[Eeglablist] Re-referencing/rank/ICA

[Ivonne Weyers]

Dear all,

I have a question regarding rank computation before ICA. So far, I have 
been using the built in MATLAB function rank(), but it has now returned 
weird results (as has been talked about here 
<https://sccn.ucsd.edu/pipermail/eeglablist/2012/004670.html>), which is 
why I would simply like to specify rank individually for each data set 
in the pca option. I would greatly appreciate it if someone could 
confirm my following reasoning for the rank adjustment.

My data have been recorded from 28 channels with average reference, 27 
of which will enter the ICA (the monopolar EOG channel is excluded- yes, 
I could also include it). The 27 channels have been re-ferenced to 
average mastoids (TP9, TP10- is it correct to include these in the ICA 
at all?). For some subjects, a maximum of two channels have been 
interpolated.

So my question is: if 27 channels enter the ICA, rank would be 26 for 
datasets without any interpolated channels (deficient by 1 due to 
re-referencing) and 26 - (number of interpolated channels) for those 
with interpolations?

Thank you & best,

Ivonne

-- 
Ivonne Weyers, M.A.
Research Group Psycho- and Neurolinguistics
Institute of Cognitive Science
University of Osnabrück
Room 50/104
Wachsbleiche 27
49090 Osnabrück
Germany

Phone: +49 (0) 541-969-2247
e-mail: ivonne.weyers at uni-osnabrueck.de