The “It Worked for Me” Gambit Explained
https://www.sciencebasedmedicine.org/the-it-worked-for-me-gambit/
"It is almost inevitable that whenever we post an article critical of the claims being made for a particular treatment, alternative philosophy, or alternative profession, someone in the comments will counter a careful examination of published scientific evidence with an anecdote. Their arguments boils down to, It worked for me, so all of your scientific evidence and plausibility is irrelevant.
Both components of this argument are invalid. Even if we grant that a treatment worked for one individual, that does not counter the (carefully observed) experience of all the subjects in the clinical trials. They count too I would argue they count more because we can verify all the important aspects of their story.
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Placebo effects are largely an illusion of various well-known psychological factors and errors in perception, memory, and cognition confirmation bias, regression to the mean, post-hoc fallacy, optimism bias, risk justification, suggestibility, expectation bias, and failure to account for multiple variables. There are also variable (depending on the symptoms being treated) and subjective effects from improved mood and outlook.
Concluding from all of this that a treatment worked, when a treatment appears to be followed by improved symptoms, is like concluding that an alleged psychics power worked whenever their random guessing hits. This is why anecdotal experience is as worthless in determining if a treatment works as is taking the subjective experience of a target of a cold reading in determining if a psychics power is genuine.
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This is knowledge that can help everyone help themselves and others.