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Hi - we use connected-components clustering: 1) threshold the Z-stat image at the specified Z threshold level (ie zero anything under this level). 2) Find connected-component clusters (where connection is allowed in 3D for any of a voxel's 26 neighbours). 3) Test each cluster's size against the size threshold derived from standard Gaussian-random-field theory using the P-threshold set by the user. The code can be seen in fsl/stable-src/cluster/cluster.cc Hope this answers the question! Thanks, Steve. On Mon, 5 Aug 2002, TetsuoKoyama wrote: > Dear > > I would like to ask you a simple question. > > I would like to know what the clustering algorithm is used for FEAR > analysis? > > Looking forward to hearing from you. > > Regards, > > Tetsuo > ---- > Tetsuo Koyama, MD, PhD > Department of Neurobiology and Anatomy > Wake Forest University School of Medicine > Winston-Salem, 27157-1010, NC > TEL: 336-716-9302 or 4284 > FAX: 336-716-4534 > E-mail: [log in to unmask] > Stephen M. Smith Head of Image Analysis, FMRIB Oxford University Centre for Functional MRI of the Brain John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve