A Researcher Reports That the Correlation Between Two Quantitative Variables

Multiple Choice

A researcher reports that the correlation between two quantitative variables is r = 0.8. Which of the following statements is correct?

A) The average value of y changes by 0.8 when x is increased by 1.
B) The average value of x changes by 0.8 when y is increased by 1.
C) The explanatory variable (x) explains 0.8 or 80% of the variation in the response variable (y) .
D) The explanatory variable (x) explains (0.8) ² = 0.64 or 64% of the variation in the response variable (y) .