Posted by
Mike on
Mar 23, 2011; 1:33am
URL: http://spssx-discussion.165.s1.nabble.com/Mauchly-s-sphericity-test-tp4258003p4258057.html
Mauchley's test is inappropriate for a within-subject design with only
two time points/repeated measures. Sphericity is automatically met
in this condition. Jason Newsom explain this point in his notes for his
graduate data analysis class; see:
http://www.upa.pdx.edu/IOA/newsom/da1/ho_wsassump.pdfIn the SPSS repeated measures ANOVA there are several results
that are output which most people will routinely ignore if all they
want is a simple repeated measures ANOVA, results such as
Multivariate results and polynomial contrasts for within-subject
factors that purely categorical (i.e., they should only be used if
the levels of the within-subject factor can be order, best on a ratio
scale and not a factor such as different categories of words/stimuli).
Historically, SPSS came late to doing repeated measures ANOVA
and still make these types of "errors" when (1) is should know
whether the Mauchley test is relevant or not and omit it if it is
irrelevant, (2) have the analyst request multivariate results if they
want it, and (3) have the analyst request polynomial tests for
within-subject factors.
So, the Mauchley test results should be ignored, as should the
corrections in the ANOVA table for the within-subject factor
(why does SPSS print 3 additional lines of exactly the same
numbers???).
-Mike Palij
New York University
[hidden email]
----- Original Message -----
From: "la_kennedy" <
[hidden email]>
To: <
[hidden email]>
Sent: Tuesday, March 22, 2011 8:41 PM
Subject: Mauchly's sphericity test
> Hey,
> I am running analysis to find how the manipulation of mood affects sporting
> performance. I have done pre and post mood manipulation tests on 2 sets of
> participants (positive and control), from this I get 6 lots of data
> (performance scores, positive mood scores, negative mood scores both pre and
> post).
> I used a repeated measures anova on spss but the sig section in the
> Mauchly's sphericity test table is empty.
> What am I doing wrong?
> Any advice would be appreciated.
> Thank you.
> with regards,
> la_kennedy
>
> --
> View this message in context:
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