[Eeglablist] Performining the t-test and highiliting the area

Thu May 24 00:54:43 PDT 2012

Hi David

LIMO is not just a 2 levels mass univariate, it is a full hierarchical 
GLM, ie you can do any stats you want, from t tests to repeated measure 
ANOVA
+ 2 level relies on robust statistics (no assumption of normality across 
subjects)
+ multiple comparisons has been validated (for most tests) to be a 
nominal level using spatio-temporal clustering
+ various tools for robust averaging, robust differences (for eg a MMN)

and more to come soon(ish)

Cyril


> Hi Vijay,
>    The Mass Univariate Toolbox EEGLAB plugin similarly can do the 
> large number of t-tests you want with savvy corrections for multiple 
> comparisons:
>
> http://openwetware.org/wiki/Mass_Univariate_ERP_Toolbox
>
> I think the main difference between it and LIMO are the visualizations 
> and graphical user interfaces it provides for exploring effects.
>    cheers,
>       -David
>
> On Wed, May 16, 2012 at 2:16 PM, cyril pernet <cyril.pernet at ed.ac.uk 
> <mailto:cyril.pernet at ed.ac.uk>> wrote:
>
>     Hi Vijay
>
>     Alex proposal is fine although that assumes that you are happy
>     loosing information related to trial variance and also you are not
>     bothered by multiple comparisons (doing that many t-test will
>     automatically lead to some false positives)
>
>     as an alternative, you can do the statistical analysis with LIMO
>     EEG (EEGlab toolbox to download) - that will allow you to model
>     congruent and incongruent conditions per subjects and then test
>     across subjects for a significant differences (in fact across all
>     electrodes and time frames and using clustering to control the
>     false positive rate).
>     --> there is a tutorial which show a case very similar .. it
>     should be easy enough to do on your data
>
>     Cyril
>
>
>     Subject:
>     [Eeglablist] Performining the t-test and highiliting the area
>     From:
>     Vijay Narne <vijaynarne at gmail.com> <mailto:vijaynarne at gmail.com>
>     Date:
>     11/05/2012 05:54
>
>     To:
>     eeglablist at sccn.ucsd.edu <mailto:eeglablist at sccn.ucsd.edu>
>
>
>     Dear List,
>                 I am Vijaya Kumar Narne, PhD. We are running the
>     experiments on N400. We would like to compare ERP of the congruent
>     and incongruent condition. We are intrested in running t-test and
>     highliting the area of N400 in EEGLAB.  As we are new to EEGLAB,
>     if any one help us do this.
>     Thanking you
>     Vijay
>
>
>     Subject:
>     Re: [Eeglablist] Performining the t-test and highiliting the area
>     From:
>     Alex Davila <axel.1963 at hotmail.com> <mailto:axel.1963 at hotmail.com>
>     Date:
>     14/05/2012 20:26
>
>     To:
>     <vijaynarne at gmail.com> <mailto:vijaynarne at gmail.com>,
>     <eeglablist at sccn.ucsd.edu> <mailto:eeglablist at sccn.ucsd.edu>
>
>
>     Dear Vijaya,
>
>     I assume that your two conditions are run on the same participants
>     (repeated measures). Then, what you need to do is just this:
>
>     1. Define the variable D = C - I
>
>     where C: your variable for the congruent condition and I: your
>     variable for the incongruent condition.
>
>     2. Calculate the mean M and the sample standard deviation S for D.
>
>     3. Calculate t = M/(S/rootsquare(N))
>
>     where N: your number of participants.
>
>     4. Depending on your hypothesis, compare your calculated t with a
>     one tail or two tail table t-student value. I'd suggest to use an
>     alpha value identical to those available in the relevant literature.
>
>     5. As you're interested in the N400 value, I assume you
>     may extract it from your ERP data of potentials across the time
>     domain where you may identify local maxima and minima for each
>     participant.
>
>     6. Of course, before getting this data, you need to apply the
>     standard averaging procedure to extract the ERP signal from the noise.
>
>     All the best,
>
>     Alex.
>
>     -- 
>     Dr Cyril Pernet,
>
>     Academic Fellow
>     Brain Research Imaging Center
>     http://www.bric.ed.ac.uk/
>     Division of Clinical Neurosciences
>     University of Edinburgh
>     Western General Hospital
>     Crewe Road
>     Edinburgh
>     EH4 2XU
>     Scotland, UK
>
>     cyril.pernet at ed.ac.uk  <mailto:cyril.pernet at ed.ac.uk>
>     tel:+44(0)1315373661  <tel:%2B44%280%291315373661>
>     http://www.sbirc.ed.ac.uk/LCL/
>     http://www.sbirc.ed.ac.uk/cyril
>
>
>     The University of Edinburgh is a charitable body, registered in
>     Scotland, with registration number SC005336.
>
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>
>
>
> -- 
> David Groppe, Ph.D.
> Postdoctoral Researcher
> North Shore LIJ Health System
> New Hyde Park, New York
> http://www.cogsci.ucsd.edu/~dgroppe/ 
> <http://www.cogsci.ucsd.edu/%7Edgroppe/>


-- 
Dr Cyril Pernet,

Academic Fellow
Brain Research Imaging Center
http://www.bric.ed.ac.uk/
Division of Clinical Neurosciences
University of Edinburgh
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU
Scotland, UK

cyril.pernet at ed.ac.uk
tel: +44(0)1315373661
http://www.sbirc.ed.ac.uk/LCL/
http://www.sbirc.ed.ac.uk/cyril


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