The error message is as follows:
Warnings Box's Test of Equality of Covariance Matrices is not computed because there are fewer than two nonsingular cell covariance matrices.
However, the results are computed anyways.
I want to know what does it actually means.
Does it affect the overall results?
How to fix this error?
It should be noted that the sample size in my groups is different.
I would appreciate your guidance.
Baset
Hello Abdulbaset,
In order for SPSS (which is what I presume you are using for analysis) to compute and report a Box M test (multivariate homogeneity of covariance matrices test, a test that is not needed if you are strictly sticking to univariate repeated measures designs), you need:
1. Two or more independent groups (e.g., at least one between-subjects factor).
2. Scores on two or more measures per case.
3. SOME variance for each measure within each group.
4. The scores must not be linearly dependent (e.g., score2 can't be a simple function of score1).
Conditions #1, #2, #3 don't impact whether a MANOVA can be executed or not; hence, you can get results (regardless of whether they are meaningful!). If condition #4 holds, SPSS will omit at least one variable from the MANOVA.
Good luck with your work!
David Morse
Dear Dr. David,
Thank you for the detailed explanation.
I see that warning message after performing a mixed repeated measures ANOVA!
Should it be taken seriously?
I have six groups with a different sample size in two of them.
- Badges
- Science topic
- Similar topics
- Mathematical Sciences
- Statistics
- Statistical Software
- SPSS