Hi SPMers,
I have a very naive question about inclusion of time derivative in
analysing block design fMRI data (TR = 2s, block duration = 20s). Is it
suggested to include time derivative for block design or it is only used
for event-related?
I have tried to compare the results of (1) HRF alone and (2) HRF + time
derivative in the design. In (2), I only put "0" for the column of time
derivative. I assume I would get the same result as in (1) since "time
derivative" is not inluded in the t-test although it does have a column
in the design. But the results are not the same.
Any suggestions and explainations are appreciated.
Thanks.
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