[FieldTrip] Granger Causality

[Tobias Staudigl]

Hi Olga,

1. i think it should be
-log (1 - (noise_covariance*transfer_matrix / spectral_matrix)).
For details, I recommend this article (if you are using the bsmart 
toolbox as implemented in fieldtrip):
Cui et al., 2008, Neural Networks
http://www.ncbi.nlm.nih.gov/pubmed/18599267

2. i get granger values from 0 to 0.3 in my iEEG data.
I am also not aware of studies getting granger values much higher than 1 
(although there might be some) in real data,
however, simulation studies do show much higher values.

hope this helps a little,

best,
Tobias


Am 09.11.2011 16:01, schrieb Olga Felsovalyi:
> Hello,
>
> I am following the connectivity tutorial to perform granger causality 
> analysis on iEEG data.  Please help me understand a few things:
>
> 1. Please clarify exactly what the output values of the granger matrix 
> represent. If I understand correctly, it is the log(variance of 
> predicted time course/variance of actual time course).
>
> 2. What range of values should I be getting for granger causality for 
> iEEG data? I am getting values ranging from 0 to 2.5. Values I see 
> reported in papers seem to report peaks barley higher than 1.
>
> Thank you for your help!
> Olga
>
>
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-- 
Tobias Staudigl
Fachbereich Psychologie - ZPR
Postfach ZPR
78457 Konstanz
ZPR, Haus 12
Tel.: +49 (0)7531 / 88 - 5703

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