Dear Satra, Bas and list,
>
> But, in SPM X is not really the created design matrix. It is a reduced
> form and contrasts get mapped to this reduced form. Hence, I'm trying
> to understand why the designers of SPM didn't allow empty conditions.
>
I didn't know that SPM2 does that for you and I couldn't find it in the
code. AFAIK, spm_get_ons creates a stimulus matrix u fomr the specified
onsets and spm_Volterra convolves this stimulus matrix (a collection of
delta (stick) functions) with the selected basis set to yield the design
matrix X. After that only filtering and whitening is applied to it.
What am I missing here? Could you point me to this design matrix
reduction in the source code?
Thanks, Jan
--
Jan Gläscher
NeuroImage Nord
Department of Neurology, Bldg S10
University Hospital Hamburg-Eppendorf
Martinistr. 52
D-20246 Hamburg
Germany
Phone: +49-40-42803-7890
Fax: +49-40-42803-9955
Email: [log in to unmask]
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