Dear SPM gurus,
I was wondering about a few things related to combining multiple runs of
an experiment per subject and then analyzing it as one long experiment.
We currently do 4 runs of a Stroop task, each run being identical
(except for the order of the trial types, which is randomized in each
run). Each run is ~6 minutes long, so when we run them individually
through SPM 180 images are produced. Now, for a number of subjects there
is a great deal of movement, and thus some of their runs can't be
included. Is it acceptable to, say, combine 2 runs from one subject, 4
runs from another, etc.? And after all the subjects are done, do a 2nd
level group analysis? I would like to know if this is possible in SPM,
first off (can con images with different # of scans be combined like
this), and second if this is acceptable from a research perspective
(will our results be real, etc).
As usual, if any clarification is needed, just ask.
Thanks,
Chris
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