[Eeglablist] Downsizing Number of Electrodes

[Stephen Politzer-Ahles]

Hi Marco,

Other than the size of the datasets, I can't think of any drawbacks to
working with all 32 electrodes from the beginning. I'm not sure what
exactly your data processing entails, but at least in my experience most of
the data processing steps (e.g. filtering, baseline correction, epoching)
work exactly the same whether you have many or few electrodes. For
processes (such as filtering and baseline correction), electrodes should be
independent from one another, but for some things (such as ICA
decomposition, and possibly referencing--if you want to use average
reference) the number of electrodes does matter, and in every case I can
think of it's best to have as much of your data as possible. So my thought
would be, as long as you have sufficient space, it's probably best to keep
all electrodes through the entire data processing.

Best,
Steve

On Sat, Jun 23, 2012 at 10:46 PM, Marco Montalto <montaltomarco at onvol.net>wrote:

> Dear List,
>
> I have what most probably is a really banal question but which I thought I
> should gather advise from the experts regarding the issue before committing
> myself to a decision. I am collecting data from 32 electrodes. Now at the
> final stages I might want to use data from only 10 of those electrodes for
> statistical analysis. From your experience do you think running the entire
> data processing procedure on the 32 electrodes and then running statistical
> analysis on only 10 of those electrodes would be a problem? I envisage that
> working on 10 electrodes only from the very start would require much less
> work but I don't mind the added task. My concern is whether the data would
> look different in the two scenarios i.e. working on 32 electrodes, would,
> let's say, data from electrode Cz look different from data from electrode
> Cz obtained from working with, initially, 10 electrodes only?
>
> Looking forward to your replies.
>
> Thanks and regards,
> Marco
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-- 
Stephen Politzer-Ahles
University of Kansas
Linguistics Department
http://www.linguistics.ku.edu/
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