[Eeglablist] Running a Second ICA

[david Schwartzman]

Hi Everyone,
 
I'm working on an analysis technique which requires that I run 2 ICAs  
on the same data set. The first is to remove standard eye artifact  
components, the second to remove components related to other  
artifacts. I don't use exactly the same data but for the second ICA I  
use about one third of each trial of the data I use for the first ICA.
 
After listening to the discussions posted here I was wondering whether  
I should also run a PCA before the second ICA or whether I would not  
need to do that because I am not using exactly the same data for the  
second ICA. If I do need to run a PCA, should I reduce the data to  
the same number of principal components for each subject or could the  
number of principal components be equal to the number of ICs retained  
after the first ICA and therefore different for each subject?
 
Many Thanks ...


David Schwartzman
Oxford Brookes University



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