Before revision:  The estimator's limiting distribution can be represented by a linear combination of normal and non-central \chi^2 random variables . Consistent variance estimators are proposed along with a procedure for constructing uniformly valid confidence intervals . Applying a two-way fixed effects model of wage determination to Italian social security records, we find that ignoring heteroscedasticity substantially biases conclusions regarding the relative contribution of workers, firms, and worker-firm sorting to wage inequality  .
After revision:  The estimator's limiting distribution can be represented by a linear combination of normal and non-central \chi^2 random variables . Consistent variance estimators are proposed along with a procedure for constructing uniformly valid confidence intervals . Applying a two-way fixed effects model of wage determination yield substantially different conclusions regarding the relative contribution of workers, firms, and worker-firm sorting to wage inequality .