[Eeglablist] Is short epoch necessary for all types of experiment ?

[Vibra Lab]

Dear Colleagues of EEGLAB,

I need your help to strengthen my understanding so that it can sharpen my
analysis.

Let me describe my study. A person is given 4 sections (in total around 60
minutes for all sections for each participant). For each section,
participant is given various questions that they need to answer. i.e. it's
like a conversation. Due to the nature of the experiment, the length of
each section for each participant varies. For instance, for section *one *(for
4 participants) there are *4 different lengths* of time window (10 minutes,
15 minutes, 20 minutes, and 25 minutes). In relation to that, I have
several questions as follow :

1. Can I just *directly *analyze such full length of time window
(considering after pre-processing the data), *e.g. 10 minutes*, instead of
dividing them into 30 - 40 epochs out of 10 minutes  ?

2. Something that I still don't get the reason behind epoch is, *why do we
have to create data into epochs ?* since the tutorial always uses epoch. I
really appreciate if you could give me such reasoning for this. Since the
beginning I learn ERP I still don't understand the significance of creating
epoch.

3. Why is the duration of epoch is always short ? I rarely find epoch for
more than 1 minute.

4. If I need to create epochs (30 - 40), *3 seconds each*, how can I do
that ? since I have only 4 markers (considering there are 4 sections for
the whole experiment for each participant) in my original data ?

I would like to thank you in advanced for your help. Look forward to your
answer.

Sincerely,
Ihshan
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