[Eeglablist] bad channel rejection based on spectrum (pop_rejchan, spectopo issue)

[Jerry Zhu]

Dear all,
Since version 12, EEGLAB has a new method of bad channel rejection based on
spectrum. We found it is very cool! However, during the process, I found
the frequency range seems irrelevant. Not sure whether it is a bug or
something else.

Here is what I did (in EEGLAB v13.3.2):
Tools-->Automatic channel rejection-->Measure to use: spectrum-->check the
normalization off-->absolute threshold -50 50
The frequency range is the tricky part: I can leave it empty (by default it
uses [1 EEG.srate/2]), or put [1 55], or [55 65]. They all give me the same
calculated measures. Critically I check the code of pop_rejchan:

measure1 = pop_spectopo(EEG, 1, [], 'EEG' , 'freqrange', [1 125],
'plot','off');
measure2 = pop_spectopo(EEG, 1, [], 'EEG' , 'freqrange', [55 65],
'plot','off');

Run them and check with isequal(measure1, measure2). They are the same!

As far as I know, if I use different freqrange, the result should be
different with my dataset.

Maybe some other users can confirm this. Thanks for your help!

Cheers,
Jerry

--
Jian Zhu, M.A.
Brain and Cognitive Sciences
Department of Psychology
Southern Illinois University Carbondale
Web: http://zhupsy.com

We have two halves in the brain: left and right. Nothing is right in the
left. Nothing is left in the right.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20140716/f40b290b/attachment.html>