I think I would just optimize with one condition and then do the post-hoc sorting into 5. It should be ok if the subject is responding randomly. I don't have a tool for power, but optseq will give the variance reduction factor, which goes in the denominator of the t-test. This assumes you are testing an omnibus contrast, though. I think FSL might have something to test power.
doug
Kathrine Shepherd wrote:
Hello--
I'm designing an event-related task that does not have predefined conditions. instead, I plan to do some post-hoc sorting based on performance and stimuli characteristics. I expect that after sorting, I will have 5 conditions- but it could be more or less. Is it advisable to determine the stim presentation schedules in optseq as if I had already specified predefined conditions? Or is it optimal to just completely randomize the jitter without making any assumptions about the response function?
Also is there a tool available to estimate the stat power of my schedules after I've defined them?
Many thanks for your advice, -Kathrine _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer