When specifying my design, SPM2 gets stuck after I select the hrf model, but
only when I change the defaults for fMRI statistics to match my data....
Before specifying a design for an fMRI experiment, one usually selects "default"
to change the values according to one's data. The default in Statistics-FMRI
before I adjust it for my data is:
threshold: .001
no. bins/TR: 16
bin sampled: 1
Without adjusting the default, I specify my design:
interscan interval: 2
scans per session: 230 230 230 230
specify design in secs
choose hrf
Volterra: no
And so on. When I leave the default as it is, I have no problem specifying my
design. However, these default values don't match what I actually have. The
problem occurs only when I specify the number of bins that I actually have in
my design, which is 26 bins. I've checked that it works regardless of what
p-value I choose, which bin was sampled, and if I choose numbers other than 26.
For some reason, SPM2 runs into a matrix error once I've selected hrf only if I
have entered 26 as the number of bins.
Here is what I want the values in fMRI Statistics to be:
threshold: .01
no. bins/TR: 26
bin sampled: 13
The problem cannot be that I'm giving the wrong values for my specific data
because it doesn't know where to find my data at this point in the process. It
will work even when I make up bogus numbers... just not when I enter 26 bins.
Any ideas on what the problem is? Is this a bug in the program?
Thanks,
Michelle
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