<html><head><base href="x-msg://39/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Lizzie,<div><br></div><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://mailman.science.ru.nl/pipermail/fieldtrip/2011-June/003892.html">https://mailman.science.ru.nl/pipermail/fieldtrip/2011-June/003892.html</a></div><div><br></div><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><div><br></div><div>Cheers,</div><div><br></div><div>Julian</div><div><br></div><div><div>Am 17.02.2017 um 12:05 schrieb Shephard, Elizabeth:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div id="divtagdefaultwrapper" dir="ltr" style="font-size: 12pt; color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; "><div style="margin-top: 0px; margin-bottom: 0px; ">Dear all</div><div style="margin-top: 0px; margin-bottom: 0px; "><br></div><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><div style="margin-top: 0px; margin-bottom: 0px; "><br></div><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><div style="margin-top: 0px; margin-bottom: 0px; "><br></div><div id="Signature"><div id="divtagdefaultwrapper" style="font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-family: Calibri, Arial, Helvetica, sans-serif; "><div name="divtagdefaultwrapper" style="font-family: Calibri, Arial, Helvetica, sans-serif; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255); margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><p class="MsoNormal" style="margin-top: 0px; margin-bottom: 0.0001pt; "><span id="ms-rterangepaste-start"></span></p><div style="margin-top: 0px; margin-bottom: 0.0001pt; "><span style="font-family: Garamond, serif; color: rgb(31, 73, 125); ">---------------------------------------------------------------------------</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); ">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><span id="ms-rterangepaste-end"></span><br><p style="margin-top: 0px; margin-bottom: 0px; "></p></div></div></div></div></div>_______________________________________________<br>fieldtrip mailing list<br><a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a><br><a href="https://mailman.science.ru.nl/mailman/listinfo/fieldtrip">https://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a></div></blockquote></div><br></div></body></html>