Anecdotal evidence refers to when information regarding a phenomenon, activity, or event comes from direct experience or opinions of individuals.
Anecdotal evidence is often shared organically through conversation, such as with old wives’ tales, and may become more credible when people attest to it.
People can be easily influenced by anecdotal accounts and will often follow the advice of someone just based on that individual’s recommendation.
However, advice based on anecdotal evidence can be misleading, sometimes even dangerous, a requires rigorous testing for it to be truly trustworthy empirical evidence held with esteem by scientists and experts.
Anecdotal Evidence Examples
- Weather Predictions: A person might claim that they can predict the weather based on their observation of specific environmental factors, such as the appearance of certain clouds or the behavior of animals. While these predictions might be accurate occasionally, they are not grounded in scientific data or meteorological expertise.
- The Quitter who Landed on his Feet: A man who quit his job with very little savings ended up finding another, even better, job three weeks later. Now, he recommends to anyone who’s unhappy in their job to quit because you’ll land on your feet, too – just like him.
- Supplement Effectiveness: People might claim that a particular dietary supplement or natural product greatly improved their health or cured a specific ailment. These testimonials often lack scientific support but can still influence the decisions of others seeking similar results.
- Bad consumer experience: A man travels on a 10-hour flight with a big brand airline and has a horrible time. Twenty years later, he still says that brand is the word brand of airline in the world.
- Sensationalized media: Often, the media presents outlier case studies due to their sensational nature. But media reports are often simply sensational anecdotal evidence that the reporters have found rather than statistical data.
- Bad parenting: A man decides his neighbor is a terrible parent because he saw her one day unable to control her child. He didn’t see all the other examples of when that woman was being an excellent mother
- Observing that Opposites Attract: Sometimes,anecdotal evidence can be accurate. For example, the common saying that “opposites attract” is based on anecdotal evidence of people observing the oddity of couples that don’t seem to match. Lately, research has studied the validity of this anecdotal evidence. The key finding: romantic relationships are about balance.
- Life Lessons: Life lessons passed on from generation to generation may not be based in the scientific method, the this kind of anecdotal evidence has a lot of credibility nonetheless. For example, a father who tells his son not to get involved in a bad relationship comes from his anecdotal experience, but it’s also great advice.
- Home Remedies: People often share personal anecdotes about the effectiveness of home remedies for various ailments. These stories are based on individual experiences rather than scientific evidence, but they can still influence others to try the remedies themselves.
- Career Advice: A successful professional may offer career advice based on their personal experiences, attributing their success to certain behaviors or decisions. While these anecdotes might be inspiring, they don’t necessarily guarantee similar results for everyone who follows the same path.
- Anecdotal Evidence in Scientific Communication: When anecdotal evidence comes from a trusted expert, it can be very persuasive. As a result, scientists often teach concepts like climate change by appealing to anecdotal evidence (e.g. ‘you’ve noticed it’s gotten hotter since your childhood’). This is actually part of Petty and Cacioppo’s (1986) Elaboration Likelihood Model of Persuasion.
- Product Reviews: A friend raves about a new gadget or appliance that they recently purchased, claiming it has made their life easier. This anecdotal evidence might be compelling, but it doesn’t provide a comprehensive evaluation of the product’s overall quality and effectiveness.
- Superstitions and Beliefs: People may believe in certain superstitions or rituals based on anecdotal evidence. For example, someone might avoid walking under ladders due to a story they heard about someone experiencing bad luck after doing so, despite the lack of any statistical correlation between the action and the outcome.
- Stereotyping: We’ve all heard the saying “birds of a feather flock together.” This is an example of anecdotal evidence where a person stereotypes a whole group of people based upon their experience with one person from within that group.
- Weight Loss Success: Individuals might share stories of losing weight through a specific diet or exercise routine. While these anecdotes can be motivating, they may not be universally applicable or supported by scientific research on the most effective weight loss methods.
- Pet Behavior: Pet owners may share anecdotes about their pets’ unique behaviors or training techniques that have worked for them. These stories, while interesting, might not be applicable to all pets or provide reliable information about animal behavior in general.
- Tennis Player’s Routine: A tennis player has the best game of his life one day after eating three eggs for breakfast. He’s so convinced by this anecdotal evidence that every game day has two start with three eggs and a big cup of coffee or else he’s convinced he will lose the game.
- Effective Study Habits: Students might claim that a specific study technique such as the pomodoro method led to their academic success. So they tell their friends to follow the advice, too. Unfortunately, the pomodoro technique may not work for everyone as we all have our own unique motivations and learning preferences.
- Lucky Charms: A person might carry around a lucky charm in their wallet because the day they found the lucky charm was a very good day for them. They suggest others buy these lucky charms, too, based on their own anecdotal evidence about the charms.
Levels of Evidence: Anecdotal Evidence Ranks Low in Reliability
Practicing psychologists (APA, 2006) rely on a hierarchy of evidence which identifies the degree of validity of evidence based on stringent research parameters.
According to Stegenga (2014), “An evidence hierarchy is a rank-ordering of kinds of methods according to the potential for that method to suffer from systematic bias” (p. 313).
