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Dear list users, I have a question regarding the correction for multiple comparisons: I compared two groups of subjects (healthy controls n =12/ mild cognitive impairment n=12) regarding their grey matter volumes with a two-sample t-test using vbm. When I correct for multiple comparisons using FDR = 0,05 I get an MIP plot with many significant regions (I chose extended threshold = 0). If I choose FWE = 0,05 for the correction of multiple comparisons, the MIP plot just contains one very small significant region in the temporal lobe. Since my sample is very small (just 24 subjects), I have the feeling that the FDR corrected results could be wrong. Isn`t it unusual to get so many signifcant regions with such a small sample? Would you use FWE or FDR in order to correct for multiple comparisons in this kind of study? Thank you for your help! Silke Matura Brain Imaging Center Frankfurt -- Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer