Reconsider the patient satisfaction data in Table 4E.11. Fit a multiple regression model using both patient age

Question:

Reconsider the patient satisfaction data in Table 4E.11. Fit a multiple regression model using both patient age and severity as the regressors.
(a) Test for significance of regression.
(b) Test for the individual contribution of the two regressors. Are both regressor variables needed in the model?
(c) Has adding severity to the model improved the quality of the model fit? Explain your answer.