Dear Tom,
> On taking an uncorrected p-value threshold of 0.001 and
> extent threshold of 100 the 'volume' program output the following;
>
> Smoothness FWHM = 12.1 11.5 Inf {mm} = 15.5 14.7 Inf {voxels}
> Search volume: S = 19461 mm^3 = 40836 voxels = 0.0 resels
> Voxel Size = [0.78125 0.78125 0.78125] (1 resel = Inf voxels)
>
> All voxel-level p uncorrected values were zero but T and Z values were
> defined.
Could you check, whether the uncorrected p-values are zero? You can do
this by right-clicking on the value. The true value will be output in
the matlab window. Note that there cannot be a smoothness estimate into
z-direction, because you have only 1 slice.
> Voxel-level corrected p-values had non-zero values, but presumably they
> are not correct?
They should be correct. As far as I can see everything is absolutely
fine for peak height p-values.
> Cluster-level p uncorrected were all 1.0
> p corrected were all 0.648
> k were all NaN
This is not what one would expect. I checked spm_P and spm_getSPM, which
are the routines used for computing the corrected p-value for cluster
size and it seems to me that the 2D-case is probably not properly taken
care of, but I'm not sure yet.
Stefan
--
Stefan Kiebel
Functional Imaging Laboratory
Wellcome Dept. of Cognitive Neurology
12 Queen Square
WC1N 3BG London, UK
Tel.: +44-(0)20-7833-7478
FAX : -7813-1420
email: [log in to unmask]
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