[FieldTrip] Fast Fourier Transform Using EEGLab

[Jörn M. Horschig]

Dear Peyton,

 

You might want to check this out:

http://www.fieldtriptoolbox.org/walkthrough#input_output_structure_of_ft_freqstatistics

And the tutorials on statistic, e.g. 

http://www.fieldtriptoolbox.org/tutorial/cluster_permutation_freq

 

However, note that doing an FFT has nothing to do with ft_freqstatistics. You need ft_freqanalysis for that and did that just fine with the code you shared (and, as with everything in life, there is not *the* correct way to do anything, but the way you did it should be fine).

 

Best,

Jörn

 

--
Jörn M. Horschig, PhD, Software Engineer
 <http://www.artinis.com/> Artinis Medical Systems  |  +31 481 350 980 

 

From: fieldtrip-bounces at science.ru.nl [mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Peyton Finley
Sent: Thursday, October 29, 2015 16:20
To: fieldtrip at science.ru.nl
Subject: [FieldTrip] Fast Fourier Transform Using EEGLab

 

Hello,

 

My name is Peyton Finley and I am an undergraduate research student at Wheaton College in Wheaton, Illinois. I am emailing you regarding how to conduct a Fast Fourier Transform using FieldTrip.

 

Specifically, I am trying to use the function ft_freqstatistics.m to gather statistics for the FFT. The function requires what is noted as a "design matrix". This is the description:

 

Nxnumobservations: design matrix (for examples/advice, please see the Fieldtrip wiki,

                                  especially cluster-permutation tutorial and the 'walkthrough' design-matrix section)

 

I checked the FieldTrip wiki site, but I was unable to find anything on this design matrix. What is the design matrix and how do I construct it?

 

Also, is this the correct way of performing a FFT on EEG data? Is there an alternate method? Before arriving at this point, I have performed the following steps.

 

cfg = [];

ft_defaults;

cfg.dataset = dataset;

preprocdata=ft_preprocessing(cfg);

data=struct2single(preprocdata);

 

%% Define cfg for ft_frequanalysis.m and run.

cfg = [];

cfg.output='fourier';

cfg.method='mtmfft';

cfg.outputfile=outputFileName;

cfg.foilim=[0 55]; 

cfg.tapsmofrq='2';

[freq]=ft_freqanalysis(cfg,data);

 

%% Define cfg for ft_freqstatistics.m and run.

cfg = [];

cfg.method='analytic';

[stat]=ft_freqstatistics(cfg, freq); 

 

 

Sincerely,

Peyton Finley

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