Questions concerning permutation tests on coherence data

[Jamie Johnston]

Hi All -
 
I have a couple questions.  My data set consists of 10 subjects, each
performed 5 trials under 3 different conditions.  I am trying to follow
Maris et al. 2007, computing the difference between the coherence
measures (i.e. using indepsamplesZcoh)for each pair of conditions (i.e.,
3 different comparisons) and running the permutation test (montecarlo)
on this data.  My questions are:
 
1)      All the examples I have come across only compare two
conditions...if, as in my data, we have 3 conditions and would like to
test for differences between the three, can I simply run 3 tests
comparing all the combinations?  Is this statistically sound (sorry I am
unfamiliar with nonparametric stats).
2)      For 8 of my subjects I have 5 separate channels of data,
unfortunately for two of my subjects, I have only 4 channels (and they
are missing different channels).  I would like to include them in the
coherence averages (and statistical tests), but I'm not sure how to do
this.
 
Any help would be greatly appreciated.
 
Jamie
 
_______________
Jamie Johnston, Ph.D.
Assistant Professor
Faculty of Kinesiology
University of Calgary
2500 University Dr. NW
Calgary, AB
T2N 1N4
Phone: +1 (403) 220-3649
Fax: +1 (403) 284-3553
email: johnston at kin.ucalgary.ca
website: http://www.kin.ucalgary.ca/wcm/knes/johnston.html
 

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