Chapter 4, Problem 4.60RE

(a)

To determine

To explain would this correlation increase, decrease or not change much if we remove the elephants.

Answer to Problem 4.60RE

Decrease.

Explanation of Solution

The correlation between the body weight for the entire data set is $r=0.86$ .

Since the actual point of elephants lies above the predicted line, the residual will be positive and thus removing this residual will decrease the correlation.

(b)

To determine

To explain would this correlation increase, decrease or not change much if we remove dolphins, hippos and humans.

Answer to Problem 4.60RE

Decrease.

Explanation of Solution

The correlation between the body weight for the entire data set is $r=0.86$ .

Points that lie above the predicted line will have a positive residual and points that lie beneath it a negative residual. The sum of the three residuals (of the three points) is then positive and removing these points will then lead to a lower correlation.