Dear Ana,<div><br></div><div>Suppose we use EEGLAB default dftfilt3() with 3 cycles 3 Hz for the lowest frequency. The sigma_t for this wavelet is 159 ms by dftfilt3(). Using this number, you can compute the radius of trust (Simonovski and Boltezar, 2003). This is k*159 ms, and you have to choose k from 3-6 (which suggests that there is no clear answer). Let's say we choose k = 5. Then about 800 ms out of 999 ms is consider to be practically unaffected by the edge effect. </div>
<div><br></div><div>Someone skilled in wavelet please read below and help me.</div><div><br></div><div>I also found e-folding time (Torrence and Compo, 1998) but could not understand 'scale' very well. How can I convert cycles, Hz, or FB into scale? According to them e-folding time is defined as sqrt(2)*scale. I found that 'cmor0.0506-3' is dftfilt3 equivalent at 3 Hz 3 cycle (but slightly different in scale... these inconsistencies causes headache). However, I was not able to figure out its scale.</div>
<div><br></div><div>Makoto</div><div><br><div class="gmail_quote">2013/3/20 Ana Navarro Cebrian <span dir="ltr"><<a href="mailto:sabato45@hotmail.com" target="_blank">sabato45@hotmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div dir="ltr"><span style="color:rgb(68,68,68);font-size:15px;line-height:21px">Dear eeglab users,</span><div style="line-height:21px;color:rgb(68,68,68);font-size:15px">I'm using newtimef to calculate the ERSP. My epochs are -1500 to 2000 ms long, and I'm using the time from -1500 to 0 as a baseline. </div>
<div style="line-height:21px;color:rgb(68,68,68);font-size:15px">I've been told that a baseline from -500 to -200 ms would be more optimal to avoid edge-artifacts, since my baseline starts at the same point that the beginning of my epoch (-1500ms). </div>
<div style="line-height:21px;color:rgb(68,68,68);font-size:15px"><br></div><div style="line-height:21px;color:rgb(68,68,68);font-size:15px">I don't observe any edge effects in my data (with the -1500 to 0 ms as a baseline), but I don't have other way to verify this and I'd like to make sure of it. Also, I believe that this is related to the fact that my ERSP plots only show from around -1088ms to 1586ms (instead of -1500 to 2000), but I would like to understand this better.</div>
<div style="line-height:21px;color:rgb(68,68,68);font-size:15px">Could anybody explain why I shouldn't worry about edge artifacts when using newtimef to calculate the ERSPs?</div><div style="line-height:21px;color:rgb(68,68,68);font-size:15px">
Many thanks,</div><div style="line-height:21px;color:rgb(68,68,68);font-size:15px">Ana<span style="font-size:12pt"> </span></div><pre> </pre> </div></div>
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-- <br>Makoto Miyakoshi<br>JSPS Postdoctral Fellow for Research Abroad<br>Swartz Center for Computational Neuroscience<br>Institute for Neural Computation, University of California San Diego<br>
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