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

The correct answer is:

a set of four data pairs with a correlation coefficient r = –0.8

Explanation:

The correlation coefficient, or r value, tells us how well the regression model fits the data.  The r values range from -1 to 1, with -1 being a perfect fit of a negative trend and 1 being a perfect fit of a positive trend.  The closer the r value is to -1 or 1, the better the line fits; the closer the r value is to 0, the worse the fit.

Since the r value is -0.8, which is very close to 1 (think 80%), this means this would be a good candidate for linear regression.

47 - 90 = 43

43 - 180 = x

x = 137