[FieldTrip] missing channels and time locked grand average

Arjen Stolk a.stolk8 at gmail.com
Fri Aug 4 17:20:31 CEST 2017

Hi Arnold,

There's a cfg.method = 'nan' option in ft_channelrepair, which creates NaN
data for specified channels. As a result, these channels are still
considered in the group-level statistics, provided other subjects have data
for the same channels. However, I don't know whether timelockgrandaverage
can yet deal with these NaN channels too.


On Fri, Aug 4, 2017 at 7:45 AM, Arnold Kochari <a.kochari at uva.nl> wrote:

> Dear FieldTrip community,
> I have a question about what seems to be an old problem with no solution
> posted yet.
> I have deleted bad channels in some participants during preprocessing. Now
> I would like to compute grand average ERPs using ft_timelockgrandaverage.
> However, if a channel has been deleted in at least one participant, the
> mean for it does not get calculated. What I would like to see is just that
> the average is calculated among the remaining participants.
> I understand that there might be some strong arguments for the absence of
> this functionality. I also know about the possibility to interpolate the
> deleted channels using channelrepair, but I do not really agree with it.
> Is there any way to calculate grand averages the way I would like to do
> it? The only solution that I can think of right now is exporting the data,
> making the calculation in R and then importing the averages it again, but
> that would require a lot f time.
> Kind regards,
> Arnold Kochari
> PhD candidate, Institute for Logic, Language and Computation, University
> of Amsterdam
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> fieldtrip at donders.ru.nl
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