Broken or Fixed Effects?

Saturday, February 3, 2018
Charles E. Gibbons
Juan Carlos Suárez Serrato
Michael B. Urbancic


We replicate eight influential papers to provide empirical evidence that, in the presence of heterogeneous treatment effects, OLS with fixed effects (FE) is generally not a consistent estimator of the average treatment effect (ATE). We propose two alternative estimators that recover the ATE in the presence of group-specific heterogeneity. We document that heterogeneous treatment effects are common and the ATE is often statistically and economically different from the FE estimate. In all but one of our replications, there is statistically significant treatment effect heterogeneity and, in six, the ATEs are either economically or statistically different from the FE estimates.


Gibbons, Charles E., Juan Carlos Suárez Serrato, and Michael B. Urbancic. 2018. "Broken or Fixed Effects?". Journal of Econometric Methods, 0(0), pp. -. Retrieved Feb. 2018, from doi:10.1515/jem-2017-0002

Broken or Fixed Effects?