Re: Radon and Lung Cancer: What the studies really say.

[BERNARD L COHEN <blc+@PITT.EDU>]

On Fri, 20 Jun 2003 epirad@mchsi.com wrote:



> Unlike ecologic studies, case-control studies differ in that in a case control

> study you directly measure the radon concetration in a home and with subject

> mobility, the radon concentrations can be linked to mobility to get an estimate

> of exposure. The ecologic studies use a few short term measurments per home

> (with a high percentage in the basement) while the case control studies use

> year long living area measurements.  In an ecologic study exposure

> nondifferential misclassification can cause unbounded extreme biases while in a

> case-control study nondifferential misclassification reduces the risk estimate.



	--The justification for my radon levels is spread over several of

my papers and would not be easy to justify briefly here. The best

references I can give are in Sec. D of Item #1 on my web site, and Ref.

(Cohen 1992c) in that paper. Biases are discussed in the former. The

briefest justification I can give is to say that my radon levels correlate

strongly with those obtained by EPA and by State=sponsored measurements,

and all three give the same results when used in my analyses.



> In a case control study, if you obtain retrospective information on radon

> progeny, you can calculate dose.



	--The great majority of case-control studies do not obtain retrospective

information on radon



	--Case-control studies have many weaknesses, some of which are

mentioned in Sec. 6 of Item #7 on my web site.



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