Dear SPMers,
I’m trying to do a PPI analysis of an event-related design.
After clicking on the “PPIs-Button”, I specified the SPM file on single subject level and chose psychophysiologic interaction.
As physiological variable I have chosen my VOI-file I generated before.
Now I can chose which contrasts from the SPM-file, I would like to include in my PPI model.
My question is, if it makes a difference if I click “No” for a specific contrast or if I click “Yes” and set the contrast weight to 0?
Until now I couldn’t find any recommendations which is the better way for calculating a PPI model.
Is there anybody who has an idea about this issue?
Thank you and best regards
Marco
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