Dear Maria,
Maria Densmore wrote:
> Hello ,
>
> Thanks for your feedback.
> I still need clarification of my two concerns.
>
> 1) I don't quite understand how to set my design matrix since there is no
> baseline condition to subtract the task from. What I do have is, one task
> (eyes closed)that continues throughout the entire 110 volumes acquired.
The design matrix consisted, as far as the paper describes it, of the 3
regional mean time series (made by the 12mm spheres round the peaks of
activity). The degree of freedom was computed as n-3 so I guess there
was no intercept (ie the data should already have zero mean).
As said this is quite a dodgy way of estimating functional connectivity
(the regressors are far from orthogonal), this is usually solved by
using the partial correlation, which ignores the part of the variance
that is explained by more than one regressor.
Best wishes
Alle Meije Wink
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