Re: Mauchly's sphericity test

Posted by Bruce Weaver on Mar 23, 2011; 1:23am
URL: http://spssx-discussion.165.s1.nabble.com/Mauchly-s-sphericity-test-tp4258003p4258044.html

If you mean that you run a 2x2 between-within ANOVA on each outcome variable, then there can be no lack of sphericity--it can only be a problem when you have 3 or more levels for a repeated measures factor.

Also, if you are running 2x2 ANOVAs, you might consider ANCOVA instead, with Y = post, covariate = pre, fixed factor = group (positive v control).  For experiments (with random assignment to groups), this is usually the preferred model.

HTH.

la_kennedy wrote

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