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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>Dear Matteo,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'>
<p class=MsoNormal><span lang=EN-US>I have two questions regarding statistical
tests: first one regarding coherence differences, second one pertaining testing
inter-trial coherence.<br>
<br>
</span>We are analysing MEG data from an auditory experiment with 5 subjects.
We considered the deviant stimulus as the only stimulus in the recordings,
while the standard one was considered as baseline activity.<br>
<br>
We analysed the TFR data in both designs: within-trial and within-subject using
respectively "actvsblT" and "depsamplesT" statistics. In
both cases we compared a time interval extracted from the baseline versus a
time interval from the deviant stimulus response.<br>
<br>
We wish to assess coherence differences using "indepsampleZcoh"
statistic in both single-subject and multiple-subject cases. In a previous <a
href="https://listserv.surfnet.nl/scripts/wa.cgi?A2=ind1004&L=FIELDTRIP&D=0&P=10812">post</a>
Dr. Maris replied that this statistic only works in a between-trial design (for
single-subject case) and suggested to compare the different conditions as they
were un-paired.<br>
We exploited this idea for the single-subject case and we would like to know if
it is legitimate to extend the same idea for the multiple-subject situation?<br>
<br>
<span style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>In the multiple-subject situation, you should first calculate
the two coherences (one for the deviant stimulus and one for the baseline
condition) for every subject. These coherences should be compared using
depsamplesT (and not using indepsamplesZcoh, which only works for a single-subject
study). I’m fairly sure that the testing of coherence in a multiple subject
study has already been addressed in the Fieldtrip discussion list. I think it
was Jan-Matthijs Schoffelen who gave a extensive description on how to do it.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US><br>
Furthermore we would like to know if there is a way to test inter-trial
coherence differences in Fieldtrip?<br>
In a previous </span><a
href="https://listserv.surfnet.nl/scripts/wa.cgi?A2=ind0803&L=FIELDTRIP&D=0&P=180"><span
lang=EN-US>post</span></a><span lang=EN-US> Stephan suggested how to deal with
the problem; is it already implemented?<br>
</span><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif"'><br>
<span style='color:#1F497D'>If it has been implemented, I’m not aware of
it. However, if you are a little bit proficient in Matlab programming, you can write
you own statfun and have Fieldtrip apply it to your data. By debugging a
statistical analysis that uses a built-in statfun, you can learn how the
algorithm works.<o:p></o:p></span></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>Good luck,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'>Eric Maris<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Thanks in advance for your time<br>
<br>
Matteo <br>
<o:p></o:p></span></p>
<p>----------------------------------<o:p></o:p></p>
<p>The aim of this list is to facilitate the discussion between users of the
FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and
EEG analysis.<o:p></o:p></p>
<p>http://listserv.surfnet.nl/archives/fieldtrip.html<o:p></o:p></p>
<p>http://www.ru.nl/fcdonders/fieldtrip/<o:p></o:p></p>
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<p>----------------------------------</p>
<p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> http://listserv.surfnet.nl/archives/fieldtrip.html</p>
<p> http://www.ru.nl/fcdonders/fieldtrip/</p>