2b) (2 points) Demonstrate empirically how the coefficient on sex can be obtained in a two-step procedure involving univariate regressions. Start from the model log(wage)= Bo + Bi belavg + B2 abvavg + 8 sex +BX+ u where the other explanatory variables X are: educ, exper, expersq, union, goodhlth, black, married, south, bigcity, smllcity, and service. Show that can be obtained in a two-step regression. First step: regress sex on all other left-hand side variables: belavg, abvavg, and all other X: educ, exper, expersq, union, goodhlth, black, married, south, bigcity, smllcity, and service Report the regression model. Store the residuals from this first stage P. Report summary statistics (mean and standard deviation) for these stored residuals f. Second step: Regress log(wage) on the stored residuals P. Report the regression model. What is the coefficient on ? Did you expect that? . . 2b) (2 points) Demonstrate empirically how the coefficient on sex can be obtained in a two-step procedure involving univariate regressions. Start from the model log(wage)= Bo + Bi belavg + B2 abvavg + 8 sex +BX+ u where the other explanatory variables X are: educ, exper, expersq, union, goodhlth, black, married, south, bigcity, smllcity, and service. Show that can be obtained in a two-step regression. First step: regress sex on all other left-hand side variables: belavg, abvavg, and all other X: educ, exper, expersq, union, goodhlth, black, married, south, bigcity, smllcity, and service Report the regression model. Store the residuals from this first stage P. Report summary statistics (mean and standard deviation) for these stored residuals f. Second step: Regress log(wage) on the stored residuals P. Report the regression model. What is the coefficient on ? Did you expect that