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Re: Confounders and Coincidences
Dr. Cohen,
I believe Dr. Raabe is correct. Using your example, in a case-control study you can match cases to controls via ethnicity - you can not do this in an ecologic study such as your regardless of the sample size.
----- Original Message -----
From: BERNARD L COHEN <blc+@PITT.EDU>
Date: Tue, 06 May 2003 11:15:25 -0400 (EDT)
To: "Otto G. Raabe" <ograabe@UCDAVIS.EDU>
Subject: Re: Confounders and Coincidences
>
> On Mon, 5 May 2003, Otto G. Raabe wrote:
>
> > case-control and cohort studies. In these studies unknown confounders are
> > considered by proper control selection procedures and sufficient sample
> > sizes.
>
> --How can you say this? As a counter-example, suppose people of a
> certain ethnicity have a tradition of keeping their homes well sealed,
> which would give higher radon levels. Suppose further that people of
> that ethnicity have a genetic disposition to getting lung cancer. Then
> ethnicity would be an important confounding factor, indicating that high
> radon causes lung cancer.
>
> > In ecological studies there are no rigorous control selection
> > procedures since we don't know who is exposed to what.
> >
--
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