If such additions do not affect the coefficient of interest (much), a study is presumed to be reliable. We caution that such invariance may result from the fact that the observed variables used in such robustness checks are often poor measures of the potential underlying confounders. In this case, a more powerful test of the identifying assumption is to put the variable on the left-hand side of the candidate regression. We provide derivations for the estimators and test statistics involved, as well as power calculations, which can help applied researchers interpret their findings. We illustrate these results in the context of estimating the returns to schooling.