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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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