Dear SPM-users
I have a question wrt running an FIR RFX analyis in marsbar.
For my analysis, I have modeled my events using an FIR with 16 bins and
length=TR (2s).
I have performed a second level analysis in SPM5 and would like to also
perform an ROI analysis on one of the regions.
I have 14 subjects * 16 bf = 224 timepoints and 1 region. I run a
first-level ROI analysis and extract summary values for each of these
points. I then write them out to a matrix, lets call it Y, (size: 224x1)
to use as the
data for a second level analysis.
I load the SPM second level design matrix (the one that I have already
estimated using SPM5) and import matrix Y as the data (option summary
time course for region). I then
estimate the model, provide a basic F-contrast (eye(number of basis
functions)) and look at the statistics table below:
Contrast name ROI name: Extra SS: F statistic:
Uncorrected P: Corrected P
---------------------------------------------------------------------------------------------------------------------------
Fcon-all Matlab input_1: 242872823.12: 697149249.02:
0.000000: 0.000000
For obvious reasons, I think that these results are suspicious.
But I am not sure what is wrong. Am I doing something wrong or is this a
problem with non-sphericity correction?
The other thing that looks really suspicious, is the design matrix, when
setting up the contrasts It looks like random image, the diagonal structure
is non-existent and the effects of interest contrast matrix is also very
random - to me at least (please see attached image "screenshot.jpg").
Have you ever come across such a problem before?
Your help will be highly appreciated.
Thank you,
Marina
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