[Eeglablist] Unequal group size and STUDY use

[Hamish INNES-BROWN]

Interesting, it's working really well for me - I'm very glad!
 
I did have to ensure that the interpolation was done correctly though.
For me this meant using the stable v6.01 to do JUST the interpolation,
saving the STUDY, and then going back to the Oct08 version to
pre-calculate my channel measures.  Then the plotting of channel
measures with unequal group sizes (and I also have two conditions) works
fine as far as I can see.
 
I never did work out why the interpolation didn't work correctly in the
newer versions.  I tried many different parameters using std_interp,
eeg_interp as well as the menu system, and always ended up with an error
(griddata error previously reported).
 
Anyway that's what worked for me - do interpolation in the stable
version of eeglab (v6.01), then calculate channel measures in the oct08
version, and then plotting will work.  Probably there is an easier way
:)
 
It looks like what you did should have worked though, are you definitely
using the edited version of std_erpplot.m?  I have a few different
eeglab directories on my PC and it's easy to start up from the wrong
one..
 

Hamish Innes-Brown 
Senior Research Assistant 

The Bionic Ear Institute 
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: Hilla Jakoby [mailto:jakobyhi at yahoo.com] 
Sent: Tuesday, 2 December 2008 2:59 AM
To: Hamish INNES-BROWN; arno delorme
Cc: eeglablist at sccn.ucsd.edu; Michael Stevens
Subject: Re: [Eeglablist] Unequal group size and STUDY use


 
Dear all,
 
I've tried to use the new std_erpplot.m function with an unequal number
of subjects of each group (25 versus 29) and the same error message was
generated when trying to plot their ERPs as before (using the old
function). I've interpolated all datasets beforehand to 65 electrodes
(using eeg_interp(EEG, chanlocs,'invdist'). was I right in doing so? 
On equal group sizes STUDY works well.
Is there another solution for the problem, other changes to be done?
Many thanks, Hilla
 
 
Ph.D. student
Gonda brain reseach center, 
Bar Ilan Universiy, Israel
 
 


--- On Sun, 11/30/08, arno delorme <arno at ucsd.edu> wrote:


	From: arno delorme <arno at ucsd.edu>
	Subject: Re: [Eeglablist] Unequal group size and STUDY use
	To: "Hamish INNES-BROWN" <HINNES-BROWN at bionicear.org>
	Cc: eeglablist at sccn.ucsd.edu, "Michael Stevens"
<msteven at harthosp.org>
	Date: Sunday, November 30, 2008, 9:40 PM
	
	
	Dear Michael and Hamish,
	
	thanks for reporting the problem. This issue arises due to the
complexity of
	the scheme implemented to handle scalp map plotting in the case
of subject with
	different number of channels. This scheme was currently
enforcing to have groups
	of the same size. To fix this problem, I have decided to enforce
interpolation
	so that all subject will need to have the same number of
channels (or at least
	subset of channels when plotting scalp maps). Scalp maps where
the different
	channels average different numbers of subjects do not make much
sense anyway.
	There has also been at least two people reporting plotting
problems after
	interpolating data, although I have not yet myself been able to
reproduce the
	problem. I hope the current fix will solve this problem too.
	
	I have reprogrammed the attached std_erpplot.m function so that
it can handle
	groups of different sizes (although be sure to interpolate
missing channels).
	Please let me know if this fixes your problems (just replace
this function in
	the eeglabxxx/functions/studyfunc/ folder) and it will be
integrated in the
	EEGLAB monthly release. This message was forwarded to the list
because it is of
	global interest and also because it depicts a problem that is a
major current
	limitation for most users. In general though, please use the
Bugzilla database
	for reporting problems.
	
	Best,
	
	Arno
	
	ps: For interpolation, there is currently a non-documented bug:
if you
	interpolate channels when pre-computing ERPs and then go back to
the pre-compute
	GUI to compute ERSP without interpolation, the function will
crash. This is
	because all measure have to be consistent in terms of
interpolation. As
	described above, the future function will enforce interpolation
(which is
	relatively fast). In case the function crashed for you, erase
all measure data
	files (*.daterp, *.datersp, *.datspec, *.datitc), and type on
the command line
	STUDY.changrp = []; then call back the pre-computing interface.
	
	
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