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Re: st: repeated measures ANOVA to MANOVA - revisit, khi


From   Philip Ender <ender97@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: repeated measures ANOVA to MANOVA - revisit, khi
Date   Fri, 3 Feb 2012 18:33:54 -0800

This is a response to Ricardo Ovaldia <ovaldia@yahoo.com> concerns
about repeated measures anova in Stata.

As a check on the analyses, I ran Ricardo's data using SPSS's repeated
measures anova.  SPSS repeated performs both multivariate and
univariate repeated measures.  The SPSS results were identical the the
results presented by Ken Higbee in
www.stata.com/statalist/archive/2012-02/msg00183.html.  The SPSS
results also had a large difference in the p-values between the
Huynh-Feldt and the multivariate results.  One reason for this is the
the univariate repeated measures and multivariate repeated measures
make different assumptions about the covariance structure of the
repeated measures.  The univariate approach assumes compound symmetry
(exchangeable) while the multivariate approach assumes that the
covariances are unstructured.  For many situations, the multivariate
approach has the less restrictive assumption at the cost of estimating
more parameters.

-- 
Phil Ender
UCLA Statistical Consulting Group
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