[Eeglablist] RE : Permutation test for ERSP?

[Andre Achim]

You may consider using either of the attached procedures. Documentation and
reference are in the respective file comments.

André Achim

-----Message d'origine-----
De : eeglablist-bounces at sccn.ucsd.edu
[mailto:eeglablist-bounces at sccn.ucsd.edu] De la part de Tero Hakala
Envoyé : 19 décembre 2007 11:34
À : eeglablist at sccn.ucsd.edu
Objet : [Eeglablist] Permutation test for ERSP?



Hi,

I'm trying to study the differences in ERSP images between two groups of 
subjects. I have calculated grand average ERSPs (for few channels) for 
both groups and need some way to statistically assess the differences 
between these two images. A simple test would suffice at this point.

I have understood that a fairly straightforward way to do this might be 
a permutation test (or bootstrap random draw?)  where one randomly 
assigns subjects to 2 groups, calculates the group averaged ERSP and 
their differences, repeat this for many times and end up with a 
distribution in each TFR-point. Finally use these distributions to 
look for statistically significant points between the ERSP images 
of my two groups.

But before I start to code this myself, I thought that I might ask first 
if someone has already done it and if such a tool is available 
somewhere? At least there's a permutation test in fieldtrip. Is it 
possible to use it easily with EEGLAB-generated data (i.e. just the two 
dimensional ERSP matrices..) (I have no prior experience with fieldtrip).

There was also some discussion about this kind of test in the 
documentation of STUDY structure, but seems that it is not implemented 
yet. E.g. there's a reference to a function called std_erspstatplot but 
no such thing exists. Is there a plan to implement it in the near 
future?

I'd also appreciate any suggestions for other kinds of tests that might 
be useful.

kind regards,
  Tero
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