power for repeated-measures ANOVA lacking sphericity

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power for repeated-measures ANOVA lacking sphericity

Yuelin Li
Is there a function that calculates the power of a
repeated-measure ANOVA design, e.g., 2 groups, 4
within-subject factors, an average 0.40 correlation between
the 4 within factors, etc.

I don't think I can use power.anova.test() because it does
not consider corr=0.40.  

I am hoping that someone has already implemented the method
by Muller & Barton (1989, JASA 84: 549-555) on how to
approximate statistical power for a univariate test in
repeated-measures ANOVAs when the sphericity assumption is
not met.  If not, perhaps the MANOVA approach by O'Brien &
Kaiser (1985, Psych Bull: 97, 316-33).  

library(pwr) does not seem to support either.  
Many thanks in advance,

Yuelin Li.

 
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Re: power for repeated-measures ANOVA lacking sphericity

Thomas Lumley-2
On Fri, Mar 11, 2011 at 6:08 AM, Yuelin Li <[hidden email]> wrote:
> Is there a function that calculates the power of a
> repeated-measure ANOVA design, e.g., 2 groups, 4
> within-subject factors, an average 0.40 correlation between
> the 4 within factors, etc.
>
> I don't think I can use power.anova.test() because it does
> not consider corr=0.40.
>

The easiest approach is likely to be simulation: simulate data from
the design and compute the p-value, repeat a few thousand times.

    -thomas

--
Thomas Lumley
Professor of Biostatistics
University of Auckland

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