Hi
On 27 Mar 2012, at 15:18, Gartenhaus 1 wrote:
> Dear listmates,
>
> we have two questions:
>
> 1) We used the command fslstats -t <dr_2stage_Z-file> -v to extract the number of voxels and get the results
> 902629 7221032.000000 -> (902629 voxels?). However, if we extract the values (z-scores?) per voxel (fslmeants -i <dr_2_stage_Z> --showall -o output.txt), we get a number, that is exactly the double (2*902629) of the given voxel number shown above (i.e. 1.805.258 values). Can somebody explain this?
>
That's because fsl_glm currently creates both the Z and the inverted Z images (to make it easier to see what's significant in fslview). Therefore you have twice as many values as you have voxels.... This behaviour might change in the future, though
> 2) Does anybody know the difference between the files dr_stage2.nii.gz and dr_stage2_Z-nii.gz and can explain it to us and the forum?
>
The first one is a set of regression coefficients, the second one is the first one divided by the standard deviation of the residual noise (so it's t-stats actually)
hth
Christian
> Thanks in advance!
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