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Thanks a lot, Haiteng, but that was not really the issue. I have a
specific interval I'm interested in and by using dpss over that
interval, my frequency resolution is better than if I use TFRs and
then average.<br>
<br>
The problem really was in my cfg for the stats and I've just found
out what it was. Don't know why (stupid me!!), but I set cfg.tail =
1 and that of course will only give me the right tail
(posclusters!!)<br>
<br>
Thanks anyways, Vitória<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 4/13/2014 11:08 PM, Haiteng Jiang
wrote:<br>
</div>
<blockquote
cite="mid:CAHSK_TSE9ezdYrnOnC=-jJ=r8tx2VAYp-6tf5JTiW=tY=gH+nQ@mail.gmail.com"
type="cite">
<div dir="ltr">Hi Viotira,<br>
<div> If you don't care about time information , you can
average it by specifying cfg.avgovertime = 'yes' on the TFR ,
then the cluster will be formed in channel-frequency format.
If you use mtmfft , you should pre-select effect interval .
Otherwise, it could be not consistent .</div>
<div>
Best,</div>
<div>
Haiteng</div>
<div> </div>
<div> </div>
<div> </div>
<div> <br>
<div class="gmail_extra"><br>
<br>
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0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<br>
Message: 1<br>
Date: Sun, 13 Apr 2014 18:53:10 -0700<br>
From: Vit?ria Piai <<a moz-do-not-send="true"
href="mailto:v.piai.research@gmail.com">v.piai.research@gmail.com</a>><br>
To: FieldTrip discussion list <<a
moz-do-not-send="true"
href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br>
Subject: [FieldTrip] freqstatistics with sbj_chan_freq<br>
Message-ID: <<a moz-do-not-send="true"
href="mailto:534B3F86.9070904@gmail.com">534B3F86.9070904@gmail.com</a>><br>
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Format="flowed"<br>
<br>
Hi all,<br>
<br>
I'm kinda stuck not being able to figure out what's
going wrong with my<br>
freqstats, so I thought I could share it here and see if
anyone can see<br>
where I'm going wrong.<br>
When I run freqstatistics on TFRs, I get a negative
cluster (p = .001)<br>
between 8 and 25 Hz with the topography very similar to
the one in the<br>
figure. But I just want non-time-resolved spectra.<br>
So I have power spectra calculated with mtmfft (dpss
tapers) between 1<br>
and 50 Hz (5 Hz smoothing) and this is the one for which
I've been<br>
trying to run freqstatistics, unsuccessfully.<br>
I'm using a pretty standard cfg for freqstats
(basically, the same I use<br>
for the TFRs, which give me the negative cluster with p
=.001) and the<br>
data in the comparison are structured as sbj_chan_freq.
With this<br>
time-unresolved data, only posclusters are detected,
with ps > .4! If I<br>
plot the stat output, it has the exact same negative
cluster as I get<br>
for the TFRs (see Figure), and as far as I can see, no
real positive<br>
cluster, but the function doesn't even detect any
negative clusters.<br>
I must be doing something wrong because the
time-resolved and<br>
-unresolved effects are pretty much the same in the
descriptives. I<br>
remember running stats on time-unresolved data before
and getting a<br>
reasonable output, so I guess my ft_freqstatistics isn't
working well<br>
right now. I just can't figure out why.<br>
Does anyone have any tips for how I could go about to
find out why the<br>
negative clusters are being disregarded?<br>
<br>
Thanks a lot, Vit?ria<br>
</blockquote>
</div>
-- <br>
<div>
<div><font face="arial, helvetica, sans-serif">Haiteng
Jiang</font></div>
<div><font face="arial, helvetica, sans-serif">PhD
candidate</font></div>
<div><font face="arial, helvetica, sans-serif">Neuronal
Oscillations Group</font></div>
<div><font face="arial, helvetica, sans-serif">Donders
Institute for Brain, Cognition and Behaviour</font></div>
<div><font face="arial, helvetica, sans-serif">Centre for
Cognitive Neuroimaging</font></div>
<div><font face="arial, helvetica, sans-serif">Radboud
University Nijmegen</font></div>
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