Which statement best defines correlation?

Which statement best defines correlation?

• A. The extent to which two scores vary together
• B. The rate of growth of a student's score over time
• C. The reliability of exam results across administrations
• D. The extent to which a test measures what it intends to measure

Answer: (A)

Correlation describes how two scores vary together. It asks whether changes in one measure tend to accompany changes in another. If they move in the same direction, the relationship is positive; if one goes up while the other goes down, it’s negative. This is the best way to define correlation because it focuses on the association between two variables, not on how fast a single score grows over time, how consistently a test yields similar results across administrations, or whether the test actually measures what it intends to measure. In short, correlation is about the extent two measures vary together, whereas the other concepts describe growth, reliability, or validity.

Correlation describes how two scores vary together. It asks whether changes in one measure tend to accompany changes in another. If they move in the same direction, the relationship is positive; if one goes up while the other goes down, it’s negative. This is the best way to define correlation because it focuses on the association between two variables, not on how fast a single score grows over time, how consistently a test yields similar results across administrations, or whether the test actually measures what it intends to measure. In short, correlation is about the extent two measures vary together, whereas the other concepts describe growth, reliability, or validity.