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that's good news then! wrt to the absolute values - yes, I've found myself that 16 "normals" that I ran came out with VSCALING averaging about 1.3, suggesting the normals had 10% (linearly) smaller heads than the MNI152. The registrations look fine, so I suspect the answer is just what it appears to be, namely that the populations we are testing are smaller than whatever absolute scaling system was used in the creation of the MNI152. Thanks, Steve. On Tue, 14 Jan 2003, Erik-Jan Vlieger wrote: > I am very, very sorry, I feel very dumb, I made a mistake: the scalingfactors > really are OK, with a kappa of 0.97. > > Sorry, > Erik-Jan Vlieger > > > I continued my analysis of the output of sienax, and found another other > > disturbing fact. > > I analyzed 80 volumes, of which 20 were left/right mirrors of 20 others. > > The gray and white matter volumes reproduce perfectly (kappa of 0.998 or > > so), but the scaling factor does not reproduce at all. Add this to the fact > > the that the scaling factors were all above 1.0 and I get the feeling that > > something is very wrong with registration to the template. > 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