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<p>Thanks Julian - I found the info I was looking for. Apologies - I should have checked the previous discussions first.</p>
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<p>Best wishes</p>
<p>Lizzie</p>
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<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">Lizzie Shephard, PhD</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">Postdoctoral researcher</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">2.21 MRC SGDP Centre</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">Institute of Psychiatry, Psychology, & Neuroscience</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">King’s College London</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">De Crespigny Park</span><span style="font-family:"Garamond","serif"; color:black"></span></p>
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<p class="MsoNormal" style="margin-bottom:0.0001pt"><span style="font-family:"Garamond","serif"; color:#1F497D">elizabeth.1.shephard@kcl.ac.uk</span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> fieldtrip-bounces@science.ru.nl <fieldtrip-bounces@science.ru.nl> on behalf of Julian Keil <julian.keil@gmail.com><br>
<b>Sent:</b> 17 February 2017 11:10<br>
<b>To:</b> FieldTrip discussion list<br>
<b>Subject:</b> Re: [FieldTrip] Negative values with debiased weighted phase lag index</font>
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<div>Dear Lizzie,
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<div>this comes up from time to time on the Mailinglist.</div>
<div>Check for example this response by Martin Vinck:</div>
<div><a href="https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmailman.science.ru.nl%2Fpipermail%2Ffieldtrip%2F2011-June%2F003892.html&data=01%7C01%7Celizabeth.1.shephard%40kcl.ac.uk%7Ccbe12a18f5fd4ba30c9c08d457264f41%7C8370cf1416f34c16b83c724071654356%7C0&sdata=uQ57ydU%2B3nFowiHUDFwvpV2usBijgVUOU8YPTJ%2FCkx8%3D&reserved=0">https://mailman.science.ru.nl/pipermail/fieldtrip/2011-June/003892.html</a></div>
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<div>Quote: <span class="Apple-style-span" style="font-family:monospace; white-space:pre">The debiased WPLI estimator gets negative however as a consequence of the debiasing method - different issue.</span>
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<div>Cheers,</div>
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<div>Julian</div>
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<div>Am 17.02.2017 um 12:05 schrieb Shephard, Elizabeth:</div>
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<div style="margin-top:0px; margin-bottom:0px">Dear all</div>
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<div style="margin-top:0px; margin-bottom:0px">I am using FieldTrip to explore connectivity in resting-state EEG data and aimed to use the debiased weighted phase lag index (dwPLI) to index this. However, I am finding a lot of negative values in my connectivity
matrices when I compute the dwPLI, and I am unsure why this might be - has anyone found this previously, or have an idea of why this might be happening? I do not get this if I compute other connectivity measures (e.g. coherence) and I have a decent amount
of clean trials (around 80 per subject) on which to run the connectivity. I am computing the dwPLI from fourier coefficients exported from a straightforward FFT. </div>
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<div style="margin-top:0px; margin-bottom:0px">Many thanks in advance for any advice</div>
<div style="margin-top:0px; margin-bottom:0px">Best wishes</div>
<div style="margin-top:0px; margin-bottom:0px">Lizzie</div>
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<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">Lizzie Shephard, PhD</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">Postdoctoral researcher</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">2.21 MRC SGDP Centre</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">Institute of Psychiatry, Psychology, & Neuroscience</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">King’s College London</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">De Crespigny Park</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">London, SE5 8AF</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)">0207 848 5272</span><span style="font-family:Garamond,serif; color:black"></span></div>
<div style="margin-top:0px; margin-bottom:0.0001pt"><span style="font-family:Garamond,serif; color:rgb(31,73,125)"><a href="mailto:elizabeth.1.shephard@kcl.ac.uk">elizabeth.1.shephard@kcl.ac.uk</a></span></div>
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