Re: Re: Cohen's Fallacy

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

On Mon, 28 Jan 2002, Kai Kaletsch wrote:



> Understanding the mechanism helps you fill in gaps in the data. Suppose that

> the relationship: "smokers have 0.9 times the radon concentration of

> non-smokers" is based mainly on screening measurements performed in

> basements. If you don't care about the "why", you might be tempted to

> conclude that this can be translated directly into an exposure relationship.



	--The 0.9 applies separately to basement measurements and to

living area measurements, and in both cases, to various areas of the

country. See my paper in Health Physics 60:631ff;1991 which also contains

info on other matters discussed in this message.

>

> If they came out and said: "In low radon counties, all the old people live

> in high radon homes and all the young people live in apartments. That's why

> low radon counties have a high lung cancer mortality."  I would be

> satisfied.



	--The issue of apartment buildings having lower radon than

separate houses was investigated rather thoroughly in our studies. Among

the variables studied were units in structure = 1, 2, 3 or 4, 5-9, 10-19,

20-49, >50.



>

> We should note that the cross level bias needs TWO systematic associations

> to make any difference: 1) "the old people live in high radon homes and the

> young people live in apartments" and 2) "This process is inversely

> proportional to average county radon level". That is why I think the cross

> level bias theory is fairly unlikely.



	--In my experience, old people tend to live in apartments and

young people tend to live in separate homes



	--It would be fairly easy to calculate the correlations necessary

to explain my results. I am sure they would be completely implausible if

not impossible. The fraction of dwellings in buildings with >4 units is

less than 5% in half of all counties.



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line. You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/