[Eeglablist] Statistics in EEGlab

[Arnaud Delorme]

Dear Stefon,

yes you are correct. When you have a mixed design (paired) x (unpaired), EEGLAB will use (unpaired) x (unpaired) so it is better to use surrogate statistical approaches. There is a warning on the command line that indicates that EEGLAB does so if I remember well. When using surrogate methods, EEGLAB will use a balanced ANOVA approach (unpaired x unpaired) but data shuffling will be computed according to the pairing selection. In the surrogate case, ANOVA is simply use as a metric of distance for your design, so it is not (as) critical to use the correct ANOVA method.

Ideally, we would use the correct repeated ANOVA function for mixed design (paired x unpaired) but there is no such function in Matlab to our knowledge. The only function available is in R. David Groppe (copied to this message) would know more about this. We are planning in the long run to automatically bridge some statistics from Matlab to R. If anybody wants to help, let us know.

Best,

Arno

On Jun 20, 2012, at 7:29 PM, Stefon van Noordt wrote:

> Dear colleagues,
> 
> If the 'parametric' option is selected, does the study module treat a  
> 2 (paired) x 2 (unpaired) design as a mixed-ANOVA with repeated  
> measures?
> 
> Comparing differences in inter-trial coherence with a 2 (feedback type  
> - paired
> statistics) x 2 (gender - unpaired statistics) study design seems to  
> produce the same results as when both variables are set to be paired  
> statistics (i.e., for the purpose of testing the outcome, setting  
> gender as paired instead of unpaired).
> 
> Thanks for your time.
> 
> Best regards,
> Stefon van Noordt
> 
> 
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