[R] mixed model MANCOVA

John Fox jfox at mcmaster.ca
Thu Sep 11 03:45:34 CEST 2008


Dear Erika et al.,

I'm not sure exactly what you want to do, but you might take a look at the
Anova() function in the car package, which will compute "type-II" or
"type-III" tests for multivariate linear models, including models with
repeated measures; you can also get the traditional univariate tests. Be
very careful of Type-III tests, especially if the covariate is involved in
interactions, since it's very easy to test strange hypotheses (as is true
even in a univariate context). There are some examples of repeated-measures
ANOVAs and MANOVAs in ?Anova.

I hope this helps,
  John

------------------------------
John Fox, Professor
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
web: socserv.mcmaster.ca/jfox


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
> Behalf Of hadley wickham
> Sent: September-10-08 8:53 PM
> To: Erika Crispo
> Cc: r-help at r-project.org
> Subject: Re: [R] mixed model MANCOVA
> 
> On Mon, Sep 8, 2008 at 1:06 PM, Erika Crispo
> <erika.crispo at mail.mcgill.ca> wrote:
> > Hello,
> >
> > I need to perform a mixed-model (with nesting) MANCOVA, using Type III
sums
> of squares. I know how to perform each of these types of tests
individually,
> but I am not sure if performing a mixed-model MANCOVA is possible. Please
let
> me know.
> 
> Why?  What is the purpose of your analysis?  Why do you think a
> mixed-effects MANCOVA is appropriate? What have simpler models told
> you about the data?  What exploratory graphics have you done?
> 
> Hadley
> 
> 
> --
> http://had.co.nz/
> 
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