Hi Diehl,
I've run into the same problem and have used the PET/SPECT models
options. These analyses allow for more than one co-variate in either
the "multi-group: conditions and covariates" or the "multi-subjects:
conditions and covariates" selections. I've checked the results of
these models with those of the ANCOVA in the fmri options for a single
co-variate and have gotten identical results.
Hope this helps.
-Skip
On Mar 9, 2005, at 2:12 AM, Diehl wrote:
> Dear SPM Group and John West,
>
> we are currently trying the same (ANCOVA with mutliple covariates) and
> do not get it work, too.
> Does anybody of the SPM Group have something like a manual for the
> ANCOVA procedure in SPM2???
>
>
> Thanks a lot,
>
> Alexander Diehl, MD
> Central Institute of Mental Health, Mannheim, Germany
>
> John D. West schrieb:
>
>> Dear SPM group:
>>
>> We are currently trying to setup an ANCOVA with multiple covariates
>> for VBM. Unfortunately, the basic ANCOVA in SPM2 appears to only
>> permit one covariate (as a nuisance variable).
>>
>> We could use any suggestions you might have to setup this analysis.
>>
>> The basics of the VBM analysis we wish to perform are as follows:
>> There are two between subjects factors that we wish to investigate in
>> a 2 X 3 design yielding 6 independent cells (Factor A with level 1
>> and 2 and Factor B with level 1, 2, and 3).
>> We think that the best design to use would be to combine these
>> factors so that we have 6 groups. (11 12 13 21 22 23). We also want
>> to covary for 3 other potential confounding variables (age, sex,
>> ICV). It seems that we could do this by using a multiregression
>> analysis and a combination of dummy variables to code for the six
>> groups. However, it seems to us that we would lose the ability to
>> look at paired contrasts betwen subgroups (e.g. 11 vs 12) and to
>> extract the adjusted data for profiling the results. Similar issues
>> have come up with complex fMRI models.
>>
>> Any suggestions on how to compute a complex factorial design with
>> multiple covariates would be most appreciated.
>>
>> Thank you in advance.
>> John West
>> Brain Imaging Lab, DHMC
>>
>>
>
> --
> Dr. med. Alexander Diehl
> Oberarzt
> Klinik für Abhängiges Verhalten und Suchtmedizin
> Zentralinstitut für Seelische Gesundheit
> Universität Heidelberg
>
> J5, D 68159 Mannheim
>
> Tel.: +49 / 621 1703-3542
> Fax: +49 / 621 1703-3905
> email: [log in to unmask]
> home: www.zi-mannheim.de
>
>
Glenn T. Stebbins, Ph.D.
Associate Professor
Neurological Sciences
Rush University Medical Center
Ph: (312) 563-3854
Fx: (312) 563-4009
email: [log in to unmask]
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