Title: Anecdotal evidence - RationalWiki
Headings: Anecdotal evidence
Anecdotal evidence
Contents
Form
Legitimate use
Problems
Regression to the mean
Adulteration
Improbability
Selection bias
Lack of follow up/incompleteness
Advantages of anecdotal evidence
The power of anecdotes
See also
External links
Notes
References

Content: If you use one or more anecdotes as an example of a general rule which is already supported by a broad, comprehensive investigation (i.e., your evidence/argument does not rely on the anecdotes, they are just used to illustrate the point). These are, by far, not the most common uses of anecdotes. Problems
“ ” If you are basing your claims on anecdotal experience, then any treatment will seem to work for anything and everything. — Steven Novella, The CAM Worldview
While anecdotes — when true, at least — are nice illustrative stories, they do not constitute evidence. This is because anecdotes only ever apply to individuals or individual experiences and are subject to the biases that this brings with it. It is impossible to say that an individual anecdote is representative and it is also impossible to actually detect the real cause of the anecdote. For instance, with life-saving medical treatments (say, pills that reduce heart-disease and subsequently lower the death rate), there are some deaths that occur whether or not the medication was taken. Therefore, if someone who is on the medication dies, you cannot tell if they would have died anyway without it — you can't prove that the medical intervention worked, or not, from the one case study. It is very rare for an intervention to be, by itself, a sufficient cause of something. Rather, they tend to change the probability of a given event occurring.