2007-08-19

Male genital mutilation will be proved to be as useless as telepathy

After following the male circumcision and HIV debate for some time, and trying to make sense of the published scientific literature, I happened upon an article by Susan Blackmore in the Guardian which should clarify the situation.

To me it is just basic common sense that natural, intact anatomy does not cause disease or other health problems. Indeed, all the published scientific articles which purport to show that circumcision reduces the incidence of sexually transmitted infections other than HIV have been discredited or are based on outdated information and invalid statistics. Which leaves the three published randomized trial studies which WHO/UNAIDS is basing its current pro-circumcision policy on. Although these studies were unethical and poorly controlled, and have been severely criticised, they have not yet been formally rebutted, which leaves us with lingering doubts.

Fortunately, Blackmore gives us a good reason to believe that the studies will ultimately be discredited or found to be quite irrelevant. She used to believe in the effectiveness of extra-sensory perception (ESP), and was
an active researcher in parapschycology for a number of years. Finally, after conducting numerous studies, none of which showed statistically significant positive results, she convinced herself of its ineffectiveness. A description of the process she went through is given in her 1987 article in the Skeptical Inquirer, The Elusive Open Mind: Ten Years of Negative Research in Parapsychology

Quoting from her article:
However, I did have an idea. There were still things in which I did believe. I could test the Tarot. In my preoccupation with everything occult, I had been reading Tarot cards for about eight or nine years. They really did seem to work. People told me that I could accurately describe them using the cards, and this was, naturally, gratifying. I even thought it might have a paranormal basis. So I set about testing the cards, doing readings for ten people, keeping the procedure as close as possible to a normal Tarot reading, but isolating myself, as the reader, from the subjects. They then had to rank all ten readings to see whether they picked their own more often than chance would predict (Blackmore 1983).

It worked! The results were actually significant. You can imagine my excitement--perhaps I had at last found something. Perhaps there was no psi to be found in the standard laboratory experiments, but something paranormal could appear when the conditions were closer to real life. But then I talked to Carl Sargent. He pointed out that all my subjects knew one another, and if they knew one another their ratings and rankings could not be independent. So I had violated an assumption of the statistical test I was using.

This seemed so trivial. Their knowing one another could not help them pick the right reading, could it? No it couldn't; but this meant that the estimate of probability was inaccurate--and, after all, the results were only marginally significant. So I repeated the experiment twice more with subjects who did not know one another. I expect you can predict the results I obtained--entirely nonsignificant.

So her initial experiment was rendered valueless merely because her subjects knew each other!

We thus see how easy it is to obtain apparently statistically significant results which are entirely spurious. Given the numerous confounding factors, and the motivations of the researchers conducting the circumcision/HIV trials, I am now confident that their "compelling" results will eventually be found to be completely unreliable, and to have a scientific value no greater than that of reportedly "positive" ESP experiments.