Chapter 8, Problem 47E

Elephants and hippos We removed humans from the scatterplot of the Gestation data in Exercise 45 because our species was an outlier in life expectancy. The resulting scatterplot (below) shows two points that now may be of concern. The point in the upper right corner of this scatterplot is for elephants, and the other point at the far right is for hippos.

1. a) By removing one of these points, we could make the association appear to be stronger. Which point? Explain.
2. b) Would the slope of the line increase or decrease?
3. c) Should we just keep removing animals to increase the strength of the model? Explain.
4. d) If we remove elephants from the scatterplot, the slope of the regression line becomes 11.6 days per year. Do you think elephants were an influential point? Explain.