When doing a multi-group analysis in SPM with followup data, how do I do a
group by time interaction? I.e. I have my design matrix as:
Group 1(scan1) Group 1 (scan 2) Group2(scan 1) Group2 (scan2)
SPM will let me do contrasts within group such as [1 -1 0 0] or [0 0 -1 1]
but not contrasts across groups [1 0 -1 0], for example. What am I doing
wrong? Thanks
Chris Christian
> Hi SPMers,
>
> does anybody have a better way to introduce the contrast as typing each
> time
> each single 1, -1 and 0?? I'm starting to get crazy!!!
>
> Thanx a lot in advanced.
>
> --
> Maria de la O Olmedo Babe
>
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