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RE: Re: Cohen's Fallacy
That is the question I have asked Dr. Cohen to explain numerous times.
Please provide a definitive explanation as to why the radon concnetrations
show a rather large inverse correlation with smoking?
>From: Jack_Earley@RL.GOV
>Reply-To: Jack_Earley@RL.GOV
>To: radsafe@list.vanderbilt.edu
>CC: motnivas@YAHOO.COM, tjsav@LYCOS.COM
>Subject: RE: Re: Cohen's Fallacy
>Date: Mon, 28 Jan 2002 07:06:07 -0800
>
><<smoking status and residential radon are uncorrelated within each county
>(which seems unlikely)>>
>
>Okay, now it's my turn to be stupid(er). How could smoking status possibly
>correlate with residential radon? Are smokers now congregating in high
>radon
>or low radon subdivisions?
>
>Jack Earley
>Radiological Engineer
>
>
>-----Original Message-----
>From: Thomas J Savin [mailto:tjsav@LYCOS.COM]
>Sent: Sunday, January 27, 2002 5:21 PM
>To: radsafe@list.vanderbilt.edu
>Cc: motnivas@YAHOO.COM
>Subject: Fwd: Re: Cohen's Fallacy
>
>
>Apologies galore - its just that I did not receive my message from radsafe
>-
>so I am sending it out again. I think my message speaks for itself. There
>is definitely a point for which I address.
>---
>Tom Savin
>
>--------- Forwarded Message ---------
>
>DATE: Sun, 27 Jan 2002 18:06:55
>From: "Thomas J Savin " <tjsav@lycos.com>
>To: "Rad health" <healthrad@HOTMAIL.COM>
>
>It seems to me that some of this scientific debate is concerned with Type I
>and type II errors. In other words, does one subscribe statistically to
>whether or not they are biased to avoid a false positive vs a false
>negative
>result. Which camp do they support? Any Comments? Tom
>---
>Tom Savin
>
>On Sun, 27 Jan 2002 16:21:20
> Rad health wrote:
> >After reading the epidemiologic technique in the paper Dr. Field
>suggested
> >to Dr. Cohen, I think it could possibly help to correct the problem with
> >Cohen's analyses pointed out here by Doll and Darby. This is the same
> >problem Field pointed out previously of the radon varying more within
>county
> >than between counties. The variance of smoking within county
>co-correlates
>
> >with other factors that Cohen has not been able to treat at the within
> >county level.
> >
> >Don
> >
> >J. Radiol. Prot. 20 (June 2000) 221-222
> >
> >LETTER TO THE EDITOR
> >
> >Reply to `Explaining the lung cancer versus radon exposure data for USA
> >counties'
> >
> >Sarah Darby and Richard Doll
> >Clinical Trial Service Unit, University of Oxford, Nuffield Department of
> >Clinical Medicine, Harkness Building, Radcliffe Infirmary, Oxford OX2
>6HE,
> >UK
> >
> >Professor Cohen states in his letter that his analysis `encompasses all
>of
> >the Doll suggestions'. It is, however, logically impossible for it to
>have
> >done so using data at the level of counties. This is because the effect
>of
> >cigarette smoking on the relationship between residential radon and
> >individual lung cancer risk will be determined by the relationship
>between
> >smoking status and lung cancer among the individuals within each county.
> >Unless smoking is irrelevant to lung cancer risk (which we know to be
> >untrue) or smoking status and residential radon are uncorrelated within
>each
> >county (which seems unlikely), the relationship between residential radon
> >and lung cancer at the county level will differ from that at the level of
> >the individual in a way that cannot be overcome by including corrections
>for
> >smoking habits at the county level, even if these corrections correctly
> >represent the smoking habits of the individuals within each county. The
> >difference in the relationship between a risk factor and a disease rate
>at
> >the level of the individual and at an area level is the ecologic fallacy
>and
> >is described in detail by Greenland and Robins (1994) and Morgenstern
> >(1998). Lubin (1998) has also demonstrated that biases caused by the
> >ecologic fallacy can be of any magnitude from minus infinity to plus
> >infinity.
> >
> >In two recent studies (Lagarde and Pershagen 1999, Darby et al 2000),
> >parallel individual and ecological analyses have been carried out of
> >identical data from case-control studies of residential radon (Peshagen
>et
> >al 1994, Darby et al 1998). These analyses have shown that, in addition
>to
> >any bias caused by the ecological fallacy, ecological studies of
>residential
> >radon and lung cancer are also prone to biases caused by determinants of
> >lung cancer risk that vary at the level of the ecological unit concerned.
>In
> >these two examples, the additional variables were latitude and
>urban/rural
> >status respectively. The explanation of these variables is not yet well
> >understood and they may well be, in part, surrogate measures for some
> >aspects of the subjects' smoking history not accounted for by the
>measures
> >of smoking status that have been derived from the individual
>questionnaire
> >data and used in the analysis of the data for individuals. They had only
>a
> >minor effect on analysis at this level but a substantial effect on the
> >ecological analyses. The presence of these variables is further evidence
>of
>
> >the pitfalls of ecological studies.
> >
> >
> >
> >_________________________________________________________________
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> >
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> >
>
>
>
>
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