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RE: Objectivity
Dr. Cohen,
I thought such publications already existed? For example:
Brian J. Smith, R. William Field, and Charles F. Lynch
Title: Residential 222Rn Exposure and Lung Cancer: Testing the Linear
No-Threshold Theory with Ecologic Data
Health Physics, 75(1):11-17; 1998
Abstract: In most rigorous epidemiologic studies, such as casecontrol and
cohort studies, the basic unit of analysis is the individual. Each
individual is classified in terms of exposure and disease status. However,
in ecologic epidemiologic studies, the unit of analysis is some aggregate
group of individuals. Summary measures of exposure and disease frequency are
obtained for each aggregate, and the analyses focus on determining whether
or not the aggregates with high levels of exposure also display high disease
rates. The ecologic study design has major limitations, including ecologic
confounding and cross level bias. Cohen has attempted to circumvent these
limitations by invoking the linear no-threshold theory of radiation
carcinogenesis to derive aggregate "exposures" from individual-level
associations. He asserts that, "while an ecologic study cannot determine
whether radon causes lung cancer, it can test the validity of a linear-no
threshold relationship between them." Cohen compares his testing of the
linear no-threshold relationship between radon exposure and lung cancer to
the practice of estimating the number of deaths from the person-rem
collective dose, dividing the person-rem by the number of individuals in the
population to derive the individual average dose, and then determining
individual average risk by dividing the number of deaths by the number of
individuals in the population. We show that Cohen's erroneous assumptions
concerning occupancy rates and smoking effects result in the use of the
wrong model to test the linear no-threshold theory. Because of these
assumptions, the ecologic confounding and cross level bias associated with
Cohen's model invalidate his findings. Furthermore, when more recent Iowa
county lung cancer incidence rates are regressed on Cohen's mean radon
levels, the reported large negative associations between radon exposure and
lung cancer are no longer obtained.
Again, Jim we know how you feel, so please do not download a bunch of
abstracts.
-- John
John Jacobus, MS
Certified Health Physicist
3050 Traymore Lane
Bowie, MD 20715-2024
E-mail: jenday1@email.msn.com (H)
-----Original Message-----
From: e [mailto:blc+@pitt.edu]
Sent: Wednesday, January 16, 2002 11:02 AM
To: Jacobus, John (OD/ORS)
Cc: radsafe@list.vanderbilt.edu
Subject: RE: Objectivity
On Tue, 15 Jan 2002, Jacobus, John (OD/ORS) wrote:
> Howard,
> Since Dr. Cohen would be the judge of whether he was wrong or not, I
wonder
> if it was a fair contest.
--I can't remember the details of the reward offers I made in the
past, but I thought I always incorporated some method of decision beyond
my personal judgement. My present offer surely is fair: all that is
necessary is for the person with the explanation to get it accepted for
publication in Health Physics or an equivalent journal, and they get a
$1000 reward. I have no control whatever over the process.
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