The expression anecdotal evidence refers to evidence from anecdotes. In cases where small numbers of anecdotes are presented, there is a larger chance that they may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases. Anecdotal evidence is considered dubious support of a generalized claim; it is, however, within the scope of scientific method for claims regarding particular instances. Anecdotal evidence is no more than a type description (i.e., short narrative), and is often confused in discussions with its weight, or other considerations, as to the purpose(s) for which it is used. This is true regardless of the veracity of individual claims
“Debunking PseudoSkeptical Arguments of Paranormal Debunkers” by Winston Wu. His article makes several interesting arguments that should be considered.
The “anecdotal evidence is invalid” argument is perhaps the one most often used by skeptics, and also the core philosophical difference between believers and skeptics. In fact, this issue is often the impasse point that the debates between believers and skeptics reach. The term “anecdote” technically refers to an unpublished story or personal testimony. But in this case, it refers to any eyewitness account or claim of a paranormal nature without hard evidence to corroborate it.
This classification is one of the main categories that skeptics put paranormal evidence into in order to dismiss it. (Another category being the “unreplicable / uncontrolled” group that scientific experiments supporting psi are often put into. See Argument # 17 and Argument # 18) Skeptics who use this argument often claim that the evidence we have for paranormal claims is largely anecdotal and therefore worthless as scientific evidence. They also claim that anecdotal evidence is invalid because it is largely untestable and subject to error. Some skeptics will even go so far as to say that anecdotal evidence is zero evidence. Not surprisingly though, skeptics tend to quote anecdotal evidence when it supports their side! (another double standard) Therefore it appears that classifying evidence as “anecdotal” is simply a dimissal tactic to try to discredit evidence that skeptics can’t explain away.
To read more, click on the link below.