[Eeglablist] comparing condition and group ERP's from a STUDY

Sun Oct 19 18:06:07 PDT 2008

Hi Arno, thanks for your reply.

The weird thing is, I'm certain that all your points below are true.
Both conditions are present in all subjects, and the group really is a
group (ie groups '1' and '2' have different subjects - children vs
adults, and are not ways to sneak in extra conditions).

Just to be sure, I wrote a short script to save the EEG.setnames,
EEG.group, EEG.condition, EEG.ntrials, pnts, srate, xmin and xmax for
all the sets in the Study to a csv file, and all was correct.

% script for extracting the number of trials of each stimulus, for each
% subject in a STUDY.
%STUDY must be currently open
% loop over sets in study.

nsets = size(STUDY.datasetinfo,2)

%make an empty matrix to fill up with the data
%rows = sets
output = zeros(nsets, 8);

for currentset = 1:nsets;
    csetname = EEG(currentset).setname;
    ID = str2num(csetname(2:4));
    output(currentset,1) = ID;
    output(currentset,2) = str2num(EEG(currentset).group) ;
    output(currentset,3) = str2num(EEG(currentset).condition);
    output(currentset,4) = EEG(currentset).trials ;
    output(currentset,5) = EEG(currentset).pnts ;
    output(currentset,6) = EEG(currentset).srate ;
    output(currentset,7) = EEG(currentset).xmin ;
    output(currentset,8) = EEG(currentset).xmax ;
end

Results here if interested
http://spreadsheets.google.com/ccc?key=pMWrciDbEoFRAgnrYtXy9MQ
<http://spreadsheets.google.com/ccc?key=pMWrciDbEoFRAgnrYtXy9MQ&inv=hinn
esbrown at gmail.com&t=4926724069117154563&guest> 

The other weird thing is that every other plotting button works
perfectly well, I can see Spect, ERSP, and ITC plots for both conditions
and groups, which makes me think the data must be OK, as I guess all
these measures are being calculated from the same data..?

And all the electrodes are interpolated - I ended up using v6.01 just to
do the electrode interpolation, then switching back to 6.03b(oct2008) to
pre-calc all the channel measures.  Selecting the individual setfiles
and plotting ERP's also works fine, for both groups and condition types,
so I dont think the data is missing or wrongly arranged.  Any other
hints?

Many thanks!

Hamish Innes-Brown 
Senior Research Officer 

The Bionic Ear Institute 
Auditory Clinical Neuroscience Unit 
c/o St Vincents Hospital 
6th Floor Daly Wing, 
35 Victoria Pde, Fitzroy Vic 3065 
Tel: +61 3 9288 3523 
Fax: +61 3 6997 7518 

________________________________

From: eeglablist-bounces at sccn.ucsd.edu
[mailto:eeglablist-bounces at sccn.ucsd.edu] On Behalf Of arno delorme
Sent: Saturday, 18 October 2008 9:58 PM
To: Hamish INNES-BROWN
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] comparing condition and group ERP's from a
STUDY

Dear Hamish, 

some more information about groups and conditions. Optimally:

- All conditions are supposed to be present in all subjects. If not, the
program should still work but might lead to the empty plots you are
seeing them right now.
- Groups are supposed to be for different subjects or different sessions
(different ICA decomposition for sure). Using groups within the same
subjects (to define a second condition) might work but not always. This
is pushing the limits of the program.
- You should interpolate missing electrodes. Once more, if you do not do
that, the program should work but the average will take into account
different subjects at each channel location.

We are working on these limitations. You will be able to select several
conditions and/or groups. 

Best,

Arno

On 14 oct. 08, at 07:35, Hamish INNES-BROWN wrote:

	Hi EEGLAB list. 

	I'm currently trying to track down the source of a problem i
have plotting condition and group ERP's from the STUDY channel measures
menu.

	I have all the 'group' and 'condition' data loaded into the
EEG.group and EEG.condition.  The correct group and condition numbers
pop up in the study info window when all the subjects are loaded into
the study..  In EEG.group and EEG.condition the values are strings (but
numerals).  I have groups '1' and '2', and conditions '111' and '122'.

	The study looks like this 
	>> STUDY 
	STUDY = 
	           name: 'Study1' 
	    datasetinfo: [1x58 struct] 
	        cluster: [1x1 struct] 
	        changrp: [1x63 struct] 
	           task: '' 
	          notes: '' 
	       filename: 'STUDY_ALL.study' 
	       filepath:
'D:\_PROJECTS\_FB\_ANALYSIS\__EEGLAB\SET\08STUDY_ALL\' 
	        history: [1x3126 char] 
	        subject: {1x29 cell} 
	          group: {'1'  '2'} 
	        session: [] 
	      condition: {'111'  '122'} 
	         setind: [2x29 double] 
	            etc: [1x1 struct] 
	       preclust: [1x1 struct] 
	          saved: 'yes' 

	Now, when plotting the channel measures, I select "plot
conditions on the same panel", and get two plots as expected.  The first
(group '1') has two lines, as expected.  One is labelled '111' and the
other '122'. All OK.  However underneath there is an empty plot,
labelled '2', but with no lines.

	I thought this might be somehow a fault in my data or the way
the conditions and groups are entered (maybe they should be numbers, not
strings?) so I tried loading the example data (5subjects.zip), and added
a group variable.  Same problem however.

	Anyone had any luck with this before? 

	Many thanks 

	Hamish Innes-Brown 
	Senior Research Officer 

	The Bionic Ear Institute 
	Auditory Clinical Neuroscience Unit 
	c/o St Vincents Hospital 
	6th Floor Daly Wing, 
	35 Victoria Pde, Fitzroy Vic 3065 
	Tel: +61 3 9288 3523 
	Fax: +61 3 6997 7518 

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