9. Refer to the model for housing price selected in Example 14.1.

a) Study the studentized residuals, and show that only one is unusually large. What does this reflect?

b) Study the hat values. Which three observations have the greatest leverage. and hence the predictor values with the greatest potential to affect the fit of the regression model?

e) Study the DFFITS values. Which tree observations seem to have much more influ- ence on the fitted values than any others?

d) Study the DFBETAS for the S predictor. Which three observations have the greatest influence on the predicted partial effect of size of home"

e) Study the DFBETAS for the BA and N predictors. Are the three observations high- lighted above as influential for these predictors? Explain. 1) Refit the model without the three highly influential observations. Compare the predic- tion equation, standard errors. and R to the fit for the complete data set. Summarize the influence of this set of influenual observations