Re: LNT, Collective Dose

[Bernard L Cohen <blc+@pitt.edu>]

On Thu, 22 Feb 2001, Harry Hinks wrote:

>   Assume you go out to the 
> nearest town and randomly choose 3 homes to test their radon in their 
> basement.  Again assume you get readings at the 3 houses of 24 
> pCuries/liter, 2 pCuries/liter and 1 pCuries/liter.  With summary data using 
> the collective dose assumptions, you would assume the basement concentration 
> for each individual in that town is 9 pCuries/liter, correct?  But in 
> reality, you know the basements were 24, 2 and 1.   In studies using data 
> from individual houses, you have the readings.  In summary data studies, you 
> do a poor job of measuring the actual concentrations.

	--Of course you have to collect enough data to get a true average,
and 3 houses is not enough. But aside from this, in your example, if LNT
is correct, the only thing important for determining the number of cancers
is the 9 pCi/L average. No further useful information is obtained by using
measurements in particular houses.

> Regardless if the LNT is true or not.  Summary data is not as good as 
> individual data.  Isn't it the individuals who get the lung cancer and not 
> everyone on the whole town?

	--Given your first sentence, you are wrong. If LNT is true,
summary data is just as good; this can be shown with mathematical rigor.
In saying this, I am ignoring issues of confounding variables, which
is a separate subject. Confounders can be important in any
epidemiological study and the problems they present are different in
studies of individuals than in studies using summary data. I can easily
suggest  potential confounders that could invalidate any case-control
study of radon in homes vs lung cancer. But no one can suggest a potential
confounder that could invalidate my study.

>  Why allow a few measurements to represent the 
> whole town when you can collect information on the levels at the houses 
> where the people have the lung cancer.

	--Your word "few" implies not enough to give a valid average;
obviously there must be enough to get a valid average, and I have given
abundant evidence that this was not a problem in my study.
	The very great advantage of my study over studies of individuals
(like case-control) is enormously better statistics in the low dose
region. In my study, LNT fails the test by 30 standard deviations, but no
case control study gives a test with even 2 standard deviations. Another
advantage is that a typical case-control study treats very few potential
confounders, 5 or less, whereas my study treats over 500 potential
confounding factors
	But the important point is that my test has been done, and LNT
fails, unless someone can come up with an alternative explanation. Failing
one experimental test is enough to validate a theory. Of course other
tests are always welcome.

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