Dear spm's users, I found I would get different results if I did two-sample t test within a selected ROI in these two ways: 1. I did two-simple T test on 2 groups of volumetric(2/3D image) data within a spceified ROI by applying a explicit mask(such as prefrontal cortex, come from wfu_pickaltals) in "specify 2nd level" section, and then "Estimate" and "Results"; 2. I did the same two-simple T test but without applying any explicit masks in "specify 2nd level" section, but did a ROI analysis in "Results" section. I found these two different ways would lead to different results. Anybody has any suggestions on this issue? Thank you! Best regards! -- Haoran LI (MS) Brain Imaging Lab, Research Center for Learning Science, Southeast University 2 Si Pai Lou , Nanjing, 210096, P.R.China