[FieldTrip] Help with ft_sourcestatistics

[STEPHAN MORATTI]

Dear Francisco,

It seems that in your source data you probably have the average across
subjects, but the individual source data for each subject is missing. You
may store them in individual cells and then submit these cells to the
source statistics.

Best,

Stephan


El jue, 17 nov 2022 a las 11:32, FRANCISCO JAVIER GÓMEZ CAMPOS via
fieldtrip (<fieldtrip at science.ru.nl>) escribió:

> Dear community,
>
> I am having problems using the ft_sourcestatistics function. I would like
> to use this function
> to conduct a within-subject analysis to establish which areas show
> differences between two
> experimental conditions. I mainly have doubts about two aspects, the first
> one is about how to
> attach the source analysis data, and the second one is about the design of
> the design matrix.
>
> Regarding the data coming from the source analysis, I have the sources
> separated by
> conditions (obtained by following this tutorial
> https://www.fieldtriptoolbox.org/tutorial/beamformer/):
>
> Source analysis data for each condition:
>
> freq: 4.8302
> cfg: [1×1 struct]
> dim: [85 110 132]
> inside: [1234200×1 logical]
> pos: [1234200×3 double]
> method: 'average'
> avg: [1×1 struct]
>
>
> avg:
>
> pow: [1234200×1 double]
> noise: [1234200×1 double]
> filter: {1234200×1 cell}
> label: {61×1 cell}
> filterdimord: '{pos}_ori_chan'
>
>
> The code I use is the following (based on this code in this tutorial
> https://www.fieldtriptoolbox.org/example/source_statistics/ ) :
>
> design=[1 2]; %for 2 conditions
> % run sourcestatistics using cluster based correction %
> cfg = [];
> cfg.dim = sourceanalysis_condition1(1).dim;
>
> cfg.method = 'montecarlo';
> cfg.statistic = 'ft_statfun_depsamplesT';
> cfg.parameter = 'pow';
> cfg.correctm = 'cluster';
> cfg.numrandomization = 'all';
> cfg.alpha = 0.05; % note that this only implies single-sided testing
> cfg.tail = 0;
> cfg.design(1,:) = [1:length(find(design==1)) 1:length(find(design==2))];
> cfg.design(2,:) = design;
> cfg.uvar = 1; % row of design matrix that contains unit variable (in this
> case: trials)
> cfg.ivar = 2; % row of design matrix that contains independent variable
> (the conditions)
> stat = ft_sourcestatistics(cfg, sourceanalysis_condition1,
> sourceanalysis_condition2)
>
>
> When I run this code, I get the following error:
>
> Error using ft_statfun_depsamplesT (line 83)
> The data must contain at least two units of observation (trials or
> subjects).
>
>
> I understand that my design matrix and/or the structure of
> sourceanalysis_condition are
> wrong, I have tried different combinations and I cannot find the solution.
> I hope you can
> guide me in this regard so that I can adapt it to the conditions of my
> study.
>
> Thanks,
> Francisco Javier Gómez,
> Instituto de Biomedicina de Sevilla (IBIS)
> _______________________________________________
> fieldtrip mailing list
> https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> https://doi.org/10.1371/journal.pcbi.1002202
>


-- 

Stephan Moratti, PhD
Profesor de Psicología Experimental
Departamento de Psicología Experimental
Facultad de Psicología
Center for Cognitive and Computational Neuroscience
Universidad Complutense de Madrid
smoratti at ucm.es



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