Thanks a lot - I've been using a single 4D covariate (treating voxel absent/present as a categorical). I'll check how many 4D covs I'd need and see if the servers are up to it....
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Hi - you probably want to be using 4D covariates - however this will make the analysis even larger.
If you computer struggles with this it might be better to fill in the missing values (if they are not too largeā¦..) using dilation options in fslmaths?
Cheers.
On 2 Mar 2012, at 09:24, Jonathan O'Muircheartaigh wrote:
Hi,
I'm running a group analysis in randomise with a pretty large dataset. Some of the subjects have missing voxels and I was wondering if this can be modelled using voxelwise covariates? I've created a *single* covariate with voxel present / voxel absent values - is this correct or should I have a single voxelwise covariate for each individual with missing voxels (...RAM permitting...).
All the best,
Jonathan
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Stephen M. Smith, Professor of Biomedical Engineering
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