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

[Zachary Moran]

Hi Arno,

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.  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).

Is using the "  'baseline', NaN  " option the solution to this problem?  I'm
interested in comparing event-related changes in spectral amplitude - will
the matrix for a baseline-intact ERSP array provide me with these values?
If not, do you have any recommendations for how to go about converting dB
ERSP matrices to those which would be amenable to parametric statistics?

Many thanks!!

Zach Moran

Grad Student
University of California-Los Angeles
Lab for Clinical Affective Psychophysiology


On Thu, Sep 11, 2008 at 7:21 AM, arno delorme <arno at ucsd.edu> wrote:

> Dear Maria,
>
> no there is no way to plot microV (since this is a spectral
> decomposition). To plot the time-frequency decomposition without
> removing the baseline, try entering 'baseline', NaN.
>
> Hope this helps,
>
> Arno
>
> On 14 juil. 08, at 10:22, Maria Kharitonova wrote:
>
> > Hello,
> >
> > I'm learning how to make time-frequency plots using EEGLAB. I was able
> > to make the plots using the timef() function. However, I noticed that
> > the scale is in dB, and not in microvolts. Is there any way to make
> > the ERSP plots using the microV (and not dB) scale? I searched the
> > help files and the archives but could not find anything.
> >
> > Thank you in advance!
> >
> > Maria Kharitonova
> >
> >
> > **********************************
> > Maria Kharitonova, M.A.
> > Department of Psychology
> > University of Colorado, Boulder
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