[FieldTrip] Does deleting bad channels in single subjects create problems for grand average later?

[Hwee Ling Lee]

Dear Kathrin,

Re your previous post about repairing bad channels, I've also tried this on
Fieldtrip and it works for me. I've not used the triangulation method, but
maybe you could try again. I guess it depends on your template. For me, I
was using Easycap 64 channels, but maybe it's different for you. Here's how
I set up my repair channels options:

    % repairing bad channels with averaged of its neighbours

load('/home/leeh/Programs/fieldtrip-20140803/template/layout/easycapM11.mat');

    cfg_neighb.method = 'template';
    cfg_neighb.layout = lay;
    neighbours = ft_prepare_neighbours(cfg_neighb, data2);

    cfg = [];
    if strcmp('S004', dir_analysis{sub}) == 1
        cfg.badchannel = {'C4', 'TP9', 'FC4', 'C2', 'F4'};
    end
    cfg.trials = 'all';
    cfg.method = 'average';
    cfg.layout = lay;
    cfg.neighbours = neighbours;
    data3 = ft_channelrepair(cfg, data2);

Re removing bad channels. Your question regarding if this will create
problems for your grand average over subjects later. Well, it depends which
channels you remove for individual subjects. As far as I'm aware, when you
averaged your data across subjects, it will only pick the common channels
across subjects for the statistical analyses. When you plot, you can always
call for the template layout (e.g. 'EEG1020.lay'). This will plot the
available channels across all subjects, and leave out the ones that are not
in the data.

I hope this helps.

Cheers,
Hweeling



On 17 August 2014 11:23, KatrinH Heimann <katrinheimann at gmail.com> wrote:

> Dear all
> I still have problem with the channel interpolation (just not working at
> all, without error message, see my previous post). Now I am thinking if I
> just remove the bad channels for the single subjects and leave it like
> that. My question is though: Will this create problems for my Grand average
> over subjects later (as in each subject I remove different channels)? and
> which layout do I have to use to plot my Grand average data later?
> Every help is very welcome
> Cheers
> k
>
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-- 
=================================================
Dr. rer. nat. Lee, Hwee Ling
Postdoc
German Center for Neurodegenerative Diseases (DZNE) Bonn

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

https://sites.google.com/site/hweelinglee/home

Correspondence Address:
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