Figure 13.28(a) gives the residuals from the simple linear regression model describing the service time data in Exercise 13.5.
a. In this exercise we construct a normal plot of the residuals from the simple linear regression model. To construct this plot, we must first arrange the residuals in order from smallest to largest. These ordered residuals are given in Table 13.3 on the next page. Denoting the ith ordered residual as e(i) (i = 1.2,..., 11), we next compute for each value of i the point z(i). These computations are summarized in Table 13.3. Show how z(4) = .46 and z(10) = 1.05 have been obtained.
TABLE 13.3
Ordered Residuals and Normal Plot Calculations for Exercise 13.62(a)

b. The ordered residuals (the e(i)'s) are plotted against the z(i)'s in Figure 13.29. Does this figure indicate a violation of the normality assumption?
FIGURE 13.29
Normal Plot of the Residuals for Exercise 13.62(b)

6526 50742 26256 24705 +80358025792 8 7531 0864 10876 33012 34556789 sid 9 1 3 7 9591533 rp 65320002357 OR 1 2 3 4 5 6 7 8 9 0 1 10.0 8.0 6.0 4.0 2.0 0.0 2.0 4.0 -6.0 8.0 2.0 1.5 -1.0 0500 05 0 15 2.0 Normal Score