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st: Help with sample size.


From   "Don Spady" <dspady@ualberta.ca>
To   "Statalist" <statalist@hsphsun2.harvard.edu>
Subject   st: Help with sample size.
Date   Fri, 25 Apr 2003 13:34:21 -0400 (EDT)

Dear all
  I want to estimate the sample size needed to detect an disease that
occurs in 1 out of 1000 people (as an example).  I don't know the exact
variance but probably would assume it to be the same as the proportion
affected. (I don't know if that is appropriate or not)  The alternate
state is absence of disease which would occur in 999 of 1000 people on
average.   Can I use sampsi grp1 being those with disease and Grp2 being
those without disease.
I need help and thank in advance those that provide it.

Donald Spady
Dep't of Pediatrics, University of Alberta
(780) 407-1244

Nature has no reset button.


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