Hello!
We have an intra-subject design 2 x 2 x 2 (let’s call them factor A, B and C), that is, three factors with two levels each. We want to analyse the EEG data using EEGLAB. However, I think that EEGLAB does not allow to analyse more than 2 factors at the same time, am I right?
If that’s true, we have no problem about calculating the difference between both conditions in factor A; which would remove the factor A. The main hypothesis of the study is that the [influence of] factor A is modulated by an interaction effect B x C (i.e., A x B x C, but we are assuming that only two factors are allowed in EEGLAB).
So, how can I calculate the difference between both conditions in factor A and create a new dataset with that difference? I read that ERPLAB was an option, but I don’t find how to use it.
Thank you!
Alvaro - I am not super-familar with EEGLAB, but in principal, a toolbox does not limit your possibilities of data analysis, right - you can just extract the data from the objects created by EEGLAB and run any statistical analyses on them that you like.
Anyway, I think the easiest way to create a new dataset with the differences is to use one of the old ones as a dummy. When you have two datasets, say EEG1 and EEG2, you go:
EEGdif = EEG1
EEGdif.data = EEG1.data - EEG2.data
gives you the difference values you need in a nice EEGLAB format that you can further process now.
HTH,
Marius
Thanks! I'm trying to handle EEGLAB by myself, but my programming skills are... quite terrible (and it is not as easy as perform a direct subtraction between datasets*). Thus, I was looking for a predefined option in EEGLAB to do that easily. Finally, my labmate create a script to do that automatically (including the importing), so it was solved.
I guess that we could share the code if someone needs it.
* e.g., the datasets have different sizes.
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