"Jason Osborne, Ph.D." wrote:
>
> I am working on a power analysis project- we are reviewing old journal
> articles to calculate observed effect sizes and power. Some of these
> articles, for example reporting t-test results, only give means and
> t-test, no standard deviation. thus, no effect size calculation is
> possible. I was hoping to estimate an effect size by converting a t to
> an r. I seem to remember a formula that relates the two, but am having
> a dickens of a time tracking one down. The one I did track down, for
> calculating t from r, is not that helpful:
>
> t= r * sqrt(n-2)
> -------------
> sqrt(1-r^2)
>
> I want to be able to calculate r from t. I tried algebraically
> manipulating the formula, but never quite got it to where I could do
> this. Any advice?
>
Try squaring both sides and re-arranging.
Bob
--
Bob O'Hara
Metapopulation Research Group
Division of Population Biology
Department of Ecology and Systematics
PO Box 17 (Arkadiankatu 7)
FIN-00014 University of Helsinki
Finland
tel: +358 9 191 7382 fax: +358 9 191 7301
email: [EMAIL PROTECTED]
To induce catatonia, visit:
http://www.helsinki.fi/science/metapop/
I have yet to see any problem, however complicated, which, when you
looked at it in the right way, did not become still more complicated. -
Poul Anderson
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