[FieldTrip] Fourier coefficients across tapers

Schoffelen, J.M. (Jan Mathijs) jan.schoffelen at donders.ru.nl
Thu Sep 19 09:11:02 CEST 2019

Hi Jose,

> I'm trying to compare distinct phase-based methods to compute connectivity for an EEG dataset,


> I'm using Fieldtrip to get the analytic signal of my time series, and from there I compute coherence, inter-site phase clustering, and other phase lag-based measures in Matlab. I'm running these analyses for frequencies in the gamma range so I used multitaper in Fieldtrip to compute the Fourier coefficients. It seems is not possible to average the Fourier coefficients across tapers. It would be wrong to average across the tappers the Fourier coefficients?

Yes, averaging Fourier coefficients across tapers would be wrong.

> Otherwise, it would be ok to average across the tapers the values that result from computing, for instance, coherence ? It that sensitive? 

Indeed, once cross-spectra and autospectra are computed, averaging across tapers is not a problem.

> Just to check, are the Fourier coefficients in the "rpttap" columns stacked by taper?
> I mean, do the first 15 columns correspond to the Fourier coefficients that result from applying the 15 tapers to the first trial?


Best wishes,

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