Texas sharpshooter
Etymology
The name comes from a joke about a Texan who fires his gun at a barn, then paints a bullseye around the tightest cluster of holes. It became a standard illustration in statistics and epidemiology for the clustering illusion. The fallacy is choosing the hypothesis to fit the data instead of testing it against fresh data.
noun phrase · /TEK-sus SHARP-shoo-ter/
Finding a pattern by cherry-picking data after the fact, then presenting it as if it were the goal all along.
What it names
Flags conclusions drawn by painting the target around wherever the hits happened to land.
Example
A company touts the three markets where its ad worked and ignores the twelve where it flopped — a Texas sharpshooter.
Related idea
It supplies the raw material for a cum hoc error by manufacturing correlations worth misreading.