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Hi, Yes I suspect you're right that the cluster just isn't big enough to be significant. If you raise the cluster-forming threshold that _may_ help somewhat but that's no guarantee that it will reach significance. In general you get most sensitivity when the smoothing extent matches the signal extent so the comment about smoothing may possibly help. Cheers. On 1 Dec 2008, at 17:26, Hilary watson wrote: > Hi > > I was also wondering if small clusters were failing to come out in my > analysis. I ask because when I run feat query using a right > hippocampal > mask there appears to be significant voxels (as indicated by max z > value) > that don't show up when I do pre-threshold masking (using the same > rhipp > mask). I thought this may be because the cluster may be too small > for the > threshold I am using, however when I do use higher threshold this > doesn't > seem to make a difference. > > Someone recommended I reduce the width of my spatial filter.. could > this help? > > Sorry if this isn't clear. > > Hilary > --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Associate Director, Oxford University FMRIB Centre FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve ---------------------------------------------------------------------------