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Hi Vijay<br>
<br>
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)<br>
<br>
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).<br>
--> there is a tutorial which show a case very similar .. it
should be easy enough to do on your data<br>
<br>
Cyril<br>
<br>
<br>
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<div class="headerdisplayname" style="display:inline;">Subject:
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[Eeglablist] Performining the t-test and highiliting the
area</td>
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<div class="headerdisplayname" style="display:inline;">From:
</div>
Vijay Narne <a class="moz-txt-link-rfc2396E" href="mailto:vijaynarne@gmail.com"><vijaynarne@gmail.com></a></td>
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<div class="headerdisplayname" style="display:inline;">Date:
</div>
11/05/2012 05:54</td>
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<div class="headerdisplayname" style="display:inline;">To: </div>
<a class="moz-txt-link-abbreviated" href="mailto:eeglablist@sccn.ucsd.edu">eeglablist@sccn.ucsd.edu</a></td>
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<br>
<div>Dear List,</div>
<div> </div>
<div> 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.</div>
<div> </div>
<div>Thanking you</div>
<div> </div>
Vijay<br>
<br>
<br>
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<div class="headerdisplayname" style="display:inline;">Subject:
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Re: [Eeglablist] Performining the t-test and highiliting the
area</td>
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<td>
<div class="headerdisplayname" style="display:inline;">From:
</div>
Alex Davila <a class="moz-txt-link-rfc2396E" href="mailto:axel.1963@hotmail.com"><axel.1963@hotmail.com></a></td>
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<div class="headerdisplayname" style="display:inline;">Date:
</div>
14/05/2012 20:26</td>
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<div class="headerdisplayname" style="display:inline;">To: </div>
<a class="moz-txt-link-rfc2396E" href="mailto:vijaynarne@gmail.com"><vijaynarne@gmail.com></a>,
<a class="moz-txt-link-rfc2396E" href="mailto:eeglablist@sccn.ucsd.edu"><eeglablist@sccn.ucsd.edu></a></td>
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<br>
Dear Vijaya,<br>
<br>
I assume that your two conditions are run on the same participants
(repeated measures). Then, what you need to do is just this:<br>
<br>
1. Define the variable D = C - I<br>
<br>
where C: your variable for the congruent condition and I: your
variable for the incongruent condition.<br>
<br>
2. Calculate the mean M and the sample standard deviation S for D.<br>
<br>
3. Calculate t = M/(S/rootsquare(N))<br>
<br>
where N: your number of participants.<br>
<br>
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.<br>
<br>
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.<br>
<br>
6. Of course, before getting this data, you need to apply the
standard averaging procedure to extract the ERP signal from the
noise.<br>
<br>
All the best,<br>
<br>
Alex. <br>
<pre class="moz-signature" cols="72">--
Dr Cyril Pernet,
Academic Fellow
Brain Research Imaging Center
<a class="moz-txt-link-freetext" href="http://www.bric.ed.ac.uk/">http://www.bric.ed.ac.uk/</a>
Division of Clinical Neurosciences
University of Edinburgh
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU
Scotland, UK
<a class="moz-txt-link-abbreviated" href="mailto:cyril.pernet@ed.ac.uk">cyril.pernet@ed.ac.uk</a>
tel: +44(0)1315373661
<a class="moz-txt-link-freetext" href="http://www.sbirc.ed.ac.uk/LCL/">http://www.sbirc.ed.ac.uk/LCL/</a>
<a class="moz-txt-link-freetext" href="http://www.sbirc.ed.ac.uk/cyril">http://www.sbirc.ed.ac.uk/cyril</a>
</pre>
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