Hello,
I have done an fmri study with 20 patients and 20 controls, and want to compare two levels (A and B) of a single factor between groups. I have tried t-tests but would like to use a within subjects ANOVA to get a non-directional contrast between the two levels.
As a first step I would like to do this just in control subjects - so a simple one-way within subjects ANOVA. Please could I ask for some advice as I am struggling to understand how to use the second level GUI in SPM8 and can't find any documentation to help explain it.
I understand that I need to specify scans and conditions. Am I right in thinking that the scans would be con.img files from the first level for each subject where the contrast is just the single level A or B - so two files per subject? If this is correct, what do I then need to enter for the condition per subject? It asks for an X by X evaluated statement but I have tried the 2x2 identity matrix and the batch failed to run.
More generally, does anyone know of a manual or set of instructions for using the SPM second level GUI - my next step will be to try this for the between groups effect as well and I'm not sure how to do this either.
Thanks so much,
Jane.
Dr Jane Garrison
Director of Studies, Psychological and Behavioural Sciences
Robinson College, University of Cambridge
