Hi David,
it depends on your model. If you're just looking at
group differences, then no, it is not required. If you
want to add a covariate such as the age for instance,
then you need to demean both the age covariate and
your data with -D (please see the manual:
http://www.fmrib.ox.ac.uk/fsl/randomise/index.html. In
any case, randomise is clever enough to notice and
warn you when you should have demeaned the data...
Best,
Gwenaelle
--- David Kideckel <[log in to unmask]> a écrit
:
> Dear FSLers,
>
> When using the Randomise option for TBSS analyses,
> is it necessaryto use the
> -D option to demean the data? It is necessary for
> fMRI time series data,
> but I don't know whether it is sutable for DTI data.
>
> Thanks.
>
> David Kideckel
>
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