Unobservable Selection and Coefficient Stability: Theory and Evidence
扩展了关于遗漏变量偏误的理论，将偏误与系数稳定性明确联系起来，指出需同时考虑系数和R平方的变化，并提供了形式化的边界论证和验证练习，对实证研究者判断控制变量是否足以消除偏误有直接帮助。
A common approach to evaluating robustness to omitted variable bias is to observe coefficient movements after inclusion of controls. This is informative only if selection on observables is informative about selection on unobservables. Although this link is known in theory in existing literature, very few empirical articles approach this formally. I develop an extension of the theory that connects bias explicitly to coefficient stability. I show that it is necessary to take into account coefficient and <i>R</i>-squared movements. I develop a formal bounding argument. I show two validation exercises and discuss application to the economics literature. Supplementary materials for this article are available online.