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,
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 for quadratic forms of interest. We find in Italian social security records that leave-out estimates of a variance decomposition in a two-way fixed effects model of wage determination to Italian social security records,