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<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Hi Allen,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Thank you very much for the fast
response. So if I understand correctly, for a cluster map with X clusters
the largest cluster is compared to a permutation distribution created from the
largest ClusterStat of each permutation, the 2<sup>nd</sup> largest cluster to
a distribution constructed from the 2<sup>nd</sup> ClusterStat of each,
etc. If this is correct and the largest cluster is just being tested
using Max(ClusterStat), why do you say that this vector-based approach has less
power for the largest cluster? <span style='color:#1F497D'><o:p></o:p></span></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>You need a vector-valued critical value that controls the false
alarm rate for all cluster sizes jointly. The first element of this
vector-valued critical value is always larger than the critical value for a
scalar test statistic.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US> Also, the permutation distribution
for the smaller clusters may not have all 1000 values if some permutations have
fewer clusters, right? I appreciate the advice.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Right, but that does not create any problems.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>I’m curious to find out if the cluster-based permutation
tests reveal an interesting pattern in your data.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Best,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Eric<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Best,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Allen <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:Consolas'>__________________________________________________________________________________</span><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Allen Ardestani Email: <a
href="mailto:aardesta@ucla.edu">aardesta@ucla.edu</a><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Phone: (310) 825-5528<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Medical Scientist Training Program<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>David Geffen School of Medicine at UCLA<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Semel Institute for Neuroscience and Human
Behavior<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>760 Westwood Plaza<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Los Angeles, CA 90095-1759<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>USA<o:p></o:p></span></p>
</div>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> FieldTrip discussion list
[mailto:FIELDTRIP@NIC.SURFNET.NL] <b>On Behalf Of </b>Eric Maris<br>
<b>Sent:</b> Thursday, July 01, 2010 2:55 PM<br>
<b>To:</b> FIELDTRIP@NIC.SURFNET.NL<br>
<b>Subject:</b> Re: [FIELDTRIP] Vector-valued ClusterStats<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Verdana","sans-serif";color:#1F497D'>Hi
Allen,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Verdana","sans-serif";color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Verdana","sans-serif";color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>I’ve already looked at the 2007 JMN
paper by Maris and Oostenveld, but still have some remaining questions about
using a vector-valued test statistic to assess differences between 2 conditions
(correct vs incorrect memory task performance). I’ve attached a
cluster map showing the many different sizes and shapes that make it necessary
to use a vector-valued test statistic.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>The different sizes and shapes of the clusters does not force
one to use a vector-valued test statistic.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>1)<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>Do the existing FT functions
handle vector-valued stats?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Vector-valued stats are not supported by the
ft_timelockstatistics and ft_freqstatistics functions (which call
statistics_montecarlo). They are supported by the older function
clusterrandanalysis, but I’m not sure how this function will behave give
that Fieldtrip has gone through several changes.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Don’t expect too much of a vector-valued test statistic.
For detecting the largest cluster, the vector-valued test statistic has LESS
power than the scalar test statistic (Max(clusterstat)). I have played around
with the vector-valued test statistic but there were few cases where it made a
difference.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>2)<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>Are all ClusterStats from each
permutation (bigger than a minimum size) included when constructing a
multivariate permutation distribution?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Yes.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>3)<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>Are clusters of all sizes
compared to the same permutation distribution? I.e., would the 3<sup>rd</sup>
largest cluster be compared to a permutation distribution obtained from just
the 3<sup>rd</sup> largest stat from each permutation?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>The answer to your specific question is “yes”.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo2'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>4)<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>Our trials each have a baseline
period – in order to assess the differences between the two conditions,
should we limit the permutation distribution to stats selected just from the
active periods of each permutation?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>You can compare to a baseline that has the same number of
samples as a data segment obtained in some experimental condition.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Best,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'>Eric Maris<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Verdana","sans-serif";color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-GB style='font-family:"Verdana","sans-serif";
color:#1F497D'>dr. Eric Maris<br>
Donders Institute for Brain, Cognition and Behavior<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-GB style='font-family:"Verdana","sans-serif";
color:#1F497D'>Center for Cognition and F.C. Donders Center for Cognitive
Neuroimaging<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-GB style='font-family:"Verdana","sans-serif";
color:#1F497D'>Radboud University</span><span lang=EN-US style='font-family:
"Verdana","sans-serif";color:#1F497D'><br>
</span><span lang=EN-GB style='font-family:"Verdana","sans-serif";color:#1F497D'>P.O.
Box 9104</span><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><br>
</span><span lang=EN-GB style='font-family:"Verdana","sans-serif";color:#1F497D'>6500
HE Nijmegen<br>
The Netherlands<br>
T:+31 24 3612651<br>
Mobile: 06 39584581<o:p></o:p></span></p>
<p class=MsoNormal><span lang=DE style='font-family:"Verdana","sans-serif";
color:#1F497D'>F:+31 24 3616066<br>
E: e.</span><span style='font-family:"Verdana","sans-serif";color:#1F497D'><a
href="mailto:e.maris@donders.ru.nl" title="blocked::mailto:maris@nici.kun.nl"><span
lang=DE>maris@donders.ru.nl</span></a></span><span lang=EN-US style='font-family:
"Verdana","sans-serif";color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-family:"Verdana","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Thank you very much in advance!<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:10.5pt;font-family:Consolas'>__________________________________________________________________________________</span><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Allen Ardestani Email: <a
href="mailto:aardesta@ucla.edu">aardesta@ucla.edu</a><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Phone: (310) 825-5528<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Medical Scientist Training Program<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>David Geffen School of Medicine at UCLA<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Semel Institute for Neuroscience and Human
Behavior<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>760 Westwood Plaza<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Los Angeles, CA 90095-1759<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>USA<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><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>
<p><span lang=EN-US>----------------------------------<o:p></o:p></span></p>
<p><span lang=EN-US>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></span></p>
<p><span lang=EN-US>http://listserv.surfnet.nl/archives/fieldtrip.html<o:p></o:p></span></p>
<p><span lang=EN-US>http://www.ru.nl/fcdonders/fieldtrip/<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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</body>
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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>