The benefit in AIDS prevention is established in a study (three simultaneous studies run at the same time by the same people using same methodology) that has some flaws:

– The circumcised group was told not to have sex for a month after circumcision.
– Both groups received safe sex counseling and condoms, but the intact group had fewer sessions.
– The benefit was the greatest during the first few months of the experiment and the difference shrunk later in the experiment (makes some sense since the circumcised group did not start when the intact group did).
– The experiment was cut short – the researchers stopped it two months early and circumcised the intact group.
– The observed (shrinking) difference was projected into the future for the length of active sexual life without accounting for the trend (shrinking). Since the intact group was destroyed it is not possible to validate the assumption.
– The experiment with ‘female circumcision’ ran at the same time showed similar benefits, but in that case the researchers discounted the benefits as the result of late start, physical discomfort and more frequent counseling for the circumcised group (same factors were ignored with the male population).
– The experiment ran in a part of the world where soap, running water, warm water and education are luxury.

Might be a case of getting a grant and bending the procedure to meet the desired outcome.