[Eeglablist] p and F values, difference wave, mean amplitudes

Deniz Dohmen deniz.dohmen at live.de
Fri Aug 29 10:09:38 PDT 2014

Thanks for the quick reply!
However, when I tried it I got an "Reference to non-existent field 'erpdata'" error.
Not really sure why, though.


> Date: Fri, 29 Aug 2014 09:48:48 -0700
> Subject: Re: [Eeglablist]  p and F values, difference wave, mean amplitudes
> From: mdschall at ucsd.edu
> To: deniz.dohmen at live.de
> CC: eeglablist at sccn.ucsd.edu
> Hi Deniz,
> If you are computing T-tests then you don't need an F value, but you'll
> find your T value the same way through EEGLAB. The only way I know how is
> through the command line - you can reference this part of the wiki for
> more information
> http://sccn.ucsd.edu/wiki/Chapter_08:_Command_line_STUDY_functions (under
> plotting stats & receiving results subsection)
> If you are more comfortable using the graphic interface, set up all your
> stat testing parameters first in the GUI, then rather than clicking the
> plot ERPs button, run this command:
> [stats, df, pvals, surrog]=statcond(STUDY.changrp(n).erpdata) - where n=
> the numerical index of the channel of interest. You can find the T-values
> in the variable called stats. Stats has the same number of data points as
> your ERP variable, which are samples, not time points. So if you want to
> see the T-value at latency 300 msec, check out the variable
> STUDY.changrp(n).erptimes. Times are stored in seconds, so look for 0.300,
> and note the column number. Go back and type stats(column number), and
> you'll have the T-value at that time. Do the same for pvals(column number)
> to find the corresponding p value at that time point.
> Hope this helps!
> best,
> Matt
> PhD Candidate, Cognitive Science, UCSD
> Adjunct Professor, Psychology, Chapman University
> https://sites.google.com/site/hazmattneurolab/
> > Dear List,
> >
> > I did all the preprocessing of my data, epoched and created a STUDY with 4
> > conditions for 11 subjects (I'm only comparing conditions a vs b and c vs
> > d, respectively. Thus, two paired t-tests).
> > I also get the graphs and a grey shaded area for the significant
> > latencies. However, I need to get t and p values for my masterthesis.
> > Really struggling to get those.
> > Furthermore, I need to get the mean amplitude of the respective difference
> > waves for the 350-450ms latency (in order to correlate them with another
> > measure.
> > Any advice on how to go about this?
> > I'm under a bit of time pressure and would appreciate any help!
> >
> > Cheers,
> > Deniz
> >
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