“You can just put an onion in a sock and lay it on your child’s chest to reduce the fever from measles. I’ve heard from people who say that it works!”
This is an honest-to-God post I read on an anti-vaccine forum (albeit a slight paraphrasing). To set the record straight, there is absolutely no scientific or medical reasoning, research or evidence to suggest that this works. This post on the forum is what we call anecdotal evidence. Little stories with (a lack of true) evidence based on hearsay, that is, information passed on by word-of-mouth.
The truth hurts
The internet is rife with forums providing anecdotal evidence, mostly to do with cancer cures, ‘natural’ remedies and detox diets, and all lacking true bona fide rigorous, peer-reviewed evidence. So why does it appear that people choose to believe anecdotal evidence over true facts? According to Scientific American it has to do with the outcome.
Anecdotal evidence usually involves believing that there is a relationship between two things, which leads to a ‘false positive’ harmless result, while believing that there is no connection between two things could lead to a harmful result. Doesn’t make sense? Basically it means that it is easier to believe a non-existent relationship if it promises an answer that you want, rather than the evidence to the contrary. This has to do with the human tendency to seek out patterns and look for relationships between things that don’t actually exist in order to avoid the truth of the situation.
This is the opposite to scientific rigour, which normally involves trying to disprove a relationship between two things, and acts to avoid generating false positive results.
It comes down to hurt feelings
It is a mystery to me (and I might add, frustratingly so) that people choose to believe word-of-mouth over scientific evidence, whether it is to prove or disprove something. However, scholars investigating anecdotal evidence believe that the strength of belief in anecdotal evidence stems from the boundaries between the ‘experts’ (scientists, doctors etc) and the ‘lay’ people (the general public). As scientific knowledge increases, so-called ‘lay’ experts are disproven or disregarded and thus their previous position in the lay-society is lowered. So they argue against the ‘experts’.
Besides the multitude of websites and forums helping to unite ‘lay experts’, the media also plays a role. An example of this is a case regarding mobile phones and brain cancer. In this particular example, an individual decided to sue a mobile phone company as he blamed them for his wife’s brain cancer. Although there was no evidence to back up this claim, the media promoted it as a true fact. This has spawned public belief that mobile phones cause brain cancer, when in actual fact, a very large meta-analysis of studies investigating if phones cause cancer found no evidence to support these claims.
Last, but not least, anecdotal evidence can also be presented in the form of testimonies, which is almost always used to promote a product or an agenda.
Think, ‘by drinking this product, I lost 20 kgs in one week!’ Another, and very famous example of using testimonies based on anecdotal evidence is the response to the editors by Andrew Wakefield after his paper describing a (supposed) link between autism and the MMR vaccine was retracted for being fraudulent. He wrote:
Clinician’s duties are to their patients, and the clinical researcher’s obligation is to test hypotheses of disease pathogenesis on the basis of the story as it is presented to him by the patient or the patient’s parent’’ (Wakefield 1998, 905; italics mine). Parents have said ‘‘‘my child has a problem with his/her bowels which I believe is related to their autism’’’….
I have hesitated writing about vaccines and autism as I don’t really want to deal with the responses that will no doubt appear, however the statement made above is a perfect example of anecdotal evidence. Wakefield wrote that the parents conclusion about their child’s symptoms was evidence enough to demonstrate a link between the MMR vaccine and autism, when what he really had was anecdotal evidence. I don’t really want to delve into this debate any further because it has been demonstrated time and time again, including in a massive meta-analysis, that there is no link.
Final thoughts (and I am preparing for the onslaught)
So what do we learn from this? To me, it seems, that people want to believe in anecdotal evidence because it is easier to believe than actual peer-reviewed research and evidence-based data.
I also feel that it is because with anecdotal evidence, people feel that they do not need to be held accountable for whatever it is they are talking about, despite often pushing an agenda, or trying to discredit the experts. It is also frustrating that (as an expert) you can tell someone until you are blue in the face that ‘no, that is not true’, and they still will not believe you! The latter statement is supported by scholars who wrote that:
…anecdotal evidence is used to demarcate the boundaries of science…and as a site for contestation and negotiation between experts and lay actors in public scientific controversies….
So next time you hear someone say “it’s true, it happened to a friend of a friend” or “I read about it on X, Y, Z”, please question the source and the actual scientific-based evidence!