Hi SPM-xperts,
I'm sure that this issue has been beaten to death but I'm still relatively new at this and haven't found the answer in a way that makes sense to me, so I will put it out there. I have run VBM analysis using CAT12 (default settings). I have run my models and found a significant group-wise difference in a cluster after TFCE, which I have saved as a nifti. I now wish to correlate this cluster with a behavioral measure in R. To do so, I need to extract the participant values. I want to make sure I do this in a way that is correct and which I can reasonably interpret/report/write about. So...
1. If I use REX or MarsBar to extract the mean value in the cluster, what images should I extract on? I would assume the modulated, unsmoothed (mwp1) images.
2. Once I do that, what are the values actually telling me? I know it's not the volume, as it is in units less than 1. To convert this to a volume, do I just need the volume of the mask multiplied by the value for each participant in the cluster?
Thanks in advance. I appreciate it.
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