Hi all,
I'm wondering whether someone can help me with running a PPI analysis in SPM8. I have previously used SPM5 for PPI and now wish to use SPM8.
The problem that I am having is when I create the PPI terms and view the PPI.P variable, I see a pattern of numbers which differ for participants and which are interspersed with zero values at fixed intervals such that if the same run is looked at in different participants and for different contrasts, the position of the 0s will be the same... for example:
PPI.P
-0.0156
-0.0171
0
0
0
0
-0.0122
0.01131
0
0
and so on, and the zeros will feature at the same point, seemingly for the same scans for different participants and different contrasts. This didn't happen with SPM5. Does anyone have any idea what may be causing this?
I've changed the last line in spm_PEB to -16 from -32, but I also had to do this for SPM5.
Any help or info would be much appreciated.
Thanks very much,
Sophie
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