R help - Jan 2006 - Unequal sample sizes when calculating power

Power calculations two sample test for proportions is very useful. Is there
a way however, to get away from the two samples being of the same size. What
would happen if one had n=15 in the one sample and n=45 in the other sample.

Farrel Buchinsky, MD 
Pediatric Otolaryngologist
Allegheny General Hospital
Pittsburgh, PA 



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Farrel Buchinsky <fbuchins at wpahs.org> writes:
> Power calculations two sample test for proportions is very useful. Is there
> a way however, to get away from the two samples being of the same size.
What
> would happen if one had n=15 in the one sample and n=45 in the other
sample.
Take a look at

https://www.stat.math.ethz.ch/pipermail/r-devel/2003-September/027458.html

That's for t-tests, but similar modifications might be used for
power.prop.test 

-- 
   O__  ---- Peter Dalgaard             ??ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907

On Wed, 2006-01-25 at 09:50 -0500, Farrel Buchinsky
wrote:
> Power calculations two sample test for proportions is very useful. Is there
> a way however, to get away from the two samples being of the same size.
What
> would happen if one had n=15 in the one sample and n=45 in the other
sample.
See ?bpower and ?bpower.sim (along with the other functions on the same
help page) in Frank Harrell's 'Hmisc' package on CRAN.

HTH,

Marc Schwartz
 
P.S. Go Steelers!  :-)