No. 256 · Evidence · Statistics and Probability
Clustering Illusion
Randomness is lumpier than we expect, so we see patterns where there are none.
In the Almanac
“Black 26 times”, 1913 · “Bill Miller”, 1991–2008
Both stories in full, three ways to use it and where it misleads.
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Questions
What is Clustering Illusion?
The clustering illusion is our tendency to see meaningful patterns in random data. True randomness produces streaks and clumps, and our brains rush to explain them, mistaking luck for skill or chance for cause.
How do you use Clustering Illusion?
To use it, ask whether chance alone could explain a streak, count the failures as well as the winners, and test a pattern with more data before betting on it.
When does Clustering Illusion matter?
Clustering Illusion is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Cause or coincidence?”, alongside Causal Fallacy, Confounding Factor and Correlation and Causation.
What is an example of Clustering Illusion?
Two stories show it at work: Black 26 times (1913) and Bill Miller (1991–2008). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Clustering Illusion?
Texas Sharpshooter Fallacy, Hot-Hand Fallacy and Randomness. Clustering Illusion itself comes from statistics and probability.