Earnings and more A second predictor in Exercise 13 improved the regression model of Exercise 1, so let’s try a third. Here’s a model with average ACT score of the entering class included:

Response variable is: Earn R squared = 36.5%

s = 5372 with 687 - 4 = 683 degrees of freedom Variable Coefficient SE(Coeff) t-ratio P-value Intercept 25162.8 2340 10.8 60.0001 SAT 10.1117 4.355 2.32 0.0205

%need -8564.03 1320 -6.49 60.0001 ACT 551.243 170.0 3.24 0.0012

a) The coefficient of SAT in this model is quite different from the SAT coefficient in the original model of Exercise 1 or the multiple regression model of Exercise