Here is question 2 that they are referring to....

3. Refer to problem (2). The software quality engineer decided to screen (select) the independent variables to determine the best set for predict- ing y. The regression sums of squares for some of possible regression models were found to be as follows: Independent variables in model SSR. 2970.64 3654.85 3584.54 5123.80 5409.79 3741.30 5409.89 5409.99 T2 T1,T2 (a) For the R2 criterion, indicate which set of independent variables you would recommend as to best set for predicting y (b) An observer states: "There are only four variables, so why screen? You might as well use all four." Discus