Sphericity test not performed due to insufficient error degrees of freedom

ClassMegalodon6 — Thu, 14 Dec 2023 10:54:24 GMT

Hi,

I have Heart rates from 3 different groups collected at 7 times differents points. I would like to perform a repeated measures ANOVA. To do so, I would like to check sphericity assumption. I found online that you have to split your data and then Analyze > fit model, I add my 7 times in "Y" then Group in "Construct model effects", then Personality "Manova", Run. I checked “Univariate Tests Also” checkbox then choose Response > Repeated Measures. At this times I have a error message "Sphericity test not performed due to insufficient error degrees of freedom" and I don't know what it means, what was the problem and how to solve it. I have n=8 in group 1(with 3 subjects who died before the end of the experiment), n=6 in group 3 (with 1 dead), and n=5 in group 2. I though it was because of the missing values but I have the same problem even if I delete lines of the dead subjects. Do you know what I am doing wrong ?

Thank you, my file is attached

PS : I had already look at the disccusion here https://community.jmp.com/t5/Discussions/MANOVA-Error-quot-Note-Sphericity-test-not-performed-due-to/m-p/56298#M31606 but it didn't help.

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Sphericity test not performed due to insufficient error degrees of freedom