Use the data GPA1.RAW for this exercise.
(i) Add the variables mothcoll and fathcoll to the equation estimated in (7.6) and report the results in the usual form. What happens to the estimated effect of PC ownership? Is PC still statistically significant?
(ii) Test for joint significance of mothcoll and fathcoll in the equation from part (i) and be sure to report the p-value.
(iii) Add hsGPA2 to the model from part (i) and decide whether this generalization is needed.