Anecdote
Etymology
From Greek "anekdota" (things unpublished), from "an-" (not) and "ekdotos" (given out, published). The Byzantine historian Procopius titled his private, scandalous memoir the "Anecdota" — the stuff not fit for publication — and the word came to mean the juicy, off-the-record tale.
noun · /AN-ik-doht/
A short, entertaining account of a real incident or person.
What it names
The small true story — vivid and memorable — whose very vividness makes it a treacherous basis for general claims.
Example
He answered the statistics with an anecdote about his uncle, as if one healthy smoker settled the question.
Related idea
An anecdote is a single vivid case; something anecdotal is evidence made only of such cases — persuasive to hear, but no substitute for systematic data.