The scores for two within-term examinations, X1 and X2; the current grade point average (GPA), X3; and the final exam score, Y, for 20 students in a business statistics class are listed in Table P-18.
a. Fit a multiple regression model to predict the
final exam score from the scores on the within-term exams and GPA. Is the regression significant? Explain.
b. Predict the final exam score for a student with within-term exam scores of 86 and 77 and a GPA of 3.4.
c. Compute the VIFs and examine the t statistics for checking the significance of the individual predictor variables. Is multicollinearity a problem? Explain.
d. Compute the mean leverage. Are any of the observations high leverage points?
e. Compute the standardized residuals. Identify any observation with a large standardized residual. Does the fitted model under- or overpredict the response for these observations?
SOLUTION
a. b. & c.
The regression results follow.