A sam ple o f 25 observations provides th e follow ing statistics:

sx = 2 , sy = 5, and sxy = − 1.75

a. Calculate and in terpret th e sam ple correlation coefficient rxy.

b. Specify th e co m p etin g hypotheses in order to d eterm in e w h eth er th e po pulation correlation coefficient differs from zero.

c. M a ke a conclusion a t th e 5 % significance level. P-69 A p p l i c a t i o n s