RE: Field's comments on Cohen's Observation

[epirad@mchsi.com]

Jim,



Just for the record, what conclusion would that be?



Bill Field

> 

> Dr. Bill Field wrote:

> -----Original Message-----

> From: epirad@mchsi.com [mailto:epirad@mchsi.com]

> Sent: Monday, June 16, 2003 9:06 AM

> To: BERNARD L COHEN

> Cc: radsafe@list.vanderbilt.edu

> Subject: Re: Cohen's Observation

> 

> 

> Dr. Cohen, 

> 

>     <snip>

> 

> The reason I enter this debate is not about ego, but rather because so many 

> people including knowledgeable HPs and Physicists misinterpret your findings 

> to indicate prolonged residential radon exposure does not cause lung cancer 

> (eventhough the vast majority of case-control studies indicate it does). You 

> have stated yourself ecologic studies can not assess risk.  This needs to be 

> stated by you more often. While ecologic studies can not assess causality, 

> analytic epidemiology studies (such as case-control studies) do have the 

> ability to establish causality.

> 

> If you would have found a positive ecologic association between radon and lung 

> cancer and used that to state this proves the LNT is valid, I would be just a 

> fervent in my opposition in you using it to test the LNT because of the 

> limitations of the ecologic design.  This debate has not been about the 

> validity of the LNT, this debate has been about the limitations of ecologic 

> studies. You state the limitations inherent in ecologic studies do not exist 

> if you use an ecologic design to test the LNT, no knowledgeable epidemiologist 

> would agree with such a contention.  

> 

> The validity of the LNT should be tested, but not by such a weak tool as an 

> ecologic study. 

> 

> I am sure there are many other areas we do agree on, but the proper use of an 

> ecologic study is not one of them. 

> 

> Regards, Bill Field

> 

> ====================

> 

> Dr. Cohen has always clearly stated the conclusion that he believes his analysis 

> of the county data supports and should not be responsible for 

> mis-interpretations or mis-representation of those conclusions.

> 

> From LNT, it follows as the night the day that radiologically-induced cancer 

> incidence (and cancer mortality, given reasonably uniform standards of 

> treatment) is a linear function of person-rem exposure.  As such, an ecologic 

> study is adequate to test the LNT, assuming dependence and confounding issues 

> can be handled.  

> 

> To even suggest that Dr. Cohen might have tried to prove the validity of LNT 

> using his or any other data set misunderstands the nature of the scientific 

> method, at least in the Popperian formulation.  Nature whispers yes and shouts 

> NO.  An experiment whose results conform to the predictions of a theory does not 

> "prove" validity of the theory.  It may gives us a warmer feeling about the 

> theory.  Many confirmatory experiments may lead us to believe to a high level of 

> confidence that the theory is true, but they do not "prove" its truth.  "Proof" 

> is a concept that lives in Mathematics not in Science.

> 

> On the other hand, a theory may make predictions that are falsifiable, in the 

> sense that we can design and perform an experiment whose outcome is capable of 

> contradicting the predictions of the theory.  If we were perform the experiment 

> and the results indeed contradict the predictions of the theory, then we need a 

> new theory.  To many, including me, Cohen's dataset and his analysis look very 

> much like such an experiment.

> 

> Finally, "knowledgeable epidemiologists" believe a number of weird things, case 

> in point being Rothman's assertion a while back that epidemiologists didn't need 

> to bother with the Universal Null Hypothesis in their consideration of whether 

> their data said something meaningful or was simply a reflection of random 

> variation.

> 

> Best regards.

> 

> Jim Dukelow

> Pacific Northwest National Laboratory

> Richland, WA

> jim.dukelow@pnl.gov

> 

> These comments are mine and have not been reviewed and/or approved by my 

> management or by the U.S. Department of Energy.

> 

> 

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