Date of this Version
Review of Financial Studies
Controlling for unobserved heterogeneity (or “common errors”), such as industry-specific shocks, is a fundamental challenge in empirical research.This paper discusses the limitations of two approaches widely used in corporate finance and asset pricing research: demeaning the dependent variable with respect to the group (e.g., “industry-adjusting”) and adding the mean of the group's dependent variable as a control. We show that these methods produce inconsistent estimates and can distort inference. In contrast, the fixed effects estimator is consistent and should be used instead. We also explain how to estimate the fixed effects model when traditional methods are computationally infeasible.
This is a pre-copyedited, author-produced PDF of an article accepted for publication in Review of Financial Studies following peer review. The version of record is available online at: http://dx.doi.org/10.1093/rfs/hht047.
Gormley, T. A., & Matsa, D. A. (2014). Common Errors: How to (and Not to) Control for Unobserved Heterogeneity. Review of Financial Studies, 27 (2), 617-661. http://dx.doi.org/10.1093/rfs/hht047
Date Posted: 27 November 2017
This document has been peer reviewed.