EXAMPLE 2.19 Is California Influential?
CASE 2.1 To answer this question, we compare the regression lines with and without California. The result is in Figure 2.17. The two lines are very close, so we conclude that California is not influential with respect to the least-squares slope and intercept.
Figure 2.17: FIGURE 2.17 Two least-squares lines for the education spending data, Example 2.19. The solid line is calculated using all of the data. The dashed line leaves out the data for California. The two lines are very similar, so we conclude that California is not influential.