RE: Risks of low level radiation - New Scientist Article

[BERNARD L COHEN <blc+@PITT.EDU>]

On Fri, 7 Dec 2001, Jim Nelson wrote:



> I diasagree totally with what you wrote below. What you are saying below is

> that smoking is not an important factor for lung cancer.



	--I said nothing of the kind. I said that if all counties studied

had very nearly the same smoking prevalence, the variations in the data

due to these very small differences in smoking would be very small.



 You really think

> "ethnic variations, medical services, reporting variations, chemicals in the

> environment and in the food,respiratory illness, etc, and just plain

> statistical variations" cause prclude a good correlation between smoking and

> lung cancer for the counties?



	--No. They do not interfere with the correlation. But they still

cause variations in cancer rates which are larger than those caused by

smoking differences because the smoking differences are very small. Hence,

they lead to a very small R-squared



  The number of standard deviations are not

> important.



	--They are a direct measure of how lung cancer rates depend on

smoking. What else is important?



  What is important is that the smoking rates for counties are

> actually predictive of the lung cancer rates for those counties.



	--If the smoking prevalence for all counties is nearly the same,

other small factors that differ much more would dominate the variations in

lung cancer.





 I also note there is a huge unexplained inverse

> relationship between your radon measurments and the smoking rates for the

> counties.  While I would like to know the reason for this inverse relation,

> it is obvious that by not using good smoking exposure data, you are left

> wwith residual condfounding from smoking to explain your finding.



	--The inverse correlation between smoking and radon is easily

explainable, but that is irrelevant. That inverse correlation reduces the

discrepancy between my data and LNT predictions. If there were no

correlation between radon and smoking, the discrepancy I found would be

still larger.



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