Refer to Problem 14. Using the computer output for that problem, and the accompanying output here, answer the following questions.
a. Determine the variance inflation factors for the estimated model in part (b) of Problem 14. Does collinearity appear to be a problem?
b. Determine the estimated equation of the quadratic regression of the number of customers applying for the discount (Y) on the centered discount level (Z).
c. Determine the variance inflation factors for the estimated model in part (b) of this problem. Does collinearity appear to be a problem?
d. Conduct variables-added-in-order tests for the model in part (b).
e. Carry out tests for the significance of the quadratic regression in part (b) and for the adequacy of fit of the second-order model.
f. Based on the results from Problem 14 and parts (a) through (e) of this problem, which of the two regressions appears to be more appropriate for predicting the number of customers who apply for the discount?