johnston at KIN.UCALGARY.CA
Sun May 3 20:00:19 CEST 2009
Hi all -
I am trying to run a monte carlo - indepsamplesZcoh - cluster on my data
using freqstatistics. I input two data files into freqstatistics with
the cohspctrm having dimensions 2 (subjects) x 10 (channels, # of
coherence spectra) x 52 (frequencies). I run into a dimension mismatch
in the function clusterstat. If I run any other statistic (i.e.,
indepsamplesT) it runs fine. When running the indepsamplesT,
clusterstat receives two inputs: statobs (520x1) and statrnd (520x100).
These dimensions make sense to me. However, when running
indepsamplesZcoh these two variables have dimensions 2340x1 and
2340x100, respectively. This happens around lines 104-108 in
indepsamplesZcoh.m with computation of the variables "chancmbsel" and
"nnewsamples." I'm not understanding what these variables do, but my
guess is that I need to setup my data files differently in the
beginning. My understanding of what this analysis protocol does is
compute the z-statistic on each channel of coherence data (10 for each
data file) and then find the difference between the z-statistic for each
channel across the data files. Once this is complete it runs the
permutations to determine the significance.
Please verify that what I have done is correct and any help with the
error I am getting would be greatly appreciated.
Jamie Johnston, Ph.D.
Faculty of Kinesiology
University of Calgary
2500 University Dr. NW
Phone: +1 (403) 220-3649
Fax: +1 (403) 284-3553
email: johnston at kin.ucalgary.ca
The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.
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