College Textbooks II Refer to Exercise. a. Use the values of SSR and Total SS to calculate R 2 ....

College Textbooks II Refer to Exercise.

a. Use the values of SSR and Total SS to calculate R². Compare this value with the value given in the printout.

b. Calculate R²(adj). When would it be appropriate to use this value rather than R² to assess the fit of the model?

c. The value of R²(adj) was 95.7% when a simple linear model was fit to the data. Does the linear or the quadratic model fit better?

Exercise:

College Textbooks A publisher of college textbooks conducted a study to relate profit per text y to cost of sales x over a 6-year period when its sales force (and sales costs) were growing rapidly. These inflation-adjusted data (in thousands of dollars) were collected:

Profit per Text, y	16.5	22.4	24.9	28.8	31.5	35.8
Sales Cost per Text x	5.0	5.6	6.1	6.8	7.4	8.6