<html>
<head>
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Hello Tarik,<br>
<br>
thank you very much for your comments on PCA and ICA. It was all
very helpful!<br>
<br>
I would agree that the ICA results are easier to interpret and
more vaild without a previous reduction of the dimensionality of
the data with PCA. For now, I decided to go ahead without the PCA.<br>
<br>
When I get the chance I might compare both methods and see for
myself. I think the advantage of doing a PCA first is that there
are fewer ICs to look at. In my experience most components beyond
30 (when sorted with respect to variance explained) don't look
like physiologically plausible brain activity, so it's always a
pain to look through all of them. But apart from that, I don't
think there is a good reason to apply PCA in our case.<br>
<br>
Regards, <br>
Martin<br>
<br>
<br>
On 12.01.2013 01:24, Tarik S Bel-Bahar wrote:<br>
</div>
<blockquote
cite="mid:CABCAK+gacyim+KWLUzTRmdgYqpZ0Q3YTjacv08iwGMJxhTMDDQ@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="MS Exchange Server version
08.03.0279.000">
<title>Re: [Eeglablist] Reduction of Data Dimensionality before
ICA</title>
<!-- Converted from text/plain format -->
<p><font size="2">Greetings Martin,<br>
<br>
just a one small clarification point:<br>
I meant that not doing PCA should allow you to retain the true<br>
dimensionality of your dense EEG data,<br>
and doing ICA to this non-reduced data should lead to an ICA<br>
decomposition that more accurately<br>
reflects the true dynamics within your eeg data. Cheers!<br>
</font>
</p>
</blockquote>
<br>
</body>
</html>