# [Eeglablist] Getting summary conclusion of band power analysis

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Thu Feb 27 21:55:14 PST 2014

```Dear Tommaso,

Sorry for delay.
There is no dumb question. Your question is completely reasonable. The
inconvenience you experienced is because EEGLAB does not allow users to

For your request, please try the code below. If you want to calculate the
ratio. add up all power for a denominator.

% for your epoched data, channel 1
[spectra,freqs] = spectopo(EEG.data(2,:,:), 0, EEG.srate);

% delta=1-4, theta=4-8, alpha=8-13, beta=13-30, gamma=30-80
deltaIdx = find(freqs>1 & freqs<4);
thetaIdx = find(freqs>4 & freqs<8);
alphaIdx = find(freqs>8 & freqs<13);
betaIdx  = find(freqs>13 & freqs<30);
gammaIdx = find(freqs>30 & freqs<80);

% compute absolute power
deltaPower = 10^(mean(spectra(deltaIdx))/10);
thetaPower = 10^(mean(spectra(thetaIdx))/10);
alphaPower = 10^(mean(spectra(alphaIdx))/10);
betaPower  = 10^(mean(spectra(betaIdx))/10);
gammaPower = 10^(mean(spectra(gammaIdx))/10);

Makoto

2014-02-21 10:11 GMT-08:00 Tommaso Martino <tommartin at hotmail.it>:

> Dear all,
> I'm new to EEGlab, and maybe this is a dumb question. By the way, let's
> consider I have 2 seconds EEG registration for 1 electrode (the simplest
> example).
> I want to analyze it, saying, for example, that "alpha relative power is
> 25%, beta relative power is 15%, theta relative power is 19%, etc..." (for
> a total of ~100%).
> As far as I now, this is the commonest method to summarize results of a
> QEEG analysis in published studies (read those from Babiloni, for example).
>
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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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