[Eeglablist] Question about time-frequency analysis

[Michael Stevens]

Hi folks,

I'm trying to use the EEGLAB time-frequency analysis to do a simple single-trial FFT on EEG data sampled at 500 Hz during an auditory oddball task.  I've epoched 1000 msec trials around the targets and successfully called the newtimef.m function to get out 26 frequency bins.  However, I'd like to look at 'absolute power', not 'dB'.  The function provides an optional input called 'outputformat' which can be set to provide 'old' output in 'absolute amplitude'.  I'm pretty sure this is what I want (right?).

However, my immediate problem is that when I run the code now specifying 'old' output format, it gives me an error:

??? Error using ==> mpower
Matrix must be square.

Error in ==> newtimef at 1750
	mbase = 10^(mbase/10);


So, I'm wondering if I'm specifying something with the code that the 'old' code can't handle?  I've copied the actual function call below if anyone can help me.

[ersp,itc,powbase,times,freqs,erpsboot,itcboot] = newtimef(DATA, 500, [-24 976],500,0,'padratio',1,'winsize',256,'outputformat','old');


Many thanks for any suggestions or fixes.  I've got the whole analysis scripted up to run, but can't get past this problem.

Best regards,
Mike


Michael C. Stevens, Ph.D.

Director, Child and Adolescent Research
The Institute of Living / Hartford Hospital

Director, Clinical Neuroscience & Development Laboratory
Olin Neuropsychiatry Research Center

Assistant Clinical Professor of Psychiatry
Yale University School of Medicine

Contact Information:
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ONRC, Whitehall Building
Hartford, CT  06106

Tel: (860) 545-7552
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