[Eeglablist] common baseline in std_ersp with 2 independent variables

[Anna-Antonia Pape]

Hello everyone.

I want to compute the ERSP on the component level in a study with 2 
independent variables with 2 levels each.
So it's a 2x2 design, say    L vs R   x   + vs -  , i.e. 4 
condition-pairs (L+, L-, R+, R-)
To save space on my disk, i have all conditions in one dataset, not 
separate datasets.
I would like the baseline to be the same for all 4 conditions, e.g. the 
mean of the 4 conditions. (I don't know whether this is sensible).

Anyway, I came up with two ideas to get there:

1)  I tried using 'commonbase' as a value added in the pop_precomp GUI.
But if i understand it correctly by looking at the code of pop_precomp, 
the way pop_precomp calls std_ersp, std_ersp calculates the ERSPs for 
each condition-pair individually, i.e. in this fashion:

for subject
    for condition-pair
       for component
                          std_ersp()
       end
    end
end

So it seems to me as if i cannot use 'commonbase', if I want to have the 
same baseline for all four conditions. Is this correct?


2) I tried entering the precalculated mean of all the conditions via the 
pop_precomp GUI window with the 'powbase' key.
It seems to me that the 'powbase' key somehow gets lost on the way and 
is not handed over to std_ersp. Is this is correct?

I highly appreciate any comments on this.

Cheers from Tübingen,
Anna

-- 
Anna-Antonia Pape, M.Sc. of Neural  & Behavioral Science

email: aa.pape at iwm-kmrc.de
phone: +49 7071 979 301

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