Re: power program for Cohen's estimated reduction in variance technique?

On 20 Sep 2005 12:37:46 -0700, "carol" <carolf@xxxxxxxxxxxxxxxx>
wrote:

> Does anyone know of a power analysis program that will calculate power
> and sample size based on variance reduction estimates per Cohen?

I don't know what "variance reduction estimates" that would
be, but if it is by Jacob Cohen who wrote the book on
power analysis in the social sciences, have you looked
at the program that was written to do the analyses in the book?

I distrust using computer programs for power analysis,
because it is far too easy to under-define the terms.
(And for Cohen's program, be careful if you are using
an old edition of the book, because he changed a
couple of parameterizations.)


--
Rich Ulrich, wpilib@xxxxxxxx
http://www.pitt.edu/~wpilib/index.html
.