# [FieldTrip] Fast Fourier Transform Using EEGLab

Peyton Finley peyton.finley at my.wheaton.edu
Thu Oct 29 16:19:40 CET 2015

```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:

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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