[FieldTrip] global field power

[Nathan Weisz]

Hi,

I think Nenad means something like (untested code):
data.GFP=mean(data.avg.^2)

or for 
data.RMS=sqrt(mean(data.avg.^2))

Good luck,
n

On 08.11.2012, at 20:46, Eelke Spaak wrote:

> Dear Nenad,
> 
> The only definition I could find for 'global field power' in the
> context of EEG is indeed as JM suggested, the standard deviation over
> channels. Of course, computing this std collapses across the channel
> dimension, so you end up with a dimensionality of 1 where previously
> there was the dimensionality of nChannels.
> 
> If this is not what you are after, you need to give us a clear
> definition of what you mean by 'global field power'.
> 
> Best,
> Eelke
> 
> On 8 November 2012 20:34, Nenad Polomac <polomacnenad at gmail.com> wrote:
>> Dear Jan and Elke,
>> 
>> Thank you for your ansewers!
>> I have applied The Matlabs std function on data.avg matrix and it doesn't
>> give me good results. Namely, it returns matrix with  [1 x time points] so
>> it reduces number of channels to one, which is not what I want. I believe
>> this is because the sum function sums data column-wise. My question is could
>> I do only sqrt(data.var). Would this result be proper way of calculating
>> global field power?
>> 
>> All the best!
>> 
>> Nenad
>> 
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