Question 2.25

2.25 Strong association but no correlation

Here is a data set that illustrates an important point about correlation:

20 30 40 50 60
10 30 50 30 10
  1. Make a scatterplot of versus .
  2. Describe the relationship between and . Is it weak or strong? Is it linear?
  3. Find the correlation between and .
  4. What important point about correlation does this exercise illustrate?

2.25

(b) It is very strong but not linear; it has a curved relationship or parabola. (c) . (d) The correlation is only good for measuring the strength of a linear relationship.

corr