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Hi Olga,<br>
<br>
1. i think it should be <br>
-log (1 - (noise_covariance*transfer_matrix / spectral_matrix)). <br>
For details, I recommend this article (if you are using the bsmart
toolbox as implemented in fieldtrip):<br>
Cui et al., 2008, Neural Networks<br>
<a class="moz-txt-link-freetext" href="http://www.ncbi.nlm.nih.gov/pubmed/18599267">http://www.ncbi.nlm.nih.gov/pubmed/18599267</a><br>
<br>
2. i get granger values from 0 to 0.3 in my iEEG data.<br>
I am also not aware of studies getting granger values much higher
than 1 (although there might be some) in real data,<br>
however, simulation studies do show much higher values. <br>
<br>
hope this helps a little,<br>
<br>
best,<br>
Tobias<br>
<br>
<br>
Am 09.11.2011 16:01, schrieb Olga Felsovalyi:
<blockquote
cite="mid:CAHtkvG=ROSTtpcqD1eZ8b70OSv1-hEUuUHKHkMT1-ayfHwH4hA@mail.gmail.com"
type="cite">Hello,<br>
<br>
I am following the connectivity tutorial to perform granger
causality analysis on iEEG data. Please help me understand a few
things:<br>
<br>
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).<br>
<br>
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.
<br>
<br>
Thank you for your help!
<div>
<div>Olga<br>
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<pre wrap="">_______________________________________________
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<a class="moz-txt-link-freetext" href="http://mailman.science.ru.nl/mailman/listinfo/fieldtrip">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a></pre>
</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Tobias Staudigl
Fachbereich Psychologie - ZPR
Postfach ZPR
78457 Konstanz
ZPR, Haus 12
Tel.: +49 (0)7531 / 88 - 5703
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