Hi Steve, <br><br>Thanks for your replay.<br><br>I meant the average in that dead channel. When scrolling data before baseline correction I was not able to display the signal in that channel unless using a very large scale (above 2000) when of course all lines were flat . However after baseline correction it displayed signal similar to the rest of the channels. This channel also showed a flat line in the Biosemi actiview software when recording.<br>
<br>greets<br>Gorka<br><br><br><div class="gmail_quote">On 24 October 2012 04:28, Stephen Politzer-Ahles <span dir="ltr"><<a href="mailto:politzerahless@gmail.com" target="_blank">politzerahless@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Gorka,<br><br>Do you mean you found a normal ERP average in other channels? