Department of Economics
1285 University of Oregon
Eugene, OR 97403-1285
NBER Working Papers and Publications
|July 2014||Broken or Fixed Effects?|
with Charles E. Gibbons, Juan Carlos Suárez Serrato: w20342
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.