[FieldTrip] Different way of calculating the covariance for LCM

Luisa Frei l.frei at psy.gla.ac.uk
Tue Mar 22 12:37:08 CET 2011

I have used method 3 with fieldtrip. But I don't think there is an  
easy way, you'll have to create the concatenated dataset yourself and  
tweak some of the fields in your data structure.
In my case it was better to use this method because I am only  
interested in a very short time window, if your time window is long  
enough, it's probably better to use the average method (check van  
Veen et al., 1997, if you haven't already done so).

On 21 Mar 2011, at 20:58, Jean-Michel Badier 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
> Service de Neurophysiologie Clinique. CHU Timone
> 264 Rue Saint-Pierre, 13005 Marseille-France
> _______________________________________________
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