[FieldTrip] Power Spectra - averaging across samples

Pelt, S. van (Stan) stan.vanpelt at donders.ru.nl
Wed May 27 11:46:25 CEST 2015

Dear Fedrica,

Yes it is. You can get to the same outcome directly by just specifying cfg.keeptrials=’no’ (the default), but I assume you want to do some single-trial analysis later on.


From: fieldtrip-bounces at science.ru.nl [mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Federica Mauro
Sent: woensdag 27 mei 2015 11:28
To: FieldTrip discussion list
Subject: [FieldTrip] Power Spectra - averaging across samples

Dear all,
I have a question about spectral power computation.
I'm using this code
cfg            = [];
cfg.output     = 'pow';
cfg.method     = 'mtmfft';
cfg.taper      = 'hanning';
cfg.foi        = 5:1:40;
cfg.t_ftimwin  = 5./cfg.foi;
cfg.tapsmofrq  = 5;
cfg.keeptrials = 'yes';
cfg.channel    = {'Fp1' 'Fp2' 'F7' 'F3' 'Fz' 'F4' 'F8' 'T3' 'C3' 'Cz' 'C4' 'T4' 'T5' 'P3' 'Pz' 'P4' 'T6' 'O1' 'O2'};
freqfourier    = ft_freqanalysis(cfg, eeg);
and the power spectrum output is a matrix 138 (samples) X 19 (electrodes) X 36 (frequencies), for each subject.
My question is: is it correct to average the data across the samples dimension?
Thank you in advance!

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