[FieldTrip] Simulate data to compare methods

[Max Cantor]

Hi Nico,

I'm not sure about the second question, but as for the first question, you
can manually set the scales for ft_singleplotTFR using cfg.zlim.

Hope that helps,

Max

On Tue, Jan 27, 2015 at 11:50 AM, Nico Weeger <nico.weeger at googlemail.com>
wrote:

> Hello FieldTrip community,
>
>
>
> I am new to FieldTrip and I try to simulate data to compare the
> ft_frequanalysis methods Hanning, Multitaper and Wavelet.
>
> Therefore I simulate Data manually using different latency, amplitude and
> frequency combinations using the following equation:
>
> sig1 = exp(-(t-lat1).^2/(2*sigma1))*amp1.*sin(2*pi*f1*t);
>
> sig2 = exp(-(t-lat2).^2/(2*sigma2))*amp2.*sin(2*pi*f2*t);
>
> sig3 = exp(-(t-lat1).^2/(2*sigma1))*amp1.*sin(2*pi*f2*t);
>
> sig4 = exp(-(t-lat2).^2/(2*sigma2))*amp2.*sin(2*pi*f1*t);
>
> sig = sig1+sig2+sig3+sig4;
>
> where amp1=20; amp2 = 5; lat1= 1.7; lat2 = 2.3; f1 = 12; f2 = 60;
>
>
> After using ft_frequanalysis (see the following cfgs)
>
>
> *Cfg Wavelet:*
>
> cfg = [];
>
> cfg.output     = 'pow';
>
> cfg.channel    = labels;
>
> cfg.method     = 'wavelet';
>
> cfg.width      = 7;
>
> cfg.gwidth     = 3;
>
> cfg.foilim     = [1 70];
>
> cfg.toi        = 0:0.05:2;
>
> TFRwave = ft_freqanalysis(cfg, data_preproc);
>
>
>
> *Cfg Hanning / Multitaper:*
>
> cfg = [];
>
> cfg.output     = 'pow';
>
> cfg.channel    = labels;
>
> cfg.method     = 'mtmconvol'
>
> cfg.foi        = 1:1:70
>
> cfg.tapsmofrq  = 0.2*cfg.foi;
>
> cfg.taper      = 'dpss' / ‘hanning’;
>
> cfg.t_ftimwin  = 4./cfg.foi;
>
> cfg.toi        = 0:0.05:2;
>
> TFRmult1 = ft_freqanalysis(cfg, data_preproc);
>
>
>
>
> the data is plotted with ft_singleplotTFR (see cfg below)
>
>
> *cfg singleplot:*
>
> cfg = [];
>
> cfg.maskstyle    = 'saturation';
>
> cfg.colorbar     = 'yes';
>
> cfg.layout       = 'AC_Osc.lay';
>
> ft_singleplotTFR(cfg, TFRwave);
>
>
> Two problems occur. First, the power scale of wavelet and
> Multitaper/Hanning differs extremely (Multi 0-~100 and Wavelet 0-~15*10^4).
>
> 1.       How can I get the scale of all methods equal, or do I have to
> change the Wavelet settings to get the right scale of the values?
>
> Second, the best result of Multitaper analysis is performed using only one
> Taper. The goal was to get a result, where the advantages and disadvantages
> of Multitaper analysis compared to the other methods can be seen.
>
> 2.       How can I change the simulation so that more tapers show better
> results than a single taper does?
>
>
> Thank you for your time and help.
>
>
> Regards,
>
>
>
> Nicolas Weeger
>
> Student of Master-Program Appied Research,
>
> University Ansbach,
>
> Germany
>
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>



-- 
Max Cantor
Lab Manager
Computational Neurolinguistics Lab
University of Michigan
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