Question

For which data set is a linear regression most reasonable?
a set of nine data pairs with a correlation coefficient r = –0.4
a set of five data pairs with a correlation coefficient r = 0.3
a set of four data pairs with a correlation coefficient r = –0.8
a set of six data pairs with a correlation coefficient r = 0.6

Answer 1

The set of four data pairs with r = −0.8.

Reason: |r| = 0.8 indicates the strongest linear relationship of the four choices, so a linear model is most reasonable (though with only 4 points you should still be cautious about stability).