Correlation vs. causation: third variables
A study finds that people who carry lighters are more likely to develop lung cancer. The most likely explanation is that:
Answer C: explanation for every choice
A
Correlation alone cannot show that one variable causes the other.
B
Reverse causation does not fit: the cancer does not lead people to carry lighters.
C
Correct. Smoking leads people to carry lighters and causes lung cancer, producing a correlation without a causal link between the two.
D
Nothing suggests an error. The correlation is real but explained by a confound.
TakeawayCorrelation can reflect a confounding third variable.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID ps95.