[Eeglablist] Inquiry on averaging

[Dwight Peterson]

Hi Ganesh,

            I would start by importing your data for one subject (in
whatever format it is in, e.g., matlab array, etc.) into EEGLAB, then
adding channel information (e.g., labels, topographic location info if you
have it), adding your events (that correspond to your 6 different
conditions.

            I have recently switched to using ERPLAB (another toolbox that
you can download for free that will run within the same GUI as EEGLAB)
after implementing these first few steps in EEGLAB.    After you have your
dataset created and saved in EEGLAB, you can use ERPLAB to create an
eventlist (basically a txt file) that has your condition information (or
unique identifiers corresponding to your 6 conditions for example).  This
will store your conditions of interest as "bins" meaning ERPLAB will mark
your event types indicated in the eventlist and store them in separate bins
(read up on the tutorial/manual online for specifics).  Then you can
extract bin based epochs (e.g., -200 ms (pre stimulus onset) to say 1000 ms
post stimulus onset).   You can also do things with filtering (either the
raw EEG data or your averaged ERP data).  Then you can do artifact
detection (a variety of functions are available within ERPLAB tools for
this).  Then you can compute averages based on your epochs.  Then you
should have (in theory)  6 different averaged ERP waveforms (corresponding
to each of your conditions) for Subject 1.  Then you can repeat these steps
for each subjects data and then use the Create Grand Average Waveform
within ERPLAB once all your datasets are processed and loaded into ERPLAB
and create a grand averaged waveform for each condition across all of your
subjects.  There are a lot of advantages to ERPLAB in terms of plotting of
the waveforms as well, so that is why I suggest using EEGLAB for the first
few steps and then adopting ERPLAB for epoching, artifact detection,
averaging, and plotting.


Good luck!  Hope this helps!

--Dwight--

On Wed, Mar 27, 2013 at 4:33 AM, coolac0017 <coolac0017 at gmail.com> wrote:

> HI,
> I have six conditions, i have to average data of multiple subjects
> How to do this in EEGLAB
> Thank you
>
>
> --
> Ganesh.A.C
> Lecturer,
> Dr M.V.Shetty College of Speech & Hearing,
> Mangalore,
> Ph no 09738405101
>
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-- 
Dwight J. Peterson, M.A.
Graduate Assistant
Cognitive and Brain Sciences
Department of Psychology/296
Memory and Brain Laboratory
University of Nevada, Reno
Reno, NV 89557
Cellular: 319-231-8596
Laboratory: 775-682-8667
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