hello all,
i am trying to understand why the GLM analysis is unsuccessful (does
not find any activation) for one subject but not for another. i am
walking thru the report.log files for both subjects and examining
the output volumes. i have put relevant files in this location:
http://godzilla.kennedykrieger.org/~bettyann/fsl/
where the directory 1345_2.feat contains the successful GLM analysis
and directory kki_0006.feat contains unsuccessful GLM analysis.
the analysis between the two subjects seems similar up until this
step (from report.log):
/usr/local/fsl/bin/avwmaths stats/zstat1 -mas mask thresh_zstat1
the input volumes for avwmaths, stats/zstat1, have the following
ranges:
1345_2 (successful) = (-5.0684, 8.8195)
kki_0006 (unsuccessful) = (-5.8488, 5.6056)
the mask volumes look as expected with ranges of [0,1]. the output
volumes, thresh_zstat1, differ and seem to be indicative of something
going wrong. the ranges are:
1345_2 (successful) = (0, 8.8195)
kki_0006 (unsuccessful) = (0, 0)
i am confused as to what avwmaths <input> -mas <mask> <output> does.
it seems to remove all negative values in addition to simply masking
based on the output of the successful analysis. but it seems to do
more than that, given the output of the unsuccessful analysis.
any ideas as to what is going on?
thank you,
- ba
_____________________________________
BettyAnn Chodkowski F.M. Kirby Center
e: [log in to unmask] Kennedy Krieger Institute
v: 443.923.9524 707 N. Broadway
f: 443.923.9279 Baltimore, MD, USA 21205
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