Why does correlation not equal causation?

Why does correlation not equal causation?

• A. Because no manipulation or control exists to prove direct cause-and-effect.
• B. Because correlation is always spurious.
• C. Because sample size determines causality.
• D. Because randomization guarantees causation.

Answer: (A)

Correlation shows that two variables tend to move together, but it does not prove that one causes the other. To establish direct cause-and-effect, you need to manipulate the cause and observe the effect while controlling for other explanations. Without this kind of manipulation or control, the observed relationship could be due to a third variable that influences both, it could be that the effect actually influences the cause (reverse causation), or it could simply be a coincidence. That’s why correlation does not imply causation. The other statements aren’t accurate. A correlation can reflect a real relationship but isn’t necessarily causal. Sample size affects precision and the power to detect an association, but it doesn’t determine whether a causal link exists. Randomization helps support causal inferences by balancing confounders, but it does not guarantee causation in all circumstances.

Correlation shows that two variables tend to move together, but it does not prove that one causes the other. To establish direct cause-and-effect, you need to manipulate the cause and observe the effect while controlling for other explanations. Without this kind of manipulation or control, the observed relationship could be due to a third variable that influences both, it could be that the effect actually influences the cause (reverse causation), or it could simply be a coincidence. That’s why correlation does not imply causation.

The other statements aren’t accurate. A correlation can reflect a real relationship but isn’t necessarily causal. Sample size affects precision and the power to detect an association, but it doesn’t determine whether a causal link exists. Randomization helps support causal inferences by balancing confounders, but it does not guarantee causation in all circumstances.