Right after the formula for \kappa, the following sentence reads "where ~T is the residual from a regression of all other covariates X_1i+...X_ki on T." I think it should be the other way around, " .. from a regression of T on all other covariates X_1i+...X_ki."
Right after the formula for \kappa, the following sentence reads "where ~T is the residual from a regression of all other covariates X_1i+...X_ki on T." I think it should be the other way around, " .. from a regression of T on all other covariates X_1i+...X_ki."