[Eeglablist] ERSP graphs in microvolts (not in dB)?

[arno delorme]

Dear Zach,

> Thanks for the info - I think a lot of us have been wondering about  
> this one ( I actually asked pretty much the same question before  
> your response but it hasn't showed up in the archive yet).  However,  
> the trouble that I am still having is that I'm wondering what is the  
> best way to approach this data for (parametric) statistical  
> analysis.   That is, the default output is in dB which is on a  
> logarithmic scale and thus not appropriate for parametric stats.

Parametric statistics are applicable whenever the data has a  
probability distribution which is close to gaussian. I do not know if  
absolute amplitude has a more gaussian distribution than log power.  
You should test it.

> There is the possibility of nonparametric tests, but my options may  
> be more limited than those of parametric techniques (plus they seem  
> to be somewhat frowned upon in some circles).

Non-parametric ootstrap or permutation test are the norm for single  
subject analysis. For multi-subject analysis, there are applicable  
too. If should test if your data is gaussian to apply a parametric test.

Best,

Arno