Teemu,
> How could the design matrix be less rank deficient when I change the event
> duration from 0.1 to 0.5? Is the duration of 0.1s somehow too short for
> Feat to put up the model? Or could it be, for some reason, that the events
> in my experiment are too tightly packed?
the duration of 0.1s is not too short for Feat. It is likely that both
design matrices with duration 0.1 or 0.5 are close to the conservative
threshold for the rank deficiency test in FEAT, with the 0.1 duration just
being the wrong side. The threshold for the rank deficiency test is
conservative and is there as warning for you to check your design. So
in your case either duration time is probably fine. Have a
look at the FAQ:
http://www.fmrib.ox.ac.uk/fslfaq/#feat_rank
Cheers, Mark.
Mark Woolrich.
Oxford University Centre for Functional MRI of the Brain (FMRIB),
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
Tel: (+44)1865-222782 Homepage: http://www.fmrib.ox.ac.uk/~woolrich
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