Question

Given the least squares regression line = -2.88 + 1.77x, and a coefficient of determination of 0.81, the coefficient of correlation is:

A) -0.88
B) +0.88
C) +0.90
D) –0.90

I picked C +0.90

Answer 1

If you take the square root of 0.81, you have two possibilities, which are +0.90 or -0.90. You chose the correct one. Do you know why? The correlation coefficient takes the same sign as the slope. If b is positive (regression line = a + bx), use the positive root. If b is negative, then use the negative root.

I hope this helps.

Answer 2

b