Dear SPM'ers,
I have a query regarding model specification in our SPM analysis of SPECT
neuroreceptor images. We have 4 groups, i.e., Normal controls and three
dementia
groups.
We are initially interested in group differences between each dementia group
and normal ageing. My question is, in assesing these main effects should I
include
all 4 groups in the model with each group corresponding to a single
condition?
Or, carry out 3 separate models with the control group as one condition and
one of the dementia groups as another condition?
Any advice on this would be gratefully received.
Thanks in advance
Sean Colloby
Research Associate
Imaging Research Group
Institute for Ageing and Health
Wolfson Research Centre
Newcastle General Hospital
Newcastle-upon-Tyne
NE4 6BE
UK
Tel: +44 (0) 191 256 3372
Fax: +44 (0) 191 219 5051
email: [log in to unmask]
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