Dear Carolina,
Carolina C. wrote:
> Dear SPMers
>
> We are trying to look for differences between two groups (patients and
> controls) (PET study) with 3 conditions A (baseline), B and C (2
> different olfactory stimuli) (2 scans per condition)
>
> Chosen design type - multi-group: conditions and covariates,
>
> Input 10 patients for group 1,
>
> 21 controls (10 females and 11 males) for group 2,
>
> 3 conditions (1 for A, 2 for B and 3 for C)
>
> Covariates 0
>
> Global normalization-proportional scaling to 50
>
> Threshold masking =relative (relative to global 0.8)
>
> Global calculation – mean voxel per value (within per image full mean/8mask)
>
> Non-sphericity correction - yes
>
> Replications are over – 3 conditions
>
I think if you change this to 'subjects' you should be OK.
Each subject is a replication in the sense that each
produces a trivariate response (ie 3 responses).
There will possibly be some correlation in responses
that can be modelled by a 3 by 3 covariance matrix.
Each subject provides a `sample' or `replication' that allows SPM
to estimate this covariance.
Best,
Will.
> Correlated repeated measures – Yes
>
>
>
> And immediately after I get this message in the command window
>
>
>
> Initialising parameters :
> ...computing??? Index exceeds matrix dimensions.
>
> Error in ==> /usr/local/matlab65/toolbox/matlab/sparfun/spdiags.m
> On line 102 ==> a = [a; i i+d(k) B(i+(m>=n)*d(k),k)];
>
> Error in ==> /usr/local/spm2_updates/spm_spm.m
> On line 420 ==> s = spdiags(1./sqrt(diag(s)),0,nScan,nScan);
>
> Error in ==> /usr/local/spm2_updates/spm_spm.m
> On line 827 ==> SPM = spm_spm(SPM);
>
> Error in ==> /usr/local/spm2_updates/spm_getSPM.m
> On line 197 ==> [SPM] = spm_spm(SPM);
>
> Error in ==> /usr/local/spm2/spm_results_ui.m
> On line 260 ==> [SPM,xSPM] = spm_getSPM;
>
> ??? Error while evaluating uicontrol Callback.
>
>> >
>
>
>
> Must add, without non-sphericity correction model is accepted. I've
> tried with simplified model and got the same message.
>
>
> I would greatly appreciate some advice
>
> Kind regards
>
> Carolina
>
>
>
--
William D. Penny
Wellcome Department of Imaging Neuroscience
University College London
12 Queen Square
London WC1N 3BG
Tel: 020 7833 7475
FAX: 020 7813 1420
Email: [log in to unmask]
URL: http://www.fil.ion.ucl.ac.uk/~wpenny/
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