Which of the following is true about correlation?

• A. They measure variance
• B. They measure both direction and strength of correlation
• C. They measure causation
• D. They measure only the direction

Answer: (B)

Correlation quantifies the relationship between two variables by indicating direction and strength. The correlation coefficient ranges from -1 to 1: a positive value means the variables tend to move together, a negative value means they move in opposite directions. The magnitude tells how strong that linear relationship is—the closer to 1 or -1, the stronger the association; near 0 indicates a weak linear relationship. This is why the statement about correlation being able to measure both direction and strength is correct. It doesn’t measure variance, which describes how spread out a single variable is, and it doesn’t imply causation—two variables can be correlated without one causing the other. It also mainly reflects linear relationships; non-linear patterns may not show up strongly in the correlation, even if a relationship exists.