On Sat, 5 Mar 2005 17:06:19 +0000, Joe Maisog <[log in to unmask]> wrote:
>> A few years ago it was common for people to do global scaling
>> in SPM fMRI analyses. Nowadays the advice is that, in most
>> situations, it shouldn't be done.
>
>Does anybody out there still routinely perform global scaling on their
fMRI
>data? I am curious to see what the consensus is.
>
>Thanks very much!
>
>Joe
I don't know what individual groups do, but the consensus among SPM folk
seems to be not to do it.
One notable exception is Keith Worsley.
For people I know, the debate assumes that global scaling shouldn't be
done, and the only question is whether to use grand mean scaling only, or
to do "voxelwise scaling" so that effect sizes are in percent signal
change.
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