On Mon, 24 Mar 2008 20:32:14 -0700 (PDT), JunoExpress
<MTBrenneman@[EMAIL PROTECTED]
> wrote:
> Hi,
>
> I understand how to determine the sample size if you are doing a
> simple hypothesis test (like equality of means) with 2 populations.
>
> Recently, however, I had to undertake a one-way ANOVA test where I am
> using more than one population.
And how does "more than one" differ from the first paragraph,
where you said you understand with two populations?
Three?
> Nothing fancy, no complex design
> issues, just good old straightforward ANOVA. I have been able to find
> very little in the way of how sample size is determined, and I am
> wondering if anyone can either explain the basic concept involved or
> point me in the direction of a good text that is not too advanced
> (maybe 1st yr grad level) yet explains this problem well.
The standard social science reference is Cohen's book,
Statistical Power for the Social Sciences (1990).
With more than two groups, you have choices on how
to model the differences - one group vs. two at the other
end, or randomly ordered. The "effect size" is based on
computations resembling the F test, i.e., squared differences.
--
Rich Ulrich
http://www.pitt.edu/~wpilib/index.html
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