[FieldTrip] Different way of calculating the covariance for LCM

[Jean-Michel Badier]

Dear Yuval,

I have to admit that I did not look at the matlab routines.
In item 2 I suppose that the covariance is calculated for each trial 
then averaged. In item 3 I would like to calculate the covariance from 
all the signal (the trials being concatenated).

Jean-Michel

Le 22/03/11 05:47, Yuval Harpaz a écrit :
> Dear Jean Michel
> As far as I know you can do it on an averaged data structure (item 1) 
> or do the same with the data structure before averaging (3). I did not 
> understand what you meant by 2.
>
> Yuval
>
> On 21 March 2011 22:58, Jean-Michel Badier 
> <jean-michel.badier at univmed.fr <mailto:jean-michel.badier at univmed.fr>> 
> wrote:
>
>     Dear fieldtrip users,
>
>     There are different ways of estimating the covariance for LCMV
>     calculation.
>     If I am correct:
>
>     1. As suggested in one of the tutorial one can apply the
>     calculation of the covariance directly on the average data (for
>     the different periods of interest that are at least a base line
>     and the period of interest).
>
>     2. Estimate the covariance from the average of the covariance
>     rather than the covariance of the average using cfg.keeptrials = "yes"
>
>     3. Estimate the covariance from the whole trials concatenated
>     together.
>     Is there an easy way to do that in fieldtrip (beside create a new
>     data set of one trial constituted of all the trials)?
>
>     Thanks
>
>     Jean-Michel
>
>     -- 
>
>     Jean-Michel Badier PhD
>
>
>     Laboratoire de MagnétoEncéphaloGraphie
>
>     INSERM U751. Aix Marseille Université
>
>     33 (0)4 91 38 55 62
>
>     _jean-michel.badier at univmed.fr_ <mailto:jean-michel.badier at univmed.fr>
>
>
>     Service de Neurophysiologie Clinique. CHU Timone
>
>     264 Rue Saint-Pierre, 13005 Marseille-France
>
>
>
>
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>
> -- 
> Y.Harpaz
>
> a link to the BIU MEG lab:
> http://faculty.biu.ac.il/~goldsa/index.html 
> <http://faculty.biu.ac.il/%7Egoldsa/index.html>
>
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