What is the anecdotal fallacy?

Brushing aside solid statistical evidence in favour of a vivid personal story or isolated example.

A single striking case (or a "my uncle did X and was fine" anecdote) is treated as outweighing a large body of data. It fails because one dramatic instance isn't representative — vivid cases stick in the mind far better than dull statistics, but memorability isn't probability. (LaBossiere calls the dramatic-event version misleading vividness.)

"Sure, the data says seatbelts save lives, but my cousin survived a crash because he was thrown clear of the car — so I don't bother with mine."

One survivor doesn't overturn the aggregate statistics showing belts reduce death across millions of crashes. The plural of "anecdote" is not "data."

Tip: When a gripping story collides with broad statistics, the statistics usually describe what's likely; the anecdote describes what's memorable.