> From [log in to unmask] Fri Sep 17 09:02:55 1999
> Date: Fri, 17 Sep 1999 09:00:57 +0100 (BST)
> Reply-To: Klaus Ebmeier <[log in to unmask]>
> Content-MD5: UH7Fx851XuJxWrEONhBCwg==
> Subject: Re: Covariates & Correlations
Dear Klaus,
> In order to examine the effect of the covariate on brain
> perfusion/metabolism within subjects in SPM (which I believe is what
> correlating difference scans with difference psychometric measures
> does) you would have to model subject (to remove intersubject
> variance), not condition, but covariate, which would in the absence of
> a condition effect acount for the variance within subjects.
>
> If this is true, how do you configure the model within SPM to model
> only subject and covariate effects (remember there are two scans and
> two covariate measures per subject) without modelling condition?
Simply use multi-subject, covariates only.
With very best wishes - Karl
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