# Correlation implies causation

*Also called: Cum hoc ergo propter hoc*

- **Cluster:** Causal errors — Sequence, coincidence and hindsight read as cause
- **Page:** https://fallacy.wiki/fallacy/correlation-causation/
- **In Arabic:** https://fallacy.wiki/ar/fallacy/correlation-causation.md
- **Licence:** CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

## What it is

Reading a statistical association as proof that one variable drives the other.

## In the wild

> Ice cream sales track drownings, so ice cream drowns people.

## How to answer it

Look for a third factor that could produce both, and check whether the direction could be reversed.

## Origin and naming

Often given in Latin as 'cum hoc ergo propter hoc', 'with this, therefore because of this'. The warning that correlation is not causation became a fixture of statistics teaching in the twentieth century, alongside famous spurious pairings like ice cream sales and drownings, both driven by hot weather.

## More places it shows up

- Schools with more music programs get better test scores, so music must be raising the scores — not the neighborhoods that fund both.
- Countries that eat the most chocolate win the most Nobel prizes, so chocolate makes you smarter.
- Our most engaged users are also our highest payers, so let's make everyone more engaged and revenue will follow.
- Cities with more police have more crime, so adding police clearly causes crime.

## How to spot it

- The whole case is 'these two numbers move together' — no experiment, no mechanism, no third variable ruled out.
- The arrow only ever points one direction; nobody checks whether Y might be causing X instead.
- The claim survives exactly as long as nobody asks what else the two things share.

## Nearby

- [Post hoc ergo propter hoc](https://fallacy.wiki/fallacy/post-hoc.md)
- [Fallacy of the single cause](https://fallacy.wiki/fallacy/single-cause.md)
- [Texas sharpshooter](https://fallacy.wiki/fallacy/texas-sharpshooter.md)

## Read more

- [Wikipedia](https://en.wikipedia.org/wiki/Correlation_does_not_imply_causation)

---

From fallacy.wiki — a bilingual field guide to 91 logical fallacies, published by phi holdings. Licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/): reuse freely with attribution to fallacy.wiki.