1. Looking carefully at the stepwise regression model, you can see that the value of the slope coefficient for variable x2, family income, changes as a new variable is added to the regression model. Discuss why this change takes place.
2. Analyze the stepwise regression model. Write a report to the marketing manager pointing out the strengths and weaknesses of the model. Be sure to comment on the department's goal of being able to use the model to predict which customers will purchase high volumes from McCracken.
3. Plot the residuals against the predicted value of y and comment on what this plot means relative to the aptness of the model.
a. Compute the standardized residuals and form these in a frequency histogram. What does this indicate about the normality assumption?
b. Comment on the overall aptness of this model and indicate what might be done to improve the model.