Based on Isoz (2020).
As seen in this graphic, at the bottom of the hierarchy is anecdotal evidence, which carries no scientific weight and has the highest degree for potential bias.
Is Anecdotal Evidence Ever Useful?
Although anecdotal evidence is not grounded in science or produced as a result of a scientific study, it does have some limited value.
For instance, a person’s description about an experience can be used as a starting point to understanding a given phenomenon.
If several people have similar descriptions, then it may inform a scientist as to common characteristics of an experience which may be the impetus for a scientific inquiry.
In other cases, it is the errors in judgement as a result of anecdotal recollections that can lead to insights into perception and decision-making.
Case Studies of Anecdotal Evidence
1. The Many Insights of Jean Piaget
Jean Piaget was a Swiss psychologist that developed an incredibly insightful theory of cognitive development. It is a theory that has driven decades of research and become a cornerstone of developmental psychology.
Even though Piaget was a trained professional, his methodology was nearly 100% anecdotal. He observed each of his children and took exhaustive notes on their behavior.
On the emergence of the deliberate action of a newborn, as evidence of intent:
“The child discovers in this way that which has been called in scientific language the “experiment in order to see” (p. 266). The infant is attempting the “discovery of new means through active experimentation” (Piaget, 1956, p. 267).A few years later, Piaget provides anecdotal evidence for what will become officially known as egocentrism. Here is a sample of his observations from The Language and Thought of the Child (1959).
“Our notes show…that at the beginning of his fourth year the child’s speech shows a greater coefficient of ego-centrism (i.e., it is less socialized in character) when speaking with adults than children of his own age (71.2% against 56.2%)” (p. 143).
Piaget had no right to make scientific claims based on this data – it’s purely anecdotal. Nevertheless, it still rings true to this day. Sometimes, anecdotal evidence turns out to be true.
2. Anecdotal Evidence and Criminal Prosecutions
Every year in the United States, thousands of people are convicted of crimes based on eyewitness testimony. That is, based on anecdotal evidence. Most of those witnesses are quite confident in their accounts.
However, psychologist Dr. Elizabeth Loftus (1997) has demonstrated that this form of anecdotal evidence can be quite unreliable.
In fact, under certain conditions, false memories can be created that “feel” accurate, but are not.
“False memories are constructed by combining actual memories with the content of suggestions received from others” (Loftus, 1997, p. 75).
One of the first studies was conducted by Loftus and Palmer (1974), which demonstrated that memory could be easily altered simply by changing the way a question is phrased.
This line of research has had a tremendous impact on law enforcement and the credibility of eyewitness testimony.
Anecdotal evidence refers to information that comes from our own experience or someone else’s. It can be very persuasive, especially if it comes from a credible source, such as an expert or trusted friend.
As a source of scientific evidence however, it is considered unreliable. There are many possible biases that can undermine the validity of anecdotal evidence.
Although often harmless, in some contexts, anecdotal evidence can be quite dangerous. For example, research has demonstrated that eyewitness testimony can be easily manipulated.
On the other side of the coin however, anecdotal evidence can be the impetus for a new line of scientific inquiry.
Nearly all of Piaget’s theory of cognitive development was based on anecdotal evidence he gathered by observing his own children. And let’s not forget that our understanding of bystander intervention was sparked by anecdotal accounts of a terrible tragedy.
So, while scientists tend to discount the value of anecdotal evidence, it has played a significant role in many highly influential in psychological studies.
APA Presidential Task Force on Evidence-Based Practice (2006). Evidence-based practice in psychology. The American Psychologist, 61(4), 271–285. https://doi.org/10.1037/0003-066X.61.4.271
Carlyle, T. (1869). Heroes and hero-worship (Vol. 12). Chapman and Hall.
Darley, J. M., & Latané´, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8, 377–383.
Isoz, V. (2020). International System of Scientific Evidence Levels (version 2020).
Petty, R.E. and Cacioppo, J.T. (1986). The Elaboration Likelihood Model of Persuasion. Advances in Experimental Social Psychology, 19, 123-205. doi: https://doi.org/10.1016/S0065-2601(08)60214-2
Piaget, J. (1956; 1965). The origins of intelligence in children. International Universities Press Inc. New York.
Stegenga, J. (2014). Down with the hierarchies. Topoi, 33(2), 313-322.
Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207–32. https://doi.org/10.1016/0010-0285(73)90033-9
Youyou, W., Stillwell, D., Schwartz, H. A., & Kosinski, M. (2017). Birds of a feather do flock together: Behavior-based personality-assessment method reveals personality similarity among couples and friends. Psychological Science, 28(3), 276–284. https://doi.org/10.1177/0956797616678187
Apendix: Hierarchy of Evidence in Text Format
|Stage||Type of Evidence|
|1 – Weakest||Testimonials, anecdotals, traditions, quotes, folk lore, YouTube videos|
|2||Newspapers, editorials, magazines|
|3||Non-replicated case studies|
|4||Longitudinal and cross-sectional evidence|
|5||Blind randomized control studies|
|6 – Strongest||Meta-analyses and systematic reviews|