The article referred to in Exercise 25 presents values for the dependent and independent variables for 10 additional construction jobs. These values are presented in Tables SE26A and SE26B.

a. Using the equation constructed in part

(a) of Exercise 25, predict the concrete quantity (y) for each of these 10 jobs.

b. Denoting the predicted values by ŷ1,…, ŷ10 and the observed values by y1,… , y10, compute the quantities yi − ŷi

.

These are the prediction errors.

c. Now compute the fitted values ŷ1,…, ŷ28 from the data in Exercise 25. Using the observed values y1,…, y28 from those data, compute the residuals yi − ŷi

.

d. On the whole, which are larger, the residuals or the prediction errors? Why will this be true in general?