The ANOV table given in Table 9.29 resulted from fitting the multiple regression model ???? = ????0+????1????1+⋯+????9????9+????, and the ANOV table in Table 9.30 resulted from fitting the reduced model that excluded the explanatory variables ????6,????7,????8, and ????9.

Use the information in Tables 9.29 and 9.30 to answer the following questions.

(a) Test ????0 ∶ ????6 = ????7 = ????8 = ????9 = 0 at the ???? = 0.05 level.

(b) Do the explanatory variables ????6,????7,????8, and ????9 appear to be important in the model for ????? Explain.

(c) Compute the value of BIC for both models and use the difference of the BIC value to determine which model is better.