A simple linear regression analysis based on a data set that consists of 20 observations yielded the following estimated equation:
Q = 120 - 3.6P
If the coefficient of determination is 0.81, then the correlation coefficient is equal to
A) 0.81.
B) -0.81.
C) -0.90.
D) 0.90.

Question

Quizplus · Accepted Answer

The coefficient of determination (R²) is 0.81, which means the correlation coefficient (r) is the square root of R². Since the slope of the regression equation is negative (-3.6), the correlation coefficient is also negative. Thus, r = -√0.81 = -0.90.

A Simple Linear Regression Analysis Based on a Data Set