hi steve
i'm not quite clear on what you mean - should i select the higher level
COPEx.feat directory and NOT select the 'convert PE/COPE to %' and take the mean
value produced then divide this by the baseline level? what exactly do you mean
by baseline level from the first level? do i get this by running Featquery on
one of my first level (single session) directories and selecting
filtered_func_data and 'convert PE/COPE to %'? and then taking the mean value
for filtered_func_data given in the output. but since i have 5 lower level
directories (from my 5 sessions) is the mean of the filtered_func_data from one
session sufficient or do i need the average from all 5?
thanks again
jane
In message <[log in to unmask]>
FSL - FMRIB's Software Library <[log in to unmask]> writes:
> Hi - yes, at the moment these % changes don't make sense at higher level,
> as the "baseline level" used to convert PE or COPE into a % doesn't mean
> anything useful in the 2nd-level input data (which is COPEs from first
> level, not image data). Therefore you would need to convert the non-% data
> yourself by going back to the first-level baseline levels. Sorry!
>
> Cheers.
>
>
> On Wed, 17 Nov 2004, Jane Aspell wrote:
>
> > Hi all
> >
> > I'm trying to get % change values out of Featquery and am having some
> > trouble - the output gives me mean values of 2000-4000! I'm running
> > Featquery on the results of a higher level analysis - a fixed effects
> > analysis which combined 5 sessions for a single subject - so am selecting
> > something.gfeat/copeX.feat directories.
> > It was suggested to me that my mask (a retinotopic map) could be including
> > voxels outside of the brain and this could be causing the huge values, but
> > when i tried eroding the mask it made almost no difference.
> > When i run Featquery on the first level directories from single sessions I
> > get mean values around 0.2, which seems reasonable.
> > any idea what the problem is? my experiment was a simple block design.
> >
> > many thanks,
> >
> > Jane Aspell
> >
>
> Stephen M. Smith DPhil
> Associate Director, FMRIB and Analysis Research Coordinator
>
> Oxford University Centre for Functional MRI of the Brain
> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
>
> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>
--
Dr Jane Aspell
Department of Experimental Psychology, University of Oxford,
South Parks Road, Oxford, OX1 3UD
tel: +44 (0)1865-281606
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