[Eeglablist] .datersp file contents question

[Steven Pillen]

Hello, EEGLAB list.

We were running an ERSP study, and we had some questions about the output
files.

When we load the contents of a .datersp file with the function, "m =
importdata('filename.datersp'), the m struct contains two elements for each
channel:

 chan1_ersp: [100x200 single]
 chan1_erspbase: [1x100 single]

I figure that the two dimensions of the plain "ersp" correspond to
frequency and time respectively, because they are the same size as the
m.freqs and the m.times branches.  What I am unsure of is what exactly I am
looking at in the contents of these files.  Can anyone tell me what the
numbers in those branches represent?

I was hoping, for instance, that the values in the "ersp" branch would
contain a table of the spectrum values for each cross-section of frequency
and time, but it looks like maybe they've had some kind of normalization
applied to them, like maybe a logarithmic function or something.  I want to
be sure what I'm looking at before I attempt any statistical analysis.

Also, what is the relationship between the "ersp" and the "erspbase"?

Thank you,
Steven Pillen
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