EXAMPLE 2.20 Suppose California Spent Half as Much?
CASE 2.1 What would happen if California spent about half of what was actually spent, say, $55 million. Figure 2.18 shows the two regression lines, with and without California. Here we see that the regression line changes substantially when California is removed. Therefore, in this setting we would conclude that California is very influential.
Figure 2.18: FIGURE 2.18 Two least-squares lines for the education spending data with the California education spending changed to $55 million, Example 2.20. The solid line is calculated using all of the data. The dashed line leaves out the data for California, which is influential here. California pulls the least-squares regression line toward it.