[Eeglablist] Question about Coherence

[Don Scott]

Hello,
I have a question about the EEGLAB cross-channel coherence figure.
Coherence is major interest in my contemplated study so quantitative
coherence results are quite important.

I am using EEGLAB v7.1.3.13b, downloaded in compiled form.  After loading a
data set, identifying channel locations, I go to Plot>time-frequency
transforms>Channel cross-coherence and get a figure plotted.  The lower
portion of the figure seems to give spectral power as a function of
frequency and elapsed time during the epoch.  Spectral power seems to be
measured in some unspecified units [-180,180].  What are these units?

Of most interest:  the top portion of the figure is quite mysterious.  What
data are plotted as a joint function of frequency and time? The color bar
units 7.25644e+006 to 2.90258e+007 are also unspecified -- what are they?
A small plot at the left seems to show frequency as a function of
*something* that ranges from 0 to 2

Finally, the small plot at the bottom apparently shows coherence as a
function of time?  The little left-side ordinate label is coh. X 10^6; on
the right it is coh. X 10^7
Is it possible to get quantitative measures of coherence output from
EEGLAB?  Where? How?


I will be grateful for any help.  Maybe there is an explanation with more
detail than is contained in the EEGLAB WIKITORIAL.

Thank you

-- 

Don Scott
(864) 415 - 1795
Dscott8201 at Gmail.Com

*"Although the universe doesn't have an end, it had a beginning in the Big
Bang. One might ask what is before that, but the answer is that there is
nowhere before the Big Bang, just as there is nowhere south of the South
Pole."*
*
*
*--- Stephen Hawking*
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