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re: st: tests of sphericity

From   David Airey <[email protected]>
To   [email protected]
Subject   re: st: tests of sphericity
Date   Wed, 1 Oct 2003 19:11:38 -0500

--- David Airey <[email protected]> wrote:
> One text on my desk mentions "Mauchly's test of
> sphericity", but I
> think the epsilon corrections are supposed to be
> preferable if you are
> going to live dangerously and use univariate
> repeated measures ANOVA.

I have no choice but to use univariate repeated
measures ANOVA. I have to many measurements and too
few subjects for a MANOVA.

My understanding is that the epsilon corrects for the
sphericity in the data but is not necessary to use it
if the data meets the sphericity assumption (i.e.
passes Mauchly's test). In which case we can use the
uncorrected F test. I do not like adjusting the df
unless it is necessary.

Thank you,
I think you are right and that nobody has written a program for Mauchley's test of sphericity. The test is available in other statistical packages. In searching a little I did not find a readable account on what Mauchly's test actually does or how I might program it myself. Do you know the original reference?

Here is a link on the topic I did come across, which I found readable.


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