AW: [ RadSafe ] Excess relative risk

THOMAS POTTER pottert at
Wed Feb 13 09:02:11 CST 2008

I'm no epidemiologist or even a statistician, for that matter, though I've studied statistics some.  But I think Dr. Cohen's position re epidemiology is way too radical.  Epidemiologists develop hypotheses.  They design experiments to test them, taking care not to introduce serious biases into the design. They evaluate data using mathematically rigorous methods that analyze the entire data set, not just a few points that might look interesting based on potentially misleading eyeball inspection.  What's  not scientific about this approach?  Dr. Cohen's response to the Iowa grad student should have been, "How so?"

Tom Potter

Date: Tue, 12 Feb 2008 15:47:57 -0500 
From: "Bernard L. Cohen" <blc+ at> 
Subject: Re: AW: [ RadSafe ] Excess relative risk 
To: John Jacobus <crispy_bird at> 
Cc: Rainer.Facius at, radsafe at 
Message-ID: <47B205FD.7020501 at> 
Content-Type: text/plain; charset=ISO-8859-1; format=flowed 

   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.

Date: Wed, 13 Feb 2008 11:44:37 +1100 
From: "Brent Rogers" < at> 
Subject: RE: AW: [ RadSafe ] Excess relative risk 
To: "'Bernard L. Cohen'" <blc+ at>, "'John Jacobus'" 
<crispy_bird at> 
Cc: Rainer.Facius at, radsafe at 
Message-ID: <000901c86dd9$a59cb2e0$7400a8c0 at brent28417bbe6> 
Content-Type: text/plain; charset="iso-8859-1" 

Great reply, Professor Cohen.  I'm pleasantly reminded of the best rejoinder 
I ever saw on RadSafe.  One that you provided about 10 years ago, and I 
paraphrase now: 

University of Iowa epidemiology grad student:  "Your method violates 
Epidemiology 101." 

Prof Cohen:  "I am bound by the Scientific Method, not Epidemiology 101." 

I'm still waiting for the opportunity to use a similar line myself. 

Brent Rogers 

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