[Eeglablist] Interpreting std_erspplot output in terms of design

[Dominic Roe]

Dear EEGLAB community,

I am kindly seeking some help for some confusion I am experiencing when
trying to interpret the output of pgroup, pcond and pinter variables from
the std_erspplot function.

I have a 2x2 mixed design, 1 between participants group: training group and
control group. 1 within participants: pre-test and post-test.

The study setup is as follows:
1st independent variable: group, values (Training-Control)
2nd independent variable: condition, values (Pre-Post)

I have created my study design in eeglab study and computed ERSP. I am
interested in channels C3 and C4, and the differences between the groups at
the different time points in these channels and the differences between the
time points in these groups.

I have ran

[STUDY erspdata ersptimes erspfreqs pgroup pcond pinter ] =
std_erspplot(STUDY,
ALLEEG, 'channels', {C3, C4}, 'design',1);

In the output variables I then have erspdata as a 2x2 cell array, with each
cell containing a 4-D matrix.

pgroup as 1x2 cell array, with each cell containing 56x200x2 - i am
assuming        freqs x timepoints x channels.

pcond as 1x2 cell array, with each cell containing 56x200x2 - i am
assuming        freqs x timepoints x channels.

pinter as 1x3 cell array, with each cell containing 56x200x2 - i am
assuming        freqs x timepoints x channels.

I am struggling to interpret what each cell in these variables mean, I am
wanting to look at differences between
1. Training group and control group at the pre-test,
2. Training group and control group at the post-test
3. Training group pre-test and training group post-test
4. Control group pre-test and control group post-test

At both channels C3 and C4.

Any help would be greatly appreciated.

Kind regards,
Dominic Roe

PhD Student FHEA
Psychology Department
University of Sheffield
ICOSS Building