Re: Pursuit of Excellence

["Sandy Perle" <sandyfl@EARTHLINK.NET>]

On 11 Sep 2002 at 9:10, William Prestwich wrote:



> For example if you

> study the average quarterly exposures and you find they are decreasing

> during the year after a taring session given at the beginning, you might

> feel you are doing something right. 



The above may be accurate, but then again, it may not be.



One must also look at the total variation within the population. Do 

not simply look at only the average. To play with the "average" 

statistics, one only needs to insert more individuals into the 

population, which have lower to no dose, and, the average will fall. 

However, those who continually receive higher dose, may still be 

receiving the same higher dose. Looking at the average may give a 

false impression that things are improving, but without looking at 

all of the statistics, no change may have actually taken place.



Therefore, look at the average, the variance, the range, min and max, 

and to go further, simply plot the histograms, and, if you want to be 

adventurous, to see if there really is a change, initiate a t-test 

and f-test, and then you will have valid proof that the population 

dose has in fact changed.

-------------------------------------------------

Sandy Perle

Director, Technical

ICN Worldwide Dosimetry Service

ICN Plaza, 3300 Hyland Avenue

Costa Mesa, CA 92626



Tel:(714) 545-0100 / (800) 548-5100  Extension 2306

Fax:(714) 668-3149



E-Mail: sandyfl@earthlink.net

E-Mail: sperle@icnpharm.com



Personal Website: http://sandy-travels.com/

ICN Worldwide Dosimetry Website: http://www.dosimetry.com/



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