Dear gPPI users, 

I need a help to do gPPI comparing sessions with different conditions. I found that someone replied that gPPI allows to compare conditions in different sessions but there was no instruction how it works. When I put my conditions for comparison in P.Tasks={'0' 'TT2_in' 'TT2_out' } like this, error "Estimation Failed PPI Contrasts were not estimated for some reason." was shown. 

Is there anyone who knows how to handle this problem or is there anything that I should be careful to compare conditions in different sessions? 

Thank you in advance. 

Pyungwon

Hi,Pyungwon
    There is my way:
    I had done the PPI across the sessions, got the SPM.mat.
    Then I set the contrast within each session using Contrast Manager in the SPM batch.

Hi Pyungwon,

The error message suggests that something is wrong with the model estimation step. Are your tasks called: 'TT2_in' and 'TT2_out'?

To compare between sessions, you can use the prefix field. 

P.Contrasts.Prefix.Left={'Sn(1)'}
P.Contrasts.Prefix.Right={'Sn(2)'}

This would compare the Tasks specified in P.Contrasts.L and P.Contrasts.R between Sessions 1 and 2. If you want to compare the same condition across runs, simple use the same task in P.Contrasts.L and P.Contrasts.R.

-Donald