Assignment 3

Using the NLSW88 data set, estimate the determinants of hourly wages: use grade, age, race, and married as explanatory variables. Interpret the coefficients and their statistical significance.

Diagnose the regression model: Is there any signs of heteroscedasticity? Examine the residual-versus-fitter plot, what is wrong?   

Find a way to improve the model fit without adding a new variables. But you are allowed to transform any variables already used.