# Texas sharpshooter

*Also called: Clustering illusion, post hoc pattern fitting*

- **Cluster:** Evidence and sampling — The data that was gathered, and the data that was not
- **Page:** https://fallacy.wiki/fallacy/texas-sharpshooter/
- **In Arabic:** https://fallacy.wiki/ar/fallacy/texas-sharpshooter.md
- **Licence:** CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

## What it is

Drawing the target around the hits, so a pattern is defined after the data is seen.

## In the wild

> The prediction hit on three of forty forecasts, so it is accurate.

## How to answer it

Ask whether the pattern was specified before the data was collected.

## Origin and naming

Named for a tall tale about a marksman who fires into the side of a barn, then paints a bullseye around the tightest cluster of holes. The image goes back to John Venn's 1866 Logic of Chance, and the Texas version surfaced in statistical writing in 1977 before Atul Gawande popularized it in 1999. It is the statistical face of apophenia — pattern-seeking after the fact.

## More places it shows up

- A newsletter subscriber counts back through an astrologer's fifty weekly forecasts and reports only the three that 'came true'.
- An analyst tracks which of his hundred stock picks beat the market and publishes a report titled 'My Seven Proven Winners'.
- A city's crime map shows a cluster of incidents in one district and the evening news declares a 'crime corridor' — on data from a single quarter.
- A sports bettor posts screenshots of his last three wins and calls himself a sure-thing tipster; the full ledger is private.

## How to spot it

- The criterion of success is defined after the results are in — no one wrote down the prediction beforehand.
- The denominator is missing: 'three hits' is reported, 'out of how many' is not.
- The 'pattern' is always drawn around the data that exists, never where the data was supposed to land.

## Nearby

- [Cherry picking](https://fallacy.wiki/fallacy/cherry-picking.md)
- [Correlation implies causation](https://fallacy.wiki/fallacy/correlation-causation.md)
- [Conjunction fallacy](https://fallacy.wiki/fallacy/conjunction.md)
- [Hindsight bias](https://fallacy.wiki/fallacy/hindsight.md)

## Read more

- [Wikipedia](https://en.wikipedia.org/wiki/Texas_sharpshooter_fallacy)
- [The Fallacy Files](https://www.fallacyfiles.org/texsharp.html)

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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.