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Re[2]: The Friendly Atom

     Depends on one's frame of reference, and how real the examples are.  
     10% chance of rain is certainly real, and still suggests no rain.  10% 
     chance of car theft wouldn't occur so much in a parking lot as on a 
     street, and yes I have taken that chance, and I know cars that haven't 
     survived it. A 10% chance does not mean that every tenth car is 
     vandalized, any more than a 50% chance of tossing heads means that 
     every other coin toss is heads.  This is exactly the common 
     misperception about cancer: probability is equated to a frequency.
     I would certainly take a 95% chance that a terrorist would not attack 
     me.  Anyway,as above , a 5% probability is not a 5% certainty: one 
     person of every twenty is not certain to be attacked.
     Yes I would unhesitatingly swim in waters where there is a 0.1% 
     probability of shark attack.  I have trouble distinguishing 
     intuitively between a 0.1% risk and "no risk," and certainly can't 
     distinguish intuitively between 0.1% and 0.01%, and I suspect most 
     others can't make that intuitive distinction either. 
     One aspect of all this that I am indeed remiss in not mentioning: all 
     of the risks we have mentioned have a benefit side.  The problem with 
     radiologically associated risks is that, except for personal things 
     like x-rays, people do not see the corresponding benefit.
     By the way, here is a true story: my husband had a squamous cell skin 
     cancer removed from his arm. The probability of recovery is 95% and he 
     has fully recovered.  Our late Congressman, Steve Schiff, was one of 
     the 5% who did not recover from exactly this type of cancer, and died 
     a few weeks ago.  So even though 95% recovery still means recovery to 
     me, I recognize that 5% is significant.  It is, however, 50 times 
      Clearly only my own opinion
     Ruth F. Weiner
     Transportation Systems Department
     Sandia National Laboratories
     fax 505-844-0244

______________________________ Reply Separator _________________________________
Subject: Re: The Friendly Atom
Author:  lambert@auhs.edu at hubsmtp
Date:    4/14/98 3:00 PM

On 14 Apr 98 at 15:07, Ruth Weiner wrote:
>      The
>      perspective I suggest is that a risk <0.001 is essentially
>      intuitively zero: e.g., if the weather man predicts 10% chance 
>      of rain, do you think it's going to rain?  No.  If you have a
>      disease with a 95% recovery rate, do you think you are going to 
>      get well?  Of course.
Would you go shopping in an area where 1 out of 10 cars in the 
parking lot were stolen?  Even though the chances are that they 
would not take your car, given a choice you would probably shop 
somewhere else. Would you take a trip to a foreign land if only 95 
out of each hundred people that made the trip survived terrorist 
attacks? No, another vacation location would be selected.  Would you 
go swimming at the shore (that's what they call the beach in the 
northeast) if 1 in a 1000 (0.001) swimmers were attacked by sharks 
(that would be maybe 50 mutilated bodies per weekend along the NJ 
shore)?  I doubt it, even though the shark would probably find 
someone else more tasty.
I suggest that the severity of the outcome affects whether a risk 
of 0.1% is intuitively zero.
Kent N. Lambert, M.S., CHP
Allegheny University of the Health Sciences 
Hahnemann Division
Radiation Physics and Safety, MS 106 
Broad and Vine Streets
Philadelphia, PA  19102-1192
215-762-8768 (voice)
215-762-7683 (fax)