Hi Rachel,
I can't answer your questions directly, but the following article was very useful to me.
Reimold M, Slifstein M, Heinz A, Mueller-Schauenburg W, Bares R. Effect of spatial smoothing on t-maps: arguments for going back from t-maps to masked contrast images. J Cereb Blood Flow Metab. 2005 Oct 5; [Epub ahead of print]
Carlos
>>> Rachel Grossman <[log in to unmask]> 11/11/05 6:44 PM >>>
Hi SPMers,
From SPM99 manual it looks like explicitly masking is not an usual option, motivated by the fact that the images were masked during normalization.
I have 2 questions:
1. Is it wrong to explicitly mask while performing a one t test for one condition with a mask created from another condition?
2. If it is not absolutely incorrect and if by masking there are kept only the common voxels what is the difference between such an approach and a conjunction between the two conditions?
Thanks for your answer,
Rachel Grossman, PhD
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