Which statement about the relationship between correlation and causation is accurate?

Which statement about the relationship between correlation and causation is accurate?

• A. It proves causation if the correlation is strong.
• B. It measures qualitative similarity between groups.
• C. It does not prove causation; correlation does not prove causation.
• D. It demonstrates causation when a third variable is ruled out.

Answer: (D)

Correlation shows whether two things tend to move together, but it does not tell you why. A strong relationship might make you think one variable causes the other, yet that pattern could also arise because both are driven by a third factor, or the connection could even be accidental or due to how the data were collected. Establishing causation requires more than just a relationship; you need temporal order (the cause comes before the effect), control of alternative explanations, and ideally evidence from experiments where you manipulate one variable and observe the effect. Ruling out a possible third variable is an important step in building a case for causation, but it does not by itself prove that one variable causes another. There can be multiple confounds, bidirectional influences, or other mechanisms at work. That’s why the accurate statement is that correlation does not prove causation.

Correlation shows whether two things tend to move together, but it does not tell you why. A strong relationship might make you think one variable causes the other, yet that pattern could also arise because both are driven by a third factor, or the connection could even be accidental or due to how the data were collected. Establishing causation requires more than just a relationship; you need temporal order (the cause comes before the effect), control of alternative explanations, and ideally evidence from experiments where you manipulate one variable and observe the effect.

Ruling out a possible third variable is an important step in building a case for causation, but it does not by itself prove that one variable causes another. There can be multiple confounds, bidirectional influences, or other mechanisms at work. That’s why the accurate statement is that correlation does not prove causation.