EXAMPLE 10.25

Correlation test using a calculator. The correlation between BMI and PA is r = −0.385. Recall that n = 100. The t statistic for testing the null hypothesis that the population correlation is zero is

= −4.13

The degrees of freedom are n − 2 = 98. From Table D, we conclude that P < 0.0001. This agrees with the Minitab output in Figure 10.17, where the P-value is given as 0.000. The data provide clear evidence that BMI and PA are related.