← Search

Journal of Labor Economics Vol. 34 No. 2 2016

When Do Covariates Matter? And Which Ones, and How Much?

Jonah B. Gelbach

University of Pennsylvania

Abstract

Authors often add covariates to a base model sequentially either to test a particular coefficient’s “robustness” or to account for the “effects” on this coefficient of adding covariates. This is problematic, due to sequence sensitivity when added covariates are intercorrelated. Using the omitted variables bias formula, I construct a conditional decomposition that accounts for various covariates’ role in moving base regressors’ coefficients. I also provide a consistent covariance formula. I illustrate this conditional decomposition with NLSY data in an application that exhibits sequence sensitivity. Related extensions include instrumental variables, the fact that my decomposition nests the Oaxaca-Blinder decomposition, and a Hausman test result.

DOI
10.1086/683668
Volume
34
Issue
2
Pages
509-543
Language
en
Sources
openalex crossref

Cite