AW: [Eeglablist] statistics on coherence values

[Sarnthein Johannes]

Hi Gabor,
you can have a look at a possible approach to this problem in our paper
J. Sarnthein, H. Petsche, P. Rappelsberger, G.L. Shaw and A. von Stein "Synchronization between prefrontal and posterior association cortex during working memory tasks in humans", Proceedings of the National Academy of Sciences 95 (1998) 7092-7096. 
Best,
Johannes


-----Ursprüngliche Nachricht-----
Von: eeglablist-bounces at sccn.ucsd.edu [mailto:eeglablist-bounces at sccn.ucsd.edu]Im Auftrag von Stefanics Gabor
Gesendet: Mittwoch, 15. Dezember 2004 16:13
An: eeglablist at sccn.ucsd.edu
Betreff: [Eeglablist] statistics on coherence values


Dear All,

I am analyzing channel cross coherence for 32 channel eeg data, I have the
resulting matrices of the crossf function for all the possible channel
combinations with a 0.05 bootsrap significance mask applied on the prestimulus
baseline. My question is what is the correct statistical procedure to compare
different experimental conditions? In many papers I have read that coherence
values were Fisher-z-transformed before paired Wilcoxon tests on individual
channel-pairs or before ANOVA for a number of channel pairs. So my above
question is manifold:
- Is it necessary to apply Fisher-z-transformation on my data?
- Which statistical test is the optimal? Because if I do the Wilcoxon test,
the significance levels are not corrected for multiple comparisons, but if I
make ANOVA I can test only a subset of the channel pairs to avoid loss of
statistical power of the ANOVA. Is there any way to avoid this trap? 

Thanks for any help and advice in advance!


Gabor Stefanics

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