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Dear SPM users,
       I have met some problems during the process of VBM analysis.I
followed the steps in following link:
http://www.fil.ion.ucl.ac.uk/~john/misc/VBMclass10.pdf

First few steps are ok, I applied  "New segment"->"Run dartel"->"Normalise
to MNI Space" on T1 image of every case that I'm going to analyze,
including the nomal people(control) and patients.

However, while I was trying the next statistical analysis step, I met some
problems:

1. VBM analysis is a comparison of two populations of subjects, then when I
set the "Design" column as "Multiple regression" in Basic Models batch, how
do I select the files("smwc1" files) in the "scan" column to let the
program know that which subject is belong to control group or to patient
group?

p.s there more than two subjects

2.I have tried to use only two subjects in "design" column, and in "Global
Calculation" column I used the following code to obtain the volume of c1,
c2, c3 images then sum all of them to get the "Total intracranial volume"
of each subject:

V = spm_vol(spm_select(Inf,'Image'));
Vols = zeros(numel(V),1);
for j=1:numel(V),
    tot = 0;
    for i=1:V(1).dim(3),
            img = spm_slice_vol(V(j),spm_matrix(...
                  [0 0 i]),V(j).dim(1:2),0);
            img = img(isfinite(img)); % <-- exclude non-finite values
            tot = tot + sum(img(:));
    end;
    voxvol = abs(det(V(j).mat))/100^3; % volume of a voxel, in litres
    Vols(j) = tot*voxvol;
end

The details of the setting can see in the attached file "Basic Model". In
short ,after I set up all the options in the batch and finish running, the
design box pop out successfully and the SPM.mat file has been generated,
too.
But the error occurred while I used the "Estimate" button to analyze
SPM.mat file, details as attached file "error".

Is there any problems within the whole procedure I have done? Anyone can
help me with some solutions or ideas? thanks a lot!!

by GPlin