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Yes, you can have more patients in step 3. You only need equal numbers for creation of the template. On Thu, Sep 11, 2014 at 12:09 PM, Stephen Smith <[log in to unmask]> wrote: > Hi > > On 11 Sep 2014, at 17:06, Paul Beach <[log in to unmask]> wrote: > > FSL folks, > > So the VBM wiki talks about making sure that one has equal parts controls > and patients when doing early VBM steps. I understand the rationale for > this in terms of making an unbiased template. > > However, are you supposed to always keep things like this (i.e. completely > equal, number-wise) for the entirety of the VBM analysis? > > > No - later stages are fine - e.g. a two-group t-test is unbiased by > different group sizes. > > [ If *all* stages demanded equal group sizes, we wouldn't have had to add > in the option of early stages only using subsections of the input data..... > ] > > Cheers. > > > > > > It seems like you could add back the "extra" subjects in whatever group at > step 3 and beyond. Is that correct, or are you completely limited by > whatever group has the lowest 'N'? > > Thanks > -- > Paul Beach > DO/PhD candidate - Year VI > Michigan State University > - College of Osteopathic Medicine > - Neuroscience Program > - MSU *Co*gnitive and *Ge*riatric *N*eurology *T*eam (*CoGeNT*) > > > > --------------------------------------------------------------------------- > 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 > --------------------------------------------------------------------------- > > Stop the cultural destruction of Tibet <http://smithinks.net> > > > > >