Hi Doug,
The difference is due to the whitening stage in FILM - i.e., we're
not doing OLS here, hence the difference you're seeing I guess.
Cheers, Steve.
On 25 Apr 2007, at 00:55, Doug Greve wrote:
> Is there a way to get the residual variance from the feat output? I
> had thought it was the sigmasquareds volume, but that seems not to
> be the case. I say that because I ran feat, saved the residual, and
> computed the residual variance, and it was different than
> sigmasquareds. The residual variance was always more than
> sigmasquareds, but this ratio varied across space (see link below).
> In particular, the ratio was close to 1 in white matter, but
> sigmasquareds was somewhat less than the residual variance in gray
> matter. Is the residual variance stored somewhere else? If not, I
> can script it myself. And what is the interpretation of sigmasquares?
>
> thanks
>
> doug
>
> ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
> feat.var-ratio.gif
>
> --
> Douglas N. Greve, Ph.D.
> MGH-NMR Center
> [log in to unmask]
> Phone Number: 617-724-2358 Fax: 617-726-7422
>
> In order to help us help you, please follow the steps in:
> surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
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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
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