-------- Original Message -------- Subject: Re: Fwd: CVA versus MANOVA Date: Mon, 21 Mar 2011 08:03:00 -0400 From: Øyvind Hammer <[email protected]> To: <[email protected]> Hi, this is normal ... if you include a large number of variables compared with cases in the CVA, you will see a strong separation even for completely random data with no real groups. The MANOVA, on the other hand, will adjust for the number of variables, and (correctly) report non-significance. In such cases, you will see that the seemingly successful classification breaks down completely if you run a cross-validation (jack-knifing) on the CVA. A CVA should always be accompanied by a MANOVA to check that the groups are "real". Or something like that. Øyvind Hammer Natural History Museum University of Oslo
Hi, I am analyzing a dataset with 21 landmarks and 2 groups. I have run CVA on both IMP and MorphoJ and it suggests a very strong grouping. The deformation plot in IMP shows 3 areas of deformation while the MorphoJ plot doesn't show any obvious deformations on CV1 (the significant axis as displayed by IMP). However when I ran a univariate ANOVA on the centroid sizes and a MANOVA on the partial warps and relative warps with SPSS there was no significant difference between groups. I am new to this type of analysis and I was wondering if perhaps I am missing something? Any suggestions would be greatly appreciated. Thanks, Michelle
