Dear SPMers,
In my fMRI experiment, i am using the gPPI Toolbox for my analysis.
I created a gPPI model on 1st level and specified my contrast of interest.
For 2nd level analysis, I used the con-images of each subject, which was created in the 1st level analysis.
In this 2nd level analysis I created a one sample t-test, to see the gPPI effects in this group. (I don’t do any group comparison yet)
Is this procedure correct so far?
Now I have the following question, regarding the interpretation of the 2nd level analysis:
- Is the usual way for the gPPI analysis to set a T-contrast on “1” in the 2nd level model?
- How can I interpret the gPPI model, if I set the 2nd level T-contrast on “-1”?
- Does it make sense to use an F-contrast in the gPPI model, or is the interpretation difficult, because it isn’t directional?
Thank you for your help!
Best regards
Marco
PhD Student
University of Basel
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