Hi All, I'm working with some household level data I collected last summer, and have run into some heteroskedasticity problems. I've tried to correct for it both using White's correction and through a robust estimation technique, but neither work. I get the following errors: for Whites: Error in V %*% t(X) : non-conformable arguments for rlm: Error in rlm.default(x, y, weights, method = method, wt.method = wt.method, : x is singular: singular fits are not implemented in rlm All but one of the independent variables are dummies. Any clues on how I can either get around these errors, or correct for the heteroskedasticity in another way? andy _______________________________________________ gov1000-list mailing list gov1000-list(a)lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov1000-list