Hello,
>We have an event related design containing 5 sessions, each session composed of 30 trials, each trial lasting 11
>seconds, TR 2.5, resulting in 132 WHV per session. For each trial we obtain a rating (1-3) from the subject.
>Therefore, in addition to comparing different trial types in a classical way, what we would also like to do is
>perform a regression of the subjective responses with activation patterns. In essence, it would be much like
>adding in the 132 realignment movement parameters. Our question, however, is that we only have 30 subjective
>responses, one for each trial (rather than one value per WHV as with realignment parameters), and hence are
>not sure how to set-up this kind of a regression.
It has been suggested to simply pad the regressor file with 0's. But is it okay to use 0? Specifically, I would
like to check whether or not SPM models a regressor value of 0 as nothing (null-value). That is, are onset
scans in the regression that are assigned a value of 0 not included in the regression? I suspect not, but want
to check with the community and know for sure.
I haven't found a satisfying answer in SPM documentation, but any pointers would be immensely helpful as well.
Many thanks!
-Peter Hu
phu AT bidmc DOT harvard DOT edu
(trying to cut down my daily intake of spam)
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