RESEARCH LITERACY

Correlation vs causation

Published 2026-05-18 · Last reviewed 2026-09-23 by Shariq Refai, MD, MBA, FAPA

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Educational. This page explains how to read and weigh research. It makes no claim about any treatment. How we source and review

A correlation is a statistical association between two variables. A causal claim says that changing one variable changes the other. Most cross-sectional and observational studies show correlations.

What separates a correlation from a causal claim

Demonstrating causation requires a study design that can rule out reverse causation, confounding, and selection bias.

Anxiety-specific example

Studies showing a correlation between adolescent social media use and anxiety symptoms can't, on their own, establish that social media use causes anxiety. Reverse causation, anxious teens use more social media, is a live alternative. Confounding factors such as sleep disruption and family environment are also alive. Selection effects matter too.

Designs that support causal inference

Randomized controlled trials, natural experiments, and well-instrumented causal-inference studies are the designs that most strongly support causal claims.

Why this matters for reading research on anxiety

Many anxiety headlines turn a correlation into a causal claim in a single sentence. Reading the underlying study design quickly tells you whether that move was earned.

Sources

Hill criteria for causation
https://pubmed.ncbi.nlm.nih.gov/14283879/
Date accessed: 2026-05-18

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