Dear SPMers,
I'm a newcomer when it comes to fMRI data analysis and I wonder if I could get some help from the experts.
Currently I'm analyzing data from an event-related paradigm. I currently have 2 groups (controls vs patients) and 9 conditions + null events. In my design matrix I included all the conditions, the null events and the motion parameters. For the second level analysis I divided the conditions in two factors (3 + 6) and I will run a separate flexible factorial design for each of them in order to investigate group-condition interactions. Both flexible factorial designs will include subject, group and condition factors so that subject, group, condition, and group*condition effects are modelled. From what I read in this mailing list and papers, this seems to be the right way to do it. Am I right?
To test for differences in condition 1 between groups, I will use two-sample t-tests. In this test should I use as inputs the simple contrasts of cond1 (e.g. 1 0 0 0 0 0) from the first level analysis or should I perform a cond1 - null contrast (e.g. 1 0 0 0 0 0 -1) in the first level analysis and input these contrasts since I modelled the null events? Sorry if this is a basic question. I know that in differential contrasts between conditions this isn't a problem but this isn't the case.
Thank you all in advance,
Best Regards,
Paulo Marques.
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