<html><head><base href="x-msg://411/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Aleksandra,<div><br></div><div>there is a check box in the STUDY menu that allows you to subtract the average power from each individual. Does that solve your problem?</div><div>Thanks,</div><div><br></div><div>Arno</div><div><br><div><div>On 11 Oct 2012, at 23:39, Aleksandra Vuckovic wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-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; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div ocsi="x"><div style="font-family: Tahoma; direction: ltr; color: rgb(0, 0, 0); font-size: x-small; "><div>Dear Arno,</div><div><font face="tahoma">that is what I've expected but how can one then compare powers between two group ( looking at a peak frequency of e.g. two groups of patients) being sure that the difference does not come from individual difference in EEG amplitude?</font></div><div><font face="tahoma">Or other way around, how can we replace a value of the absolute power in a STUDY with the relative power and then visualise it using the<a></a><span class="Apple-converted-space"> </span>STUDY tools?</font></div><div><font face="tahoma">Many thanks,</font></div><div><font face="tahoma">Aleksandra</font></div><div dir="ltr"><font color="#000000" size="2" face="Tahoma"></font> </div><div id="divRpF169434" style="direction: ltr; "><hr tabindex="-1"><font color="#000000" size="2" face="Tahoma"><b>From:</b><span class="Apple-converted-space"> </span>Arnaud Delorme [<a href="mailto:arno@ucsd.edu">arno@ucsd.edu</a>]<br><b>Sent:</b><span class="Apple-converted-space"> </span>12 October 2012 02:28<br><b>To:</b><span class="Apple-converted-space"> </span>Aleksandra Vuckovic<br><b>Cc:</b><span class="Apple-converted-space"> </span><a href="mailto:tarikbelbahar@gmail.com">tarikbelbahar@gmail.com</a>; M Abul Hassan;<span class="Apple-converted-space"> </span><a href="mailto:eeglablist@sccn.ucsd.edu">eeglablist@sccn.ucsd.edu</a><br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [Eeglablist] Is power calculated in STUDY and in dataset is abs or relative?<br></font><br></div><div></div><div>Dear Aleksandra,<div><br></div><div>power is absolute when plotting the spectrum and relative to baseline when computing ERSP as Tarik mentioned.</div><div>Best,</div><div><br></div><div>Arno</div><div><br><div><div>On 9 Oct 2012, at 01:48, Aleksandra Vuckovic wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span"><div><div style="font-family: Tahoma; direction: ltr; color: rgb(0, 0, 0); font-size: x-small; "><div>Hi,</div><div><font face="tahoma">what Abul<a></a><a></a> Hasan<a></a><a></a><span class="Apple-converted-space"> </span>is asking is whether the Power calculated in EEGLab<a></a><a></a><span class="Apple-converted-space"> </span>in certain frequency<a></a> band<a></a><span class="Apple-converted-space"> </span>is absolute or relative (e.g. for example is it Power (8-12 Hz) or Power (8-12 Hz)/Power(1-40 Hz) )</font></div><div><font face="tahoma">This is a relevant question if one wants to compare mean Power values between two groups in a STUDY. We need to be sure that the difference is not coming from the fact that people in one group have a higher amplitude EEG but that their relative power in certain frequency band is higher as compare to the other group.</font></div><div><font face="tahoma">Can anybody give us a clue how to get a relative power using STUDY so we can use all nice graphical presentation and statistics?</font></div><div><font face="tahoma"></font> </div><div><font face="tahoma">Many thanks,</font></div><div><font face="tahoma">Aleksandra</font></div><div><font face="tahoma"></font> </div><div id="divRpF323380" style="direction: ltr; "><hr tabindex="-1"><font color="#000000" size="2" face="Tahoma"><b>From:</b><span class="Apple-converted-space"> </span><a href="mailto:eeglablist-bounces@sccn.ucsd.edu">eeglablist-bounces@sccn.ucsd.edu</a><span class="Apple-converted-space"> </span>[<a href="mailto:eeglablist-bounces@sccn.ucsd.edu">eeglablist-bounces@sccn.ucsd.edu</a>] On Behalf Of Tarik S Bel-Bahar [<a href="mailto:tarikbelbahar@gmail.com">tarikbelbahar@gmail.com</a>]<br><b>Sent:</b><span class="Apple-converted-space"> </span>08 October 2012 22:41<br><b>To:</b><span class="Apple-converted-space"> </span>M Abul Hassan<br><b>Cc:</b><span class="Apple-converted-space"> </span><a href="mailto:eeglablist@sccn.ucsd.edu">eeglablist@sccn.ucsd.edu</a><br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [Eeglablist] Is power calculated in STUDY and in dataset is abs or relative?<br></font><br></div><div></div><div>Greetings Abdul,<div><br></div><div>I am not an expert on the mechanics here,</div><div>but I believe if you are referring to ERSP computation using the newtimef function,</div><div>then the baseline of values before the 0 time point in your epochs is automatically subtracted.</div><div>Please also see multiple messages on this topic in recent months in the eeglablist archives.</div><div><br></div><div>Respectfully,</div><div>Tarik</div><div><br></div><div><br></div><div><br><br><br><div class="gmail_quote">On Fri, Oct 5, 2012 at 2:37 AM, M Abul Hassan<span class="Apple-converted-space"> </span><span dir="ltr"><<a href="mailto:abulhassan85@yahoo.com">abulhassan85@yahoo.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br><blockquote class="gmail_quote" style="border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0.8ex; padding-left: 1ex; "><table border="0" cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><div>Dear all</div><div> </div><div>I want to know the power spectrum generated by EEGLAB both in a STUDY and in each dataset seperately is using absolute values or relative values.</div><div> </div><div>If it based on relative values than how a frequency range can be known?</div><div> </div><div>If it is based on absolute values than how can I calculate the relative power in EEGLAB?</div><div> </div><div>Thanks</div><div>Best Regards</div><div>Muhammad Abul Hasan</div></td></tr></tbody></table><br>_______________________________________________<br>Eeglablist page:<span class="Apple-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="Apple-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="Apple-converted-space"> </span><a href="mailto:eeglablist-request@sccn.ucsd.edu">eeglablist-request@sccn.ucsd.edu</a><br></blockquote></div><br></div></div></div>_______________________________________________<br>Eeglablist page:<span class="Apple-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="Apple-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="Apple-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></span><br class="Apple-interchange-newline"></blockquote></div><br></div></body></html>