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Double-Blind Studies: A Major Scientific Advance of the 20th Century, by Steven Bratman, M.D. Read this article; it isn’t terribly long, and is well worth your time. As an added bonus: I often come off as strictly anti-alternative-medicine
, whereas I would prefer to be anti-quackery, whether alternative
or conventional
in guise: This article does mention the endemic problem with lack of proper testing in alternative medicine, but it does not shy away from using a great many examples of conventional medicine gone wrong. This is good, and this is important. Quackery should never get a free pass just because it looks like good medicine (nor should good medicine be rejected because it looks like quackery under the banner of alternative
, where only good experimentation can ferret it out).
Now, you really ought to go read the whole thing—but I cannot resist posting a few gems here…
Pro primo: An example of the power of the placebo effect—and lest you think that only alternative medicine
quacks are ever confounded by it, take due notice of the fact that this refers specifically to an allopathic
treatment—surgery, no less. (Did you know, by the way, that surgical procedures exhibit a stronger placebo effect than pills, or indeed any other treatments?)
The placebo effect almost always comes as a surprise to those who experience it. Both doctors and patients are fooled. For example, surgeons used to think that arthroscopic surgery for knee arthritis really worked, and hundreds of thousands of such surgeries were performed every year. Then a study came out showing that fake surgery produces just as satisfactory and long-lasting benefits as the real thing.⁷ Surgeons were shocked and chagrined to find that people given the fake surgery (unbeknownst to them) were so pleased with the results that they said they would happily recommend the treatment to others!
People generally get angry if you tell them their benefits might be due to placebo. However, examples abound to show just how possible this really is. […]
Pro segundo: A substantiated demonstration of why clinical experience by medical professionals (alternative or otherwise) is not reliable evidence:
Observer bias is a similar phenomenon, but it affects doctors rather than patients. If doctors believe that they are giving a patient an effective drug, and they interview that patient, they will observe improvements, even if there are no improvements. For a classic example of this consider the results of a study that tested the effectiveness of a new treatment regimen for multiple sclerosis by comparing it against placebo treatment.⁹ This was a double-blind study, and therefore the physicians whose job it was to evaluate the results were kept in the dark about which study participants were receiving real and which were receiving fake treatment (they were “blinded”). However, the experimenters introduced an interesting wrinkle: they allowed a few physicians to know for certain which patients were receiving treatment (they were “unblinded”).
The results were a bit appalling. The unblinded physicians were much more likely to “observe” that the treatment worked compared to the impartial blinded physicians. In other words, the unblinded physicians hallucinated a benefit because they expected to see one! (I call this appalling because of what it says about so-called “professional objectivity.” It implies that the considered opinion of a practicing physician may be highly unreliable when it is based on professional experience rather than double-blind studies.)
Dr. Bratman goes over, in itemised form, the problems of (and I quote)
- The Placebo Effect
- The Re-interpretation Effect
- Observer Bias
- Selection Bias
- Natural Course of the Illness
- Regression to the Mean
- The Study Effect
- Statistical Illusions