<html><head><base href="x-msg://1753/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Veerle,<div><br></div><div>you can run ICA twice in a row and use the first ICA to detect bad portion of data or bad channels (because it is often easier to detect these when looking at ICA components). After you have removed bad portion of data or bad channels, you may rerun ICA.</div><div><br></div><div>But you should not remove ICA components, then rerun ICA (the data dimension would be reduced and this will force ICA to run PCA first - assuming it is able to automatically detect the dimension reduction). In other words, do not do it.</div><div><br></div><div>Thanks,</div><div><br></div><div>Arno</div><div><br><div><div>On 19 Feb 2013, at 01:36, Veerle ROSS 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 lang="NL-BE" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Hi all<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">For a current study we are applying ICA. Because our lab was not free of noise we wanted to run ICA 2 times and we hope to obtain cleaner components the second time.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">After searching the internet and the literature we are still not sure what the limits of such a second ICA run are.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Therefore we were wondering:<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 36pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>1.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">Is it even possible to indicate ICA components in both the first and second ICA<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 72pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>a.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">We read that you can use the PCA option for this to reduce the dimensions<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 72pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>b.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">However why can’t we use ICA the second time?<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 72pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>c.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">Other sites mention that you shouldn’t indicate components in the first ICA<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 36pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>2.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">If we run ICA 2 times<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 72pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>a.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">Should we only remove the noise the first time?<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 72pt; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -18pt; "><span lang="EN-US"><span>b.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><span lang="EN-US">Or should we also already indicated components such as blinks, bad channels, etc.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Thanks in advance.<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US">Regards, Veerle Ross<o:p></o:p></span></div><div style="margin-top: 0cm; margin-right: 0cm; margin-left: 0cm; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span lang="EN-US"><o:p> </o:p></span></div></div>_______________________________________________<br>Eeglablist page:<span class="Apple-converted-space"> </span><a href="http://sccn.ucsd.edu/eeglab/eeglabmail.html" style="color: blue; 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