Frederica -<div><br class="webkit-block-placeholder"></div><div> You've misinterpreted -- ICA learns a (channels,channels) unmixing matrix, so the number of data frames (time points) needed to separate as many components increases as the square of the number of channels. The faq is a bit out of date -- in our work with 72-256 channel data in the lab, we have found that as the channel density becomes high, good ICA solutions typically require a considerable multiple of the channel number squared (up to 30 or more for 256-channel data). </div>
<div><br class="webkit-block-placeholder"></div><div>For 148-channel data I would like to collect 30*128^2 ~ 650k (~40 min of data at 256 Hz) ... though it could well be that smaller data sets could also give useful solutions. I will update the faq to better reflect this, and will try to do a numerical study to get a more detailed heuristic understanding.</div>
<div><br class="webkit-block-placeholder"></div><div>Scott Makeig<br><br><div class="gmail_quote">On Feb 16, 2008 2:36 AM, Federica Di Grazia <<a href="mailto:federicadigrazia@hotmail.com">federicadigrazia@hotmail.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<div><font face="Calibri"></font> </div>
<div style="font:10pt arial">----- Original Message -----
<div style="background:#e4e4e4"><b>From:</b> <a title="federicadigrazia@hotmail.com" href="mailto:federicadigrazia@hotmail.com" target="_blank">Federica Di Grazia</a> </div>
<div><b>To:</b> <a title="eeglablist@sccn.ucsd.edu" href="mailto:eeglablist@sccn.ucsd.edu" target="_blank">eeglablist@sccn.ucsd.edu</a> </div>
<div><b>Sent:</b> Tuesday, January 29, 2008 10:13 PM</div>
<div><b>Subject:</b> question on SICA approach</div></div>
<div><br></div>
<div><font face="Calibri">I saw the faq on Independent Component
Analysis but I couldn't understand how many samples(in time) I need
to analyze 148 channels with SICA approach?</font></div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri">I saw that it's necessary a number of samples(in time)
equal to the square of the channels, but for SICA </font> <font face="Calibri">the sample are represented by the 148 channels, so I need the
square root of 148 as samples(in time)</font><font face="Calibri">?</font></div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri">Best Regards,</font></div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri">____________________________________________________________________</font></div>
<div> </div>
<div><font face="Calibri">Federica Di Grazia<br>Ph. D. Student in Electronics,
Automation and Complex Systems Engineering<br>Dipartimento di Ingegneria
Elettrica Elettronica e dei Sistemi<br>Università degli Studi di Catania<br>v.le
A.Doria 6 - 95125 Catania, Italy<br>Tel. +39-095-7382342<br>Fax
+39-095-330793<br>e-mail: <a href="mailto:fdigra@diees.ing.unict.it" target="_blank">fdigra@diees.ing.unict.it</a><br>
<a href="mailto:federicadigrazia@hotmail.com" target="_blank">federicadigrazia@hotmail.com</a>
<br>____________________________________________________________________</font></div></div>
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