=+31. Unusual points. Each of the four scatterplots a–d that follow shows a cluster of points and one “stray” point. For each, answer questions 1–4:

1) In what way is the point unusual? Does it have high leverage, a large residual, or both?

2) Do you think that point is an influential point?

3) If that point were removed from the data, would the correlation become stronger or weaker? Explain.

4) If that point were removed from the data, would the slope of the regression line increase, decrease, or remain the same? Explain.

a) b)

c) d)

M16_SHAR8696_03_SE_C16.indd 574 14/07/14 7:38 AM Exercises 575