The applet below is designed to teach students the effect of leverage
points on a regression line. Students may add points to the plot by
clicking the mouse button. Students should note that adding points
close to the existing line barely changes the line. By adding points
far from the existing line, the regression line changes considerably.
This is particularly true for points added outside the range of the
data. This should help students understand the effect of outliers on
by R. Webster West, Dept. of Statistics, Univ. of South Carolina