Use the data from Freund (1979), presented in Problem 22 in Chapter 14. Taking the model discussed there as the maximum model, repeat parts (a) through (h) of Problem 6. In part (h), note the possible role of collinearity.
In Problem 6
a. Indicate a plausible fixed order for testing predictors, based on the nature of the data. Briefly defend your choice.
b. Use a computer program to fit the full model. Provide a test of whether or not the population multiple correlation is 0.
c. Using the fixed order, choose a best model, adding variables in a forward fashion. Do not adhere to a particular a, but use your judgment.
d. Repeat part (c) but delete the variables in the fixed order (a backward method).
e. Using a computer program employing a stepwise procedure, use a backward algorithm to find the best model.
f. Repeat part (e), using a forward algorithm.
g. Compare and contrast your conclusions for parts (c), (d), (e), and (f). Indicate your preferred model.
h. Using the ideas presented in Chapter 14, indicate how you could evaluate the adequacy of the best model and the validity of the underlying assumptions.