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TRAP #013 ·VOL I The Individual · Judgment & Evaluation ErrorsLEXICON ENTRY

Clustering Illusion

We see patterns and streaks in random data because our brains cannot tolerate genuine randomness.
Category: BiasEvidence: ReplicatedTier 1Type: Mechanismⓘ what these mean

This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.

When it shows up

Sports commentary ("hot hand" debates), financial chart reading, cancer cluster investigations, gambling behaviour. A random sequence of coin flips will contain streaks that look meaningful. Bombing patterns in WWII London appeared clustered but matched random distribution exactly.

Failure mode

Developing elaborate theories to explain noise. Trading strategies built on spurious chart patterns. Public health scares from random geographic clustering. Policy interventions targeting phantom patterns.

Countermeasure

Before concluding a pattern is real, ask: "What would genuine randomness look like in this dataset?" Run the statistical test. Most apparent patterns in small samples are noise. Apply CL-2 (Base Rate Check).

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Related traps

Also connected in the mapThe Narrative Fallacy·10 more, locked

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Want the full correction for Clustering Illusion?

This entry has the mechanism and countermeasure. The full write-up - real cases, sources, the audit prompt - comes later.

Entry #13 of 631 in The Lexicon · see the full Lexicon