[FieldTrip] Averaging on a random sample

[Caspar, Emilie]

Thanks Eelke

If this can help someone else, here is the correct code:

arrondi=roundn(size(cleandata.trial,2)/2, 0);
        a = randperm(size(cleandata.trial,2));
        r1=a(1:arrondi);
        r2=a(arrondi+1:end);



        cfg = [];
        cfg.trials = r1;
        avgFCIndexHALF1 = ft_timelockanalysis(cfg, cleandata);



        cfg = [];
        cfg.trials = r2;
        avgFCIndexHALF2 = ft_timelockanalysis(cfg, cleandata);




Best,

Emilie
---------------------------------------------
Emilie Caspar

Aspirante FNRS - Ph.D. Student

Consciousness, Cognition & Computation Group (CO3)
Centre de Recherche Cognition et Neurosciences (CRCN)
ULB Neurosciences Institute (UNI)

Université Libre de Bruxelles
Av. F.-D. Roosevelt, 50
1050 Bruxelles
BELGIUM

Voice : +32 2 650 32 95
mail : ecaspar at ulb.ac.be<mailto:ecaspar at ulb.ac.be>
office: DB10-138




Le 21 nov. 2014 à 10:29, Eelke Spaak <eelke.spaak at donders.ru.nl<mailto:eelke.spaak at donders.ru.nl>> a écrit :

Dear Emilie,

You are not providing a FT data structure to ft_timelockanalysis
(which you should), instead you are providing the raw cell array of
trials (which you shouldn't). Hence, FT complains that the data is not
in a structure that it can work with.

There is a cfg-option cfg.trials, which you might like to use instead.

Best,
Eelke

On 21 November 2014 10:09, Caspar, Emilie <e.caspar at ucl.ac.uk<mailto:e.caspar at ucl.ac.uk>> wrote:
Dear Fieldtrippers,

I have a sample of 350 trials for one condition, but for statistical
analysis reasons I would like to split randomly this sample in two and
average these two parts.

so, I used the "randsample" matlab function which seems to work very well
and then I averaged this selected sample:

       randomhalf = randsample(cleandata.trial, 175);
       avgFCMiddleRing = ft_timelockanalysis(cfg, randomhalf);


However, I have the following error message :

Error using ft_checkdata (line 366)
This function requires raw or comp data as input.

Error in ft_timelockanalysis (line 105)
data = ft_checkdata(data, 'datatype', {'raw', 'comp'}, 'feedback', 'yes',
'hassampleinfo', 'yes');

Does anyone have a solution to fix the problem?

Thank you very much!

Emilie


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