Hi David,
Apologies for the delay in replying.
The weighting that is effectively applied to each subject is not
currently stored in the feat stats directory. It is a function of:
S: the lower-level variance (var_filtered_func_data in the feat dir)
beta: the non-outlier random-effects variance
(mean_outlier_random_effects_var1 in the stats dir)
beta_outlier: the additional random-effects variance for outliers
(mean_random_effects_var1 in the stats dir),
probout: the probability of being an outlier (prob_outlier1 in the
stats dir)
Note that the 1's in the file names indexes the variance group. Then:
weighting(i) = 1/(sqrt(A(i))
where A(i)=(beta(i)+S(i))*(1-probout)^2 +(beta(i)+beta_outlier(i)
+S(i))*probout.^2;
and i indexes the subject.
We'll have a think about perhaps putting this in as an output in a
future release.
Hope that helps.
Cheers, Mark.
----
Dr Mark Woolrich
EPSRC Advanced Research Fellow University Research Lecturer
Oxford University Centre for Functional MRI of the Brain (FMRIB),
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
Tel: (+44)1865-222782 Homepage: http://www.fmrib.ox.ac.uk/~woolrich
On 2 Jun 2009, at 17:27, David Paulsen wrote:
> Hi,
>
> I see two output files listed in the manual: prob_outlier1.nii.gz &
> global_prob_outlier1.nii.gz. However, neither of these files answer
> the
> question concerning the precise weight given to each subject's
> voxels for
> the third level.
>
> Thanks again,
> David
>
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