In a study of housing demand, a county assessor is interested in developing a regression model to estimate the selling price of residential properties within her jurisdiction. She randomly selects 15 houses and records the selling price in addition to the following values: the size of the house (in hundreds of square feet), the total number of rooms in the house, the age of the house, and an indication of whether the house has an attached garage. These data are listed in the file P10_26.xlsx.
a. Use stepwise regression to decide which explanatory variables should be included in the assessor’s statistical model. Use the p-value method with a cutoff value of 0.05 for entering and leaving. Summarize your findings.
b. How do the results in part a change when the critical p-value for entering and leaving is increased to 0.10? Explain any differences between the regression equation obtained here and the one found in part a.