AW: [ RadSafe ] Excess relative risk

Bernard L. Cohen blc+ at
Wed Feb 13 10:13:59 CST 2008

John Jacobus wrote:
> Dr. Cohen,
> So how should we view your often quoted epidemiologica studies?  I 
> have read your papers a number of times and am impressed with your 
> work.  Nevertheless, not being an epidemilogist, I would really like 
> to know how did you treat all the confounding factors in your studies 
> if not by regression analysis?  that if you think regression analysis 
> is risky what other methods are there? 
    My treatment of confounding factors is described and justified in 
great detail in my paper in  Dose-Respoinse 3: 369-390; 2005. I teat 
them by what I call "stratification" and in that paper, I show that it 
has important advantages over multiple regression analysis. I did not 
mean to demean multiple regression analysis, but I must say I am 
uncomfortable in the way some epidemiologists use it to say they have 
"adjusted for" confounding with an attitude that it is an "air-tight" 
procedure for adjusting, leaving no room for questioning or 
uncertainty.I think they should recognize that it is an imperfect 
> As a reader of history, I think that quantum mechanics and relativity 
> would have been formulated within the Twenty Century.  While Lord 
> Kelvin may have prounced that there was nothing to discover in 
> physics, it was obvious that the Planck's explanations of blackbody 
> radiation in 1900 lead to Einstein's paper on the photoelectric effect 
> in 1905. There was a problem that needed to be solved.  It is also 
> clear that Lorentz was close to discovering special relativity.  If 
> not him, then certainly someone else.
> */"Bernard L. Cohen" <blc+ at>/* wrote:
>     I hope this does not sound too radical: In my experience,
>     epidemiologists are not *scientists* in the broad sense of that term.
>     They practice a *technology* which has been "boxed" and they are not
>     willing to think outside that box. For any new ideas or
>     approaches, it
>     is "their way or the highway"; they reject them with only the
>     shallowest
>     reasoning, or more commonly ignore them. That is not the way
>     scientists
>     have traditionally operated. If physicists operated that way, we
>     would
>     never have had quantum theory, relativity, or any of the many great
>     advances of 20th century physics.
>     Their box has been successful in many applications, but it is prone
>     to failure where statistics are marginal or where there can be
>     multiple
>     confounding factors. They customarily treat the latter with multiple
>     regression analysis which is fraught with dangers -- they call this
>     "adjusting for confounding factors", factors they select with
>     something
>     less than air-tight reasoning.
>     If 2 or 3 epidemiologists take a position, a "consensus" forms
>     without those who constitute the consensus spending any time or
>     thought
>     on the subject. They just don't like to think outside their box. They
>     seem to have no experience in doing that.
>     John Jacobus wrote:
>     > One of the purposes of a skeptic is not so much to challenge as
>     to present what is unknown.
>     >
>     > I have been accussed of being silent. I am not an
>     epidemiologist, so I have to relie on those who are recognized
>     experts. (If you choose to ignore the conclusion of experts, that
>     is your choice.) The consensus has been that there are no
>     demonstracted effects below 100 mSv. Neither harmful or
>     beneficial. All studies are individual pieces of a puzzle. To
>     date, the well-known epidemiologists have reached the conclusion
>     stated above. Individual studies may support your position or
>     mine, but the concensus has always remained the same.
>     >
>     > Your uncited comments below are interesting, but how do they fit
>     in the overall study of radiation effects? I have seen some
>     studies that do show negative slopes. We can all cherry pick the
>     data that supports our positions, but what do the experts say?
>     >
>     >
>     >
>     > Rainer.Facius at wrote:
>     > "Of course, there is no proof of negative excess risk."
>     >
>     > 
> +++++++++++++++++++
> "If history teaches any lesson it is that no nation has an inherent 
> right to greatness. Greatness has to be earned and continually re-earned."
> - Norman Augustine, Chairman of the National Academies Committee
> -- John
> John Jacobus, MS
> Certified Health Physicist
> e-mail: crispy_bird at
> ------------------------------------------------------------------------
> Never miss a thing. Make Yahoo your homepage. 
> <*> 

Bernard L. Cohen
Physics Dept., University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245  Fax: (412)624-9163
e-mail: blc at  web site:

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