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Testing the validity of the LNT



Otto and Bill,

I think what your asking is that someone explain why a specific relationship was found using a formula that is not the LNT formula.  What type of relationship should be found using the Cohen derived formula, if his formula is not an LNT formula?  The point I made a couple days ago is that you can only hope to test the LNT if you factor in smoking duration and intensity in the initial formula since that is the only way the dose (concentration in this case) - response has a chance of being linear, if you do not do that you are not testing a LNT formula.

I have no idea what results Cohen's derived "LNT" formula should produce.  I think what he is seeing is correct for his formula. 

A quote from our previous letter, "Cohen (1999a) continues to challenge scientists to suggest a plausible explanation to explain the inverse relationship he notes between mean county residential radon measurements and mean county lung cancer mortality rates. We will call this inverse relationship "Cohen's Paradox." Cohen (1999a) states that his challenge is for someone to suggest a "not implausible model" as a possible explanation and that the burden of proof will be on him to show that "the explanation is highly implausible." We maintain that even if additional plausible models are offered, Cohen will likely not be able to explain his own paradox.
Cohen has not accepted the fact that it may be impossible to explain Cohen's Paradox in definitive analytical terms with his existing data because it is not always possible to identify empirical sources of ecologic bias from aggregate (ecologic) data alone (Field et al. 1998a)."  Ref: http://www.lww.com/health_physics/0017-90789-99ltrs.html

Let's first start with a valid formula that factors in smoking duration and intensity.  As I have suggested perhaps this information can be obtained using the methods in Gutrie's paper.  I favor thinking about ways to improve the validity of his formula and available data he has for his analysis rather than trying to explain the fruits of an unsupportable formula.

Regards, Bill Field







Information on the Burlington Health Study:
http://www.public-health.uiowa.edu/baecps/

******************************
R. William Field, Ph.D.
College of Public Health
Research Scientist - Department of Epidemiology
Adjunct Professor - Department of Occupational and Environmental Health
Graduate Faculty - College of Public Health
N222 Oakdale Hall
University of Iowa
Iowa City, Iowa 52242

319-335-4413 (phone)
319-335-4748 (fax)
mailto:bill-field@uiowa.edu
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