Hi all,
I have a doubt with regards to mscohere function output in matlab. I have 64 channel EEG data to extract coherence data for. Which means I would need a 64×64 matrix output for a particular frequency band say 8 to 13 Hz. I went through the documentation of mscohere function sveral times. One thing that I saw was that mscohere Cxy part can either be a vector, matrix or 3-D array. When I use the following code to calculate coherence between just two channels, channel 20 and channel 50, I get a 501×1 single column vector:
ch1 = 20;ch2 = 50;window = 2*EEG.srate; % create 2 sec epochs
noverlap = 0; % overlap
nfft = window*2; % zero-padding factor 2 for smoothing
fs = EEG.srate;[Cxy,F] = mscohere(EEG.data(ch1,:),EEG.data(ch2,:),window,noverlap,nfft,fs);CxyCxy = 501×1 single column vector 0.0003 0.0060 0.0042 0.0003 0.0047 % I copied the first few values only to show the output I am getting
Can someone explain this output to me? Are these coherence values between two channels at 501 different frequency points (I'm just guessing. Not sure!)? Also, how do I input the frequency band of my interest like 8-13 Hz and calculate coherence just for that? Are there more steps in calculating coherence in matlab? How do I get a single value (between 0 to 1) for channel 20 x channel 50 coherence for 8-13 Hz frequency band?
I hope my question makes sense. Please let me know if I need to explain anything further.
Thanks!
Satya
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