Statistics for Business: Decision Making and Analysis, 3rd Edition

Answers for Questions, page 821

1. 1. No, coefficient of D(Rush) = − 1.29(t = − 1.32). Rushed jobs are cheaper because they lack detailing (which increases costs).

2. 3. No, due to collinearities. The backward process produces the same model.

3. 5. R² = 0.380, adjusted R² = 0.301, s_e = 1.89

   1. So many non−significant effects and collinearities

   2. To within ±2(1.89) were there no extrapolation effects.

4. 7. Bonferroni threshold shrinks to 0.05/(33 + 11) ≈ 0.00114, but same model is obtained.