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Anecdotal evidence

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"Anecdata" redirects here. For the web portal, see Anecdata.org.

An anecdotal evidence (or anecdata[1]) is a piece of evidence based on descriptions and reports of individual, personal experiences, or observations,[2][3] collected in a non-systematic manner.[4]

The word anecdotal constitutes a variety of forms of evidence. This word refers to personal experiences, self-reported claims,[3] or eyewitness accounts of others,[5] including those from fictional sources, making it a broad category that can lead to confusion due to its varied interpretations.

Anecdotal evidence can be true or false but is not usually subjected to the methodology of scholarly method, the scientific method, or the rules of legal, historical, academic, or intellectual rigor, meaning that there are little or no safeguards against fabrication or inaccuracy.[2] However, the use of anecdotal reports in advertising or promotion of a product, service, or idea may be considered a testimonial, which is highly regulated in some jurisdictions.[6]

The persuasiveness of anecdotal evidence compared to that of statistical evidence has been a subject of debate; some studies have argued for the presence a generalized tendency to overvalue anecdotal evidence, whereas others have emphasized the types of argument as a prerequisite or rejected the conclusion altogether.[7][8][9][10][11]

Scientific context

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See also: Scientific evidence

In science, definitions of anecdotal evidence include:

  • "casual observations/indications rather than rigorous or scientific analysis"[12]
  • "information passed along by word-of-mouth but not documented scientifically"[13]
  • "evidence that comes from an individual experience. This may be the experience of a person with an illness or the experience of a practitioner based on one or more patients outside a formal research study."[14]
  • "the report of an experience by one or more persons that is not objectively documented or an experience or outcome that occurred outside of a controlled environment"[15]

Anecdotal evidence may be considered within the scope of scientific method as some anecdotal evidence can be both empirical and verifiable, e.g. in the use of case studies in medicine. Other anecdotal evidence, however, does not qualify as scientific evidence, because its nature prevents it from being investigated by the scientific method, for instance, in that of folklore or in the case of intentionally fictional anecdotes. Where only one or a few anecdotes are presented, there is a chance that they may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases.[16][17] Similarly, psychologists have found that due to cognitive bias people are more likely to remember notable or unusual examples rather than typical examples.[18] Thus, even when accurate, anecdotal evidence is not necessarily representative of a typical experience. Accurate determination of whether an anecdote is typical requires statistical evidence.[19] Misuse of anecdotal evidence in the form of argument from anecdote is an informal fallacy[20] and is sometimes referred to as the "person who" fallacy ("I know a person who..."; "I know of a case where..." etc.) which places undue weight on experiences of close peers which may not be typical.

Anecdotal evidence can have varying degrees of formality. For instance, in medicine, published anecdotal evidence by a trained observer (a doctor) is called a case report, and is subjected to formal peer review.[21] Although such evidence is not seen as conclusive, researchers may sometimes regard it as an invitation to more rigorous scientific study of the phenomenon in question.[22] For instance, one study found that 35 of 47 anecdotal reports of drug side-effects were later sustained as "clearly correct."[23]

Anecdotal evidence is considered the least certain type of scientific information.[24] Researchers may use anecdotal evidence for suggesting new hypotheses, but never as validating evidence.[25][26]

If an anecdote illustrates a desired conclusion rather than a logical conclusion, it is considered a faulty or hasty generalization.[27]

In any case where some factor affects the probability of an outcome, rather than uniquely determining it, selected individual cases prove nothing; e.g. "my grandfather smoked two packs a day until he died at 90" and "my sister never smoked but died of lung cancer". Anecdotes often refer to the exception, rather than the rule: "Anecdotes are useless precisely because they may point to idiosyncratic responses."[28]

In medicine, anecdotal evidence is also subject to placebo effects.[29]

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In the legal sphere, anecdotal evidence, if it passes certain legal requirements and is admitted as testimony, is a common form of evidence used in a court of law. Often this form of anecdotal evidence is the only evidence presented at trial.[30] Scientific evidence in a court of law is called physical evidence, but this is much rarer. Anecdotal evidence, with a few safeguards, represents the bulk of evidence in court.

The legal rigors applied to testimony for it to be considered evidence is that it must be given under oath, that the person is only testifying to their own words and actions, and that someone intentionally lying under oath is subject to perjury. However, these rigors do not make testimony in a court of law equal to scientific evidence as there are far less legal rigors. Testimony about another person's experiences or words is called hearsay and is usually not admissible, though there are certain exceptions. However, any hearsay that is not objected to or thrown out by a judge is considered evidence for a jury. This means that trials contain quite a bit of anecdotal evidence, which is considered as relevant evidence by a jury. Eyewitness testimony (which is a form of anecdotal evidence) is considered the most compelling form of evidence by a jury.[31]

See also

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Look up anecdotal evidence in Wiktionary, the free dictionary.

References

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  1. ^ "anecdata, n.", Oxford English Dictionary (3 ed.), Oxford University Press, 2023-03-02, doi:10.1093/oed/9365074374, retrieved 2024-10-03
  2. ^ a b Irwig, Les; Irwig, Judy; Trevena, Lyndal; Sweet, Melissa (2008), "The weakness of one", Smart Health Choices: Making Sense of Health Advice, Hammersmith Press, retrieved 2024-10-03
  3. ^ a b Oxford dictionary of English. Internet Archive. Oxford [England]; New York : Oxford University Press. 2010. p. 58. ISBN 978-0-19-957112-3.{{cite book}}: CS1 maint: others (link)
  4. ^ Porta, Miquel (2016-07-21), "Anecdotal Evidence", A Dictionary of Epidemiology, Oxford University Press, doi:10.1093/acref/9780199976720.001.0001/acref-9780199976720-e-60, ISBN 978-0-19-997672-0, retrieved 2024-10-03
  5. ^ Cambridge University Press (2009). Cambridge academic content dictionary. Internet Archive. New York : Cambridge University Press. p. 31. ISBN 978-0-521-87143-3.
  6. ^ "16 CFR Part 255 (Oct. 1, 2024) -- Guides Concerning Use of Endorsements and Testimonials in Advertising". eCFR. Retrieved 2024-10-03.
  7. ^ Hoeken, Hans; Hustinx, Lettica (2009-10-01). "When is Statistical Evidence Superior to Anecdotal Evidence in Supporting Probability Claims? The Role of Argument Type". Human Communication Research. 35 (4): 491–510. doi:10.1111/j.1468-2958.2009.01360.x.
  8. ^ Hornikx, J. M. A. (2007). "Is anecdotal evidence more persuasive than statistical evidence? A comment on classic cognitive psychological studies". 164.
  9. ^ Hoeken, Hans (2001-11-01). "Anecdotal, Statistical, and Causal Evidence: Their Perceived and Actual Persuasiveness". Argumentation. 15 (4): 425–437. doi:10.1023/A:1012075630523. ISSN 1572-8374.
  10. ^ Michal, Audrey (2021). "When and why do people act on flawed science? Effects of anecdotes and prior beliefs on evidence-based decision-making". Cognitive Research: Principles and Implications. 6 (1): 28. doi:10.1186/s41235-021-00293-2. PMC 8023527. PMID 33825055.
  11. ^ Hoeken, H.; Hustinx, L. G. M. M. (2003). "The relative persuasiveness of anecdotal, statistical, causal, and expert evidence". 502.
  12. ^ "anecdotal". YourDictionary.com. Retrieved 17 June 2019.
  13. ^ "Nechako White Sturgeon Recovery Initiative - Glossary - NWSRI". www.nechakowhitesturgeon.org. Retrieved 2020-04-07.
  14. ^ "Anecdotal evidence - Smart Health Choices - NCBI Bookshelf". www.ncbi.nlm.nih.gov. Retrieved 2020-04-07.
  15. ^ "No Love for Anecdotal Evidence". NeuroLogica Blog. 2007-03-08. Retrieved 2020-04-07.
  16. ^ Weiten, Wayne (2010). Psychology: Themes and Variations. Wadsworth/Cengage Learning. p. 75. ISBN 9780495601975.
  17. ^ Goodwin, C. James (2009). Research in Psychology: Methods and Design. John Wiley & Sons. p. 25. ISBN 9780470522783.
  18. ^ Gibson, Rhonda; Zillman, Dolf (1994). "Exaggerated Versus Representative Exemplification in News Reports: Perception of Issues and Personal Consequences". Communication Research. 21 (5): 603–624. doi:10.1177/009365094021005003. S2CID 145050644.
  19. ^ Schwarcz, Joe; Barrett, Stephen. "Some Notes on the Nature of Science". Archived from the original on 20 September 2012. Retrieved 16 June 2022.
  20. ^ "Fallacies | Internet Encyclopedia of Philosophy". www.iep.utm.edu. Retrieved 2020-04-07.
  21. ^ Jenicek, M. (1999). Clinical Case Reporting in Evidence-Based Medicine. Oxford: Butterworth–Heinemann. p. 117. ISBN 0-7506-4592-X.
  22. ^ Vandenbroucke, J. P. (2001). "In Defense of Case Reports and Case Series". Annals of Internal Medicine. 134 (4): 330–334. doi:10.7326/0003-4819-134-4-200102200-00017. PMID 11182844. S2CID 867759.
  23. ^ Venning, G. R. (1982). "Validity of anecdotal reports of suspected adverse drug reactions: the problem of false alarms". Br Med J (Clin Res Ed). 284 (6311): 249–52. doi:10.1136/bmj.284.6311.249. PMC 1495801. PMID 0006799125.
  24. ^ Riffenburgh, R. H. (1999). Statistics in Medicine. Boston: Academic Press. pp. 196. ISBN 0-12-588560-1.
  25. ^ Lilienfeld, Scott O.; Lynn, Steven Jay; Lohr, Jeffrey M. (2014). "Initial Thoughts, Reflections, and Considerations". Science and Pseudoscience in Clinical Psychology (2 ed.). New York: Guilford Publications. p. 9. ISBN 9781462517510. Testimonial and anecdotal evidence can be quite useful in the early stages of scientific investigation. Nevertheless, such evidence is almost always much more helpful in the context of discovery (i.e., hypothesis generation) than in the context of justification (i.e., hypothesis testing [...]).
  26. ^ Mebius, A. (2022). "Against 'instantaneous' expertise". Philosophy, Ethics, and Humanities in Medicine. 17 (11): 11. doi:10.1186/s13010-022-00123-3. PMC 9490894. PMID 36127693. S2CID 252384889.
  27. ^ Thompson B. Fallacies. Archived April 20, 2006, at the Wayback Machine
  28. ^ Sicherer, Scott H. (1999). "Food allergy: When and how to perform oral food challenges". Pediatric Allergy and Immunology. 10 (4): 226–234. doi:10.1034/j.1399-3038.1999.00040.x. PMID 10678717. S2CID 1484234.
  29. ^ "Evaluating Treatment Products". MedicineNet.
  30. ^ "The Judicial Learning Center". 10 August 2012.
  31. ^ "Benton, Ross, Bradshaw, Thomas, & Bradshaw, 2006".
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