The clustering illusion is the tendency to see patterns and meaningful clusters in random data — to perceive order where only chance exists.

The Basketball Example

The "hot hand" in basketball — the belief that a player who has hit several shots in a row is more likely to hit the next one — was long accepted as obvious. Statistical analysis has repeatedly failed to confirm it. The streaks we see are consistent with random variation.

Why the Brain Does This

Pattern recognition is one of the brain's core competencies — and for good evolutionary reason. In most natural environments, clusters mean something. Seeing predator tracks twice in the same area is a meaningful signal. Randomness is a modern concept that the brain isn't wired to recognize naturally.

Real Damage

• Trading systems built on patterns in random price data
• Superstitions formed from coincidental sequences
• Medical treatments adopted because of random improvement clusters
• Sports strategy distorted by streak narratives

Reference:

Wikipedia: Clustering Illusion

https://en.wikipedia.org/wiki/Clustering_illusion