Question

3. Reter 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 T3 T1, T2 T1, T3 T2, T3 T1, T2, T3 T1, T2, T3, T4 SSR 2970.64 3654.85 3584.54 5123.80 5409.79 3741.30 5409.89 5409.99 (a) For the R2 criterion, indicate which set of independent variables you would recommend as to best set for predicting y

Problem 2 is listed below:

Answer 1

1.(a) The set of independent variables which has the highest explained sum of squares or sum of squares of regression has the maximum value of R^2 as per definition of R^2, so by the method of R^2, the highest is of the set {x1, x2, x3}, but we see that it is not much different from the set {x1, x3} which means that not much impact is made by adding x32 so we chose the set {x1, x3}

2.

a) F=1803.3/0.8175=2205.87

F critical=3.10

as F> F critical

we can say regression exists between y and independent varible

d)no regressio relation exists does not mean that softwareengineer need not screen independent variable. we have to find weather interaction betwwen them exists or not.if regression equation had not existed then no need to screen independent varible.