13.17 Softball data For the Softball data set on the book’s website, for each game, the variables are a team’s number of runs scored (RUNS), number of hits (HIT), number of errors (ERR), and the difference (DIFF) between the number of runs scored by that team and by the other team, which is the response variable. MINITAB reports Difference = −4.03 + 0.0260 Hits

+ 1.04 Run − 1.22 Errors

a. If you know the team’s number of runs and number of errors in a game, explain why it does not help much to know how many hits the team has.

b. Explain why the result in part a is also suggested by knowing that R2 = 0.7594 for this model, whereas R2 = 0.7593 when only runs and errors are the explanatory variables in the model.