Dear Nádia,
probably you have a very old version of the CAT12 manual. In newer versions this contrast is mentioned on page 46:
http://www.neuro.uni-jena.de/cat12/CAT12-Manual.pdf
However, see the note: " This contrast may artificially inflate your results. More information about that issue can be found here:
https://doi.org/10.3389/fnins.2019.00352" There are many comments from Martyn McFarquhar about this topic in the maillist.
Best,
Christian
On Thu, 20 May 2021 17:33:24 +0100, Nádia Canário <[log in to unmask]> wrote:
>Hi all
>
>I'm doing a VBM longitudinal data analysis in two groups with two time points. I followed the cat12 tutorial regarding longitudinal data in two groups and i have done the F test to explore a main effect of group using the contrast suggested in the tutorial.
>
>Now i'm trying to compare one group against the other using both time points (t test) but the tutorial does not provide a contrast for that. I tried 1 1 -1 -1 but cat12 doesn't accept this contrast as valid one.
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>Do you have any suggestion how to do this?
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>Thank you
>
>Nádia Canário
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