Question

Which of the following statements is true?

A. The correlation coefficient equals the proportion of times two variables lie on a straight line.
B. The correlation coefficient will be +1.0 only if all the data lie on a perfectly horizontal straight line.
C. The correlation coefficient measures the fraction of outliers that appear in a scatterplot.
D. The correlation coefficient is a unitless number and must always lie between –1.0 and +1.0, inclusive.

Answer 1

A. That doesn't mean anything.
B. I hope not. We need to use it for other lines.
C. What? It can be negative! What fraction is that?
D. That's better.