Hi Simon,
Thanks lots for your helpful reply! I get the picture now.
Regards,
Glad
On 14.05.2012 15:16, Eickhoff, Simon wrote:
> Dear Glad
>
>
> Masking is just that: It just doesn't show those voxels that are not in your mask images (exclusive mask) / just shows voxels within your mask image (inclusive mask) [look at spm_getSPM at about line 600]. The statistics, more precisely the correction for multiple comparisons), however, still runs with respect to the initial analysis space.
>
> Smal volume correction, in contrast, only corrects for the smaller search volume and provides correcte p-values for this new analysis space. It doesn't however, update the image you see in the glass-brain.
>
> So it is actually a good idea to combine both, mask out voxels outside the mask (for dispay) and then re-compute your corrected statistics using SVC for the same mask.
>
>
> Best
> Simon
>
>
>
> ________________________________________
> Von: SPM (Statistical Parametric Mapping) [[log in to unmask]]" im Auftrag von"Glad Mihai [[log in to unmask]]
> Gesendet: Montag, 14. Mai 2012 10:46
> An: [log in to unmask]
> Betreff: [SPM] Difference between mask with image and small volume
>
> Hi,
>
> can someone explain to me the difference in calculation between masking
> (apply masking) a contrast with an image (let's say an anatomical ROI),
> and a small volume correction?
>
> Regards,
> Glad
>
>
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