Which statement best differentiates correlation from causation?

• A. Correlation is a relationship; causation means one variable causes changes in the other
• B. Correlation implies causation in most cases
• C. Causation can be inferred from correlation alone
• D. Correlation always implies the same direction of change as causation

Answer: (A)

Correlation describes a relationship where two things move together, while causation means that changes in one thing actually cause changes in the other. This distinction is the key point: you can observe two variables covary without one causing the other. The statement that best differentiates them says correlation is simply a relationship, whereas causation is about one variable driving changes in the other.

That’s why the example with ice cream sales and sunburns in summer fits: they rise together, but buying ice cream doesn’t cause sunburn. There could be a common driving factor—like heat—that explains both. To conclude causation, you’d need evidence beyond just a correlation, such as the effect appearing after the cause and ruling out other explanations, typically through controlled experiments or strong study design.

So the statement is the best because it clearly separates a relationship from a directional cause-and-effect relationship, which is exactly what differentiates correlation from causation.