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Re: st: general statistical reasoning question in biomedical statistics (no Stata content)


From   Mike Lacy <Michael.Lacy@colostate.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: general statistical reasoning question in biomedical statistics (no Stata content)
Date   Fri, 12 Dec 2003 09:32:19 -0700

statistics (no Stata content)

Having read the Statalist FAQ, and previous correspondence about general
statistical questions, I hope no one minds . . . .

>Among my teaching duties in my medical school and family practice
>residency is "critical appraisal of the medical literature." I try to
>go over principles of good design and valid analysis. A question
>frequently comes up when we discuss randomized controlled trials. In
>these articles, there is almost always a "Table 1," that describes the
>baseline demographic and clinical variables of the two arms (say,
>placebo and active drug, for example.) There are usually *a lot* of
>baseline measurements. Each one is usually listed with a "P value,"
>indicating whether the placebo and active drug subjects differed on that
>measurement.

I would agree in thinking this a misguided practice. First of all, it implicitly rests on and reinforces the notion that a small p-value indicates an important difference. Secondly, as K. Rothman noted somewhere (and I believes demonstrates with a simple example--can't remember), whether the difference ab initio is "significant" is a different matter than whether it is large enough to cause problems with assessing the treatment effect in a randomized trial.

Regards,

Regards,
=-=-=-=-=-=-=-=-=-=-=-=-=
Mike Lacy
Fort Collins CO
(970) 491-6721 office





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