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Dear Ariadna, I think they are some issues here My questions are: a) FWEp would be then different for each small volume. Is this okay? FWE based on Gaussian fields is using the topology of A map to compute corrections - now if you do several SVC you use different maps but in reality related to each other; so your FWE type 1 error will increase -- this is the same as doing many tests without correcting in a way. What I would suggest, is the create a mask of all regions of interest at once (but the mask cannot come from the same data or contrast, if based on the same data, the contrast used to make the regions must e orthogonal to the one tested see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841687/) and apply this either during estimation or while checking results. see http://imaging.mrc-cbu.cam.ac.uk/imaging/SmallVolumeCorrection for a good overview b) How would you describe this procedure in the method section? c) At the peak-level, Pfwe-corr=0.03. How should I report this result? “Small volume correction analysis revealed a significant activation pFWE= 0.03 OR pSVC= 0.03?” this is Small volume correction analysis revealed a significant activation pFWE= 0.03 since RFT is used Cyril > Dear all, I followed the procedure described here in order to do small volume correction (https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1609&L=spm&P=R9957&1=spm&9=A&I=-3&J=on&X=B7BEC341E8A293F825&Y=ariadna.albajara%40gmail.com&d=No+Match%3BMatch%3BMatches&z=4) > and I would have a few questions: > > (1) I selected the constrast, p value adjustment to control: “none”, threshold: “0.001”; extent threshold: 0. > (2) I defined my small volume. > (3) I looked at FWEp at the bottom up the results table. In my case FWEp: 4.963. > (4)I reloaded the contrast, p value adjustment to control: “none”, threshold: “4.963”; extent threshold: 0. > (5)I defined my small volume like in (2) and found that at the peak-level: Pfwe-corr=0.030. > Is this alright? > > My questions are: > a) FWEp would be then different for each small volume. Is this okay? > b) How would you describe this procedure in the method section? > c) At the peak-level, Pfwe-corr=0.03. How should I report this result? “Small volume correction analysis revealed a significant activation pFWE= 0.03 OR pSVC= 0.03?” > > Thank you in advance, -- Dr Cyril Pernet, Senior Academic Fellow Neuroimaging Sciences Centre for Clinical Brain Sciences Chancellor's Building, Room GU426D The University of Edinburgh 49 Little France Crescent Edinburgh BioQuarter EH16 4SB [log in to unmask] tel: +44 (0)131 465 9530 http://www.sbirc.ed.ac.uk/cyril http://www.ed.ac.uk/edinburgh-imaging The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.