Re: Radon and Smoking

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

On Wed, 13 Feb 2002, Field, R. William wrote:



> Dr. Cohen,

>

> As I have stated before, validity of findings is not a matter of numbers.

> While I do not agree with all of NCRP No. 136, I do agree with the

> following quote from NCRP concerning the limitations of ecologic studies:

>

> "Use of large numbers of geographic regions will not do away with

> biases.  More observations will generally increase precision but have

> little or no impact on validity, i.e., the degree of bias."  In other other

> words the observation can be precisely wrong.



	--I have never claimed that good statistics eliminates bias; the

two have nothing to do with each other.



>

> What I find interesting is this quote in your 1991 paper:

>

> "The results in Tables 2 and 3 clearly indicate that households with

> cigarette smokers have substantial lower Rn levels then others, but for

> some strange reason it seems that the difference decreases with increasing

> number of cigarette smoked.  It should be noted that from those tables that

> only 17% of all people who purchased Rn measurements have smoked in their

> households, whereas 33% of American adults are smokers."



	--It is not clear to me what you are trying to prove here. But an

over-riding consideration is that nothing in my analyses depends on this

difference in average radon levels for smokers and non-smokers. The ratio

of these could be anywhere from 0.3 to 2.5 without significantly changing

my results; see Table 1 of my paper in Health Physics 75:18-22;1998



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

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/