Anecdotal Evidence refers to a body of studies which may have no proof but are useful in research efforts. It includes use of examples to support a claim though by itself it cannot provide any compelling proof in the form of statistical or scientific data. It is more of a kind of hearsay or something that is passed on by word of mouth and hence cannot be provided with evidence. Anecdotal evidence appears in various forms but the fact remains that the information is documented in an informal way which makes it difficult to test its reliability in an objective manner.
The term Anecdotal Evidence is derived form the word anecdote which indicates details of history or any unpublished narratives of interesting incidents often cited to support or illustrate a point. Anecdotal evidence provides the basis for non-expert advice which people resort to most of their times to take decisions in various routine matters. For instance whether it is to hire the services of a maid, travel agency, cabs or so on we may accept recommendations for friends or co-workers who may not have the required qualification to give expert views.
One kind of Anecdotal evidence includes giving importance to information based on somebody’s experience and hearsay rather than any proven facts. Such information may not be always untrue and often becomes the easy way out to take a decision. For example, you may be interested to have dinner in the best restaurant in your neighborhood and may accept the suggestions of friends as you do not have time to make a thorough survey of the same. Another kind of Anecdotal evidence may be true but it may not represent a typical case as the conclusion is generalized on the basis of insufficient evidence. For instance, “My father never smoked but he died of lung cancer” It is a fallacy to assume that one thing is linked to another.
In a scientific context, anecdotal evidence may refer to information that cannot be scientifically measured and validated but which may aid in pursuing research studies. It may also imply to non-scientific observations by the common man. Anecdotal evidences which are published in medical journals may be called a ‘case report’ which is open to review and as such is a more formal kind of anecdotal evidence. These reports are then subject to scientific analysis and conclusions are drawn on the basis of proven data. In scientific research, anecdotal evidence may be used as basis for a hypotheses rather than providing a proof.
Anecdotal evidence is a kind of non-scientific observation and hence considered inconclusive. Most of commercial advertisements are full of anecdotal evidences. Anecdotal evidence serves as a testimonial when used to promote a product or idea as in advertisements. For example some one may claim that a particular brand of shampoo is the best as it gives you super soft and shining hair with no side effects. You may not be provided with any scientific evidence to test the same. In fact any research or scientific analysis may prove the opposite results.