<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 12pt;
font-family:Calibri
}
--></style></head>
<body class='hmmessage'><div dir='ltr'>Thank you very much Arno. I understand this better now. So I believe that if I set the baseline from -1500 to 0, for example, the analysis may be taking values greater than 0 (after the stimulus) to calculate the baseline. In this case, t<span style="font-size: 12pt; ">he analyzed baseline would go from -1500 to 148? Should I then use -412ms as the minimum possible value for the baseline?</span><div><br></div><div>Also, unrelated to that, what is the purpose of the 'winsize' parameter? Is it the same as the moving window, meaning it would overwrite the 824ms?</div><div>Many thanks,</div><div>Ana<br><br><div>
<h4 align="left"><font face="Garamond, Times, Serif" color="#9933cc"></font> </h4><pre> </pre></div><br><br><div><div id="SkyDrivePlaceholder"></div><hr id="stopSpelling">Subject: Re: [Eeglablist] Edge artifacts with newtimef (problem with baseline)?<br>From: arno@ucsd.edu<br>Date: Thu, 28 Mar 2013 10:20:42 +0100<br>CC: eeglablist@sccn.ucsd.edu<br>To: sabato45@hotmail.com<br><br>Dear Ana,<div><br></div><div>at the lowest frequency, your moving window size is 824 ms, so if your epoch starts at -1500 ms, the center of the first window is located at -1088 ms. Because we only get spectral estimates at the center of windows, this is why you "loose" data on the edge. </div><div><br></div><div>And this is what we generally mean by "border" effect (although it can also be what Makoto was talking about). I have not heard of edge artifacts. However, you must remember that the window you use at the lowest frequency include a total of 824 ms of data although it is tapered (multiplied) by a gaussian (in the case of Morlet wavelets) to avoid window edge effects.</div><div><br></div><div>Best,</div><div><br></div><div>Arno</div><div><br><div><div>On 21 Mar 2013, at 00:11, Ana Navarro Cebrian wrote:</div><br class="ecxApple-interchange-newline"><blockquote><span class="ecxApple-style-span" style="border-collapse:separate;font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;orphans:2;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;font-size:medium;"><div class="ecxhmmessage" style="font-size:12pt;font-family:Calibri;"><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>_______________________________________________<br>Eeglablist page:<span class="ecxApple-converted-space"> </span><a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" target="_blank">http://sccn.ucsd.edu/eeglab/eeglabmail.html</a><br>To unsubscribe, send an empty email to<span class="ecxApple-converted-space"> </span><a href="mailto:eeglablist-unsubscribe@sccn.ucsd.edu">eeglablist-unsubscribe@sccn.ucsd.edu</a><br>For digest mode, send an email with the subject "set digest mime" to<span class="ecxApple-converted-space"> </span><a href="mailto:eeglablist-request@sccn.ucsd.edu">eeglablist-request@sccn.ucsd.edu</a></div></span></blockquote></div><br></div></div></div> </div></body>
</html>