Anecdotal evidence is an informal account of evidence in the form of an anecdote. The term is often used in contrast to scientific evidence, as evidence that cannot be investigated using the scientific method.
The problem with arguing based on anecdotal evidence is that anecdotal evidence is not necessarily typical; only statistical evidence can determine how typical something is. Misuse of anecdotal evidence is an informal fallacy. When used in advertising or promotion of a product, service, or idea, anecdotal evidence is often called a testimonial and is banned in some jurisdictions.
The term is also sometimes used in a legal context to describe certain kinds of testimony. Psychologists have found that people are more likely to remember notable examples than the typical example.