<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'>Hey Raghavan,<br><br>You're welcome. A quick solution to set you in the right direction would be to point you to the respective documentation: http://www.sciencedirect.com/science/article/pii/S1053811912011597<br>I believe some, maybe most, of your points are addressed by that paper (saving some copy&pasting in here).<br><br>best,<br>Arjen <br><br><hr id="zwchr"><blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;padding-left:5px;"><b>Van: </b>"Raghavan Gopalakrishnan" <gopalar.ccf@gmail.com><br><b>Aan: </b>"fieldtrip" <fieldtrip@science.ru.nl><br><b>Verzonden: </b>Maandag 7 april 2014 18:59:33<br><b>Onderwerp: </b>[FieldTrip] regressconfound<br><br><div dir="ltr"><div>Arjen,</div><div><br></div><div>Thanks for all your previous help on using regressconfound.</div><div>It would be great if you can shed light on some questions I asked earlier (See below).</div><div>Also, when applying regressconfound to time-frequency (TF) data, regressconfound removes variance from TF from individual trials. So, utimately regressconfound helps to improve the induced TF responses rather than evoked responses. (By induced, I mean calculating TF on trial by trial basis and then computing average, But evoked I mean calculating TF on averaged data)</div>
<div>If one is interested in only evoked, then regressconfound would not be of much help. Is that correct?</div><div><br></div><div>Thanks,</div><div>Raghavan</div><div><br></div><div><br></div><div><br></div><div><br></div>
<div><br></div><br clear="all"><div><span style="font-family:arial,sans-serif;font-size:13px">Date: Wed, 26 Feb 2014 11:38:23 -0500</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">From: Raghavan Gopalakrishnan <</span><a href="mailto:gopalar.ccf@gmail.com" style="font-family:arial,sans-serif;font-size:13px" target="_blank">gopalar.ccf@gmail.com</a><span style="font-family:arial,sans-serif;font-size:13px">></span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">To: </span><a href="mailto:fieldtrip@science.ru.nl" style="font-family:arial,sans-serif;font-size:13px" target="_blank">fieldtrip@science.ru.nl</a><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">Subject: [FieldTrip] regressconfound and statistics</span><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Message-ID: <</span><a href="mailto:A36DB35E-1C8A-4C8A-A0F3-083B8E1131C1@gmail.com" style="font-family:arial,sans-serif;font-size:13px" target="_blank">A36DB35E-1C8A-4C8A-A0F3-083B8E1131C1@gmail.com</a><span style="font-family:arial,sans-serif;font-size:13px">></span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">Content-Type: text/plain; charset=windows-1252</span><br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px">
<span class="" style="background-color:rgb(255,255,204);font-family:arial,sans-serif;font-size:13px">Arjen</span><span style="font-family:arial,sans-serif;font-size:13px">,</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">I agree with your steps and your assumptions about my data, though I am only interested in evoked activity. I am indeed doing the steps 1 and 2 in the correct order. I just kept the 4 blocks and confounds associated with them separate from each other (for book keeping purposes), but I used the mean head position of all 4 blocks to demean the translations and rotations in each block. Technically, I guess this is the same as appending the blocks prior to running regress confound.</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">When I said, "However, the problem is, whatever significance I found earlier (i.e. by comparing means rather than t-statistic) doesn?t test significant now.? I was comparing the means of the data that has been run through regress confound. When I plot (sum square of all gradiometers in each subject in each condition) before and after regress confound, I see some differences. Should I not see any differences at all?</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px"> But there is one catch. What do I do if I am comparing a condition across different time points, rather than 2 conditions in one time point? MEG collected at two different time points will have different average head positions. In that case, should I use one average head position (computed from time point - 1) and use that to demean the translations and rotations in rest of the time points?</span><br style="font-family:arial,sans-serif;font-size:13px">
<br style="font-family:arial,sans-serif;font-size:13px"><br style="font-family:arial,sans-serif;font-size:13px"><span style="font-family:arial,sans-serif;font-size:13px">Thanks for your support.</span><br style="font-family:arial,sans-serif;font-size:13px">
<span style="font-family:arial,sans-serif;font-size:13px">Raghavan</span><br style="font-family:arial,sans-serif;font-size:13px"></div>-- <br><div dir="ltr"><br></div>
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<br>_______________________________________________<br>fieldtrip mailing list<br>fieldtrip@donders.ru.nl<br>http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</blockquote><br><br><br>-- <br><div><span name="x"></span>Donders Institute for Brain, Cognition and Behaviour<br>Centre for Cognitive Neuroimaging<br>Radboud University Nijmegen<br><br>Email: a.stolk@donders.ru.nl<br>Phone: +31(0)243 68294<br>Web: www.arjenstolk.nl<span name="x"></span><br></div></div></body></html>