x y

0 0 1 1 -1 1 2 4 -2 4

Notice that the y-value of each point is the square of its x- value. Thus the y-value of a point is completely determined by its x-value. If correlation measured association in general, the correlation coefficient of this scatter diagram would have to reflect this perfect association. It would have to have a value of -1 or 1. Instead, the value of the correlation coefficient is equal to

a. -0.5

b. 0

c. 0.5

d. -0.75 e. 0.75