Re: Recommendation to resolve Cohen's ecologic study questions

[hflong@postoffice.pacbell.net]

Dear Bill,

I concede that your Iowa study is much more scientific than most medical articles

appearing in the JAMA. However, I do hold us to a higher standard: try for as

identical control matches as possible (the best being reproducable, double blind

placebo trials).



I also concede that it is very difficult to do this with radon. So I am considering

a surrugate, using the "1.3 pCi/l radon in home = about 1.6 rem x-ray/year to

bronchi " ionizing radiation effect stated by (? I can look up the reference). For

comparison, chest CT (Picker, Phillips or GE) gives an acute dose of one rem,

average.



Meantime, the above is consistent with Cohen's comment, 1/22/02

"I do not "adjust" my data for anything. I treat confounding by my method of

stratification which is very much superior."



"Field, R. William" wrote:



> Dr. Long,

>

> I am sorry to see your comments appear to becoming more frustration than

> science ?

>

> At 01:59 PM 01/24/2002 -0800, you wrote:

> >Brassy, coming from one who "adjusted" for "controls" smoking 32% when

> >cases smoked 86%!

> >

> >However, I know you will have a more positive response.

> >

> >Howard

> >

> >"Field, R. William" wrote:

> >

> > > Dr. Cohen,

> > >

> > > The explanation is simply that you have group level confounding that you

> > > have not accounted for.

> > >

> > > Smoking (among other factors) confounds your radon covariate at the

> > > regional level, but most of the smoking variability occurs within counties

> > > rather than between counties.  Therefore, as suggested in Guthrie's paper,

> > > you need county level population incidence data and covariate data from a

> > > sample survey.  As we pointed out before, in order to explain your findings

> > > you will likely need more data than is available from existing published

> > > sources.

> > >

> > > Would you like me to fax you a copy of Guthrie's paper?

> > >

> > > Bill Field

> > >

> > > At 01:08 PM 01/23/2002 -0500, you wrote:

> > >

> > > >On Tue, 22 Jan 2002, Field, R. William wrote:

> > > > >

> > > > > Here is my specific recommendation.  If you are really interested

> > in using

> > > > > your ecologic data and getting at the potential sources of your

> > bias, you

> > > > > need to identify what inter county adjustments need to be made by using

> > > > > more innovative methods.  Possibly those suggested in: Guthrie, KA and

> > > > > Sheppard, L, Overcoming biases and misconceptions in ecological

> > studies,

> > > > > J.R. Statist. Soc., volume 164, pp 141-154, 2001.

> > > >

> > > >         --Where is your specific suggestion for an explanation for my

> > > >discrepancy with LNT? I ask for a specific suggested cause, not for a

> > > >suggested procedure. I am surely entitled to any procedure I like as long

> > > >as it justifies my conclusion.

> > >

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