-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sun, 05 Jun 2005 14:12:08 -0700 Andrew Lentvorski <[EMAIL PROTECTED]> wrote:
> David J. Looney wrote: > > > Studies from which you can draw > > conclusions don't necessarily have to be randomized, blinded, and > > controlled, but case studies need carefully chosen controls in order > > to be meaningful. > > Not necessarily. > > Statistics is often used to tease out the independent variables in > "messy" data. > > Much of the original AIDS work and identification was done in this > way. Statistical anomalies are only anomalous with respect to some norm. Data mining is most likely to work only if the data is not biased. The "control" in this case was historical. These very rare diseases (Kaposi's sarcoma and Pneumocystis carinii pneumonia) were simply never seen in young men without leukemia, etc., in the U.S. before. It was immediately obvious to most that something new and different was happening. That it was infectious, and a virus, and sexually transmitted were all good hypotheses. But to prove that HIV was associated with AIDS, there had to be cases and controls. > It is less reliable, but sometimes you need an answer *now*. Waiting > was unacceptable. People began forming hypotheses and adjusting > behavior long before people knew exactly what was going on. True, waiting was unacceptable. Part of the response to any emergency is to be to determine what can be done to ameliorate risk, based on inadequate data and a large number of potential causes. In many communities of men who have sex with men, there was a high risk of sexually transmitted infection, a high frequency of havning multiple partners, and also a higher prevalence of use of some drugs than the general community (a control), which didn't seem to be getting these unusual infections. Certainly it was not unreasonable to say, "Hey, this may be infectious, maybe we ought to close the bath houses until we get more data and find out for sure ! And maybe we ought to stop using drugs. And we should should be using condoms anyway." But an important part "not waiting" was to approach the problem in a controlled fashion. Many of those initial hypotheses were dead wrong (e.g. amyl nitrite, immune suppression due to exposure to histocompatibility antigens from multiple partners). Some people acted on anecdotal data by limiting themselves to just a few sexual partners, or discontinuing use of poppers while continuing to have unprotected sex. This was unwise. To test the hypotheses, controlled data was needed. > Often, > conclusions drawn on fairly thin evidence become embedded as facts in > the medical community. I agree. They are only exorcised by studies which use controlled data. BTW, in what enlightened community does this not occur ? David Looney - -- Life is short, and the Art long; the occasion fleeting; experience fallacious, and judgment difficult. - Hippocrates -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCo31vZnDUcKSydkURAn1iAJ4pRs9ztZnUux+1uoJyuZpOhU4/9wCcCac/ o98iMyp1HcWfr6mRrOoI6gg= =3twO -----END PGP SIGNATURE----- -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
