\"A producer of various feed additives for cattle conducts astudy of the number of days of feedlot time required to bring beefcattle to market weight. Eighteen steers of essentially identi- calage and weight are purchased and brought to a feedlot. Each steeris fed a diet with a specific combination of protein content,antibiotic concentration, and percentage of feed supplement. Thedata are as follows:

STEER  PROTEIN ANIBIO SUPPLEM TIME1    10   1    3    882    10   1    5    823    10   1    7    814    10   2    3    825    10   2    5    836    10   2    7    757    15   1    3    808    15   1    5    809    15   1    7    7510   15   2    3    7711   15   2    5    7612   15   2    7    7213   20   1    3    7914   20   1    5    7415   20   1    7    7516   20   2    3    7417   20   2    5    7018   20   2    7    69

8. Calculate the coefficient of determination and interpret.

9. Suppose x1 = PROTEIN, x2 = ANTIBIO and x3 = SUPPLEM, and youenter these predictors in the model in the order of x1, x2, x3.Find SSR(x2 | x1) and SSR(x3 | x1, x2). What do they mean?

10. Test whether adding ANTIBIO and SUPPLEM provides anyadditional predictive value, given that PROTEIN is already in themodel. Include all steps of a statistical test.