I performed an fMRI task for attention. Then using the 'con files' of all the subjects, I performed a multiple regression analysis in SPM8, with a behavioral score as covariate to identify the regions that have a positive or negative correlation with the score. I want to perform AlphaSim for this multiple regression analysis to find the minimum cluster size for alpha 0.05. My uncorrected p value is 0.01, slice thickness is 3 mm.
What should I input for the mask image? Can I use the 'mask' image generated during the regression analysis?
What is the cluster distance? Is it the same as slice thickness?
How to calculate the FWHM for the data? I performed the smoothing at 6mm FWHM.
Thanks and regards,
NMR research Centre,