Re: Mr. Ford and Iowa Radon Lung Cancer Study

["Rad health" <healthrad@HOTMAIL.COM>]

Ted,



Think about sitting in on a class on multivariate analysis to understand the 

process.  You may be surprised.



Don



>From: Ted de Castro <tdc@xrayted.com>

>To: Rad health <healthrad@HOTMAIL.COM>

>CC: radsafe@list.vanderbilt.edu

>Subject: Re: Mr. Ford and Iowa Radon Lung Cancer Study

>Date: Fri, 25 Jan 2002 20:08:55 -0800

>

>Yes - I got the point that it was not uncommon AND I presumed it was

>done professionally and properly.  I just do not find it credible that

>it can be modeled to a high enough level of accuracy AND precision that

>the residual error from an overwhelming confounder will allow a smaller

>effect to be discerned.

>

>Rad health wrote:

> >

> > >From: Ted de Castro <tdc@XRAYTED.COM>

> > >I am having trouble with this - I don't see that it matters that the

> > >mathematical correction is a "common" or "standard" practice of

> > >"correction" - THAT claim does not speak to its precision or accuracy.

> > >I find it hard to fathom that medical science knows the relationship

> > >between smoking and lung cancer well enough to reduce it to a

> > >mathematical formula - let alone a formulation so accurate and precise

> > >that it can be used to correct an overwhelming confounder (small errors

> > >with a correction of a large number will allow large errors in the

> > >assessment of a smaller number).  It is hard to accept.

> >

> > Ted, I think the point he was making was that it is not that uncommon to 

>do

> > this in everyday practice.  It is not a matter of medical science

> > understanding it, it is a matter of whether or not smoking can be 

>modeled

> > accurately for the subjects.  This modeling can take a week or so to 

>perform

> > using standard techniques of multivariate regression.  Just because it 

>is

> > standard does not mean it was done correctly.  But looking at who the

> > statisiticians were gives me confidence it was done correctly.

> >

> > Besides they looked for residual confounding and did not find any.

> >

> > http://www.public-health.uiowa.edu/faculty/~woolson.html

> >

> > It was my understanding the retrospective recall was based on life 

>events.

> > People know when they had kids, worked, were at home, etc.

> >

> > Don

> >

> > _________________________________________________________________

> > Chat with friends online, try MSN Messenger: http://messenger.msn.com

> >

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