In addition to the value of R², another measurement used to assess the quality of a model is the sum of squares of the residuals. Recall from Section 10-2 that a residual is the difference between an observed y value and the value of y predicted from the model, which is denoted as ŷ. Better models have smaller sums of squares. Refer to the data in Table 10-7.

a. Find ∑(y - ŷ)², the sum of squares of the residuals resulting from the linear model.
b. Find the sum of squares of residuals resulting from the quadratic model.
c. Verify that according to the sum of squares criterion, the quadratic model is better than the linear model.

Table 10-7: