Evidence quality
Correlation
A relationship where two variables tend to change together.
What it means
Definition
Correlation. Correlation describes a pattern, not a proven cause. The relationship may reflect causation, reverse causation, confounding or coincidence.
What it can tell you
It can help separate an observed association from a tested causal claim.
What it cannot tell you
It cannot remove confounding or prove causation without stronger study design and analysis.
Headline trap
Why this matters in headlines
Ice cream sales and sunburn correlate in summer, but ice cream does not cause sunburn.