[FieldTrip] Permutation statistics

Hwee Ling Lee hweeling.lee at gmail.com
Sun Mar 23 15:19:30 CET 2014

Dear Vitoria,

Thanks for the tip.

I'm trying to perform a within-trial analysis.

I've got two sets of data, before and after resting state EEG activity.
First set has 54 trials and second set has 51 trials. Hence, my cfg.design
= [ones(1, 105); ones(1,54), ones(1,51)*2].

I've set up the statistical analysis like this:

    cfg = [];
    cfg.layout = lay;
    cfg.channel = 'all';
    cfg.latency = 'all';
    cfg.trials = 'all';
    cfg.frequency = 'all';
    cfg.avgovertime = 'no';
    cfg.avgoverfreq = 'no';
    cfg.avgoverchan = 'no';
    cfg.parameter = 'powspctrm';
    cfg.method = 'montecarlo';
    cfg.statistic = 'depsamplesT';
    cfg.numrandomization = 1000;
    cfg.design = design;
    cfg.uvar = 1;
    cfg.ivar = 2;

    [stat] = ft_freqstatistics(cfg, post_c200freq, pre_c200freq);

However, I got an error message:

Error using ft_statfun_depsamplesT (line 84)
Invalid specification of the design array.

Error in ft_statistics_montecarlo (line 285)
  [statobs, cfg] = statfun(cfg, dat, design);

Error in ft_freqstatistics (line 323)
  [stat, cfg] = statmethod(cfg, dat, cfg.design);

Can someone please tell me what parameters did I specify wrongly? Thanks.

Best wishes,

On 21 March 2014 20:10, Vitória Piai <v.piai.research at gmail.com> wrote:

>  Dear Hweeling,
> There is nothing inherent to the ft_freqstatistics function that makes it
> special for MEG, rather than for EEG data. If you've been using other
> FieldTrip functions, you probably have used cfg.channel before. These are
> the channels present in your EEG data.
> How you should set some of the other parameters depends only on your
> design, not on whether the data are from MEG or EEG.
> Maybe you can specify what is unclear to you when calling the function so
> that you can get appropriate help!
> Good luck, Vitoria
> On 3/21/2014 3:36 PM, Hwee Ling Lee wrote:
> Dear all,
>  I've got EEG datasets for 64 channels, and I would like to perform
> permutation statistics on the power frequency analyses to compare the two
> conditions (before and after resting state periods).
>  However, I'm not sure how to operationalise the statistical analyses
> since most of the examples on the website are for MEG datasets.
>  I would appreciate very much if someone could help me on this! Thanks!
>  Cheers,
> Hweeling
> _______________________________________________
> fieldtrip mailing listfieldtrip at donders.ru.nlhttp://mailman.science.ru.nl/mailman/listinfo/fieldtrip

Dr. rer. nat. Lee, Hwee Ling
German Center for Neurodegenerative Diseases (DZNE) Bonn

Email 1: hwee-ling.lee<at>dzne.de
Email 2: hweeling.lee<at>gmail.com


Correspondence Address:
Ernst-Robert-Curtius Strasse 12, 53117, Bonn, Germany
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