Dear Fuyu
Nice to hear from you. I hope you don't mind me CC'ing the SPM mailing list so others can benefit. (I am always happy to help, but where possible, please could I ask you to email the mailing list rather than sending direct emails with queries?)
> 1. When creating the VOI (based on peak coordinates from 2ndlevel) for individual subjects, how low can we set the uncorrected threshold to be in order to obtain the activation at the peak coordinate/ within the area?
> 2. For the T-value at the VOI, is there a minimum value that should be obtained?
You could set the uncorrected threshold to infinitely low (i.e. p = 1). The purpose of the threshold here is to select which voxels to include in the ROI, rather than performing a statistical test, which you have already done at the group level. It can be advantageous to only include voxels which show some experimental effect. Otherwise, there's an increased risk that the first principle component represents a physiological or other noise process rather than relating to the task. So there's no right answer, but how about going for p = 0.05 as your most liberal value. And then relax it further if you can't get signal from every subject.
Best
Peter
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