Saturday, April 20, 2013

How to make shams like homeopathy sound more plausible

Homeopathy is most certainly not the only snake oil salesmanship out there that's a pure sham, but it's probably the one that makes the most money worldwide. (There are other shams that may make more money than homeopathy, but they are usually not related to selling supposedly medicinal products.)

Homeopathic products are 100% placebos, pure and simple, yet it's taken really seriously among many people, and many claims of successful clinical studies and efficacy abound. There are published papers and lots of positive experiments that claim that homeopathy fares much better than placebos in properly-conducted double-blind trials.

But how can there be, given that homeopathic products are just placebos? It's not hard to get such results. There are some simple tricks that can be used for this. For example:

  1. When conducting an experimental trial, minimize the amount of test subjects. For example, rather than testing on 500 people, test on 20.
  2. Engage in confirmation bias: Highlight individual cases where the result was favorable to the homeopathic test, and belittle or ignore the cases where it was unfavorable.
  3. More effectively, though, perform many trials, and publish results for only those that gave a clearly positive result, while ignoring those that did not (in other words, engage in publication bias.) If you perform, for example, 50 trials, just by statistical probability you are going to get at least two or three that seem to indicate that homeopathy has a significantly greater effect than placebos (while the rest of the trials will show no difference, a few even showing a negative correlation.) Take the results of those two or three and publish them; ignore the rest.
  4. Publish your results in a publication with low standards of quality but a big name among homeopaths.
And there you have it. Several publications of "properly conducted" trials that clearly show that homeopathic remedies have a better effect than placebos. Now homeopaths can argue their position with "credible" references to "peer-reviewed" publications of clinical trials that "clearly" show the efficacy of homeopathy.

And when actual scientists perform the same clinical trials and see no difference to placebos, just claim that it's them who are biased, and that they are just trying to attack homeopathy because they want to eliminate competition and retain the monopoly. This is an easy claim to make because nobody will actually go through the trouble of finding out if there's any truth to it.

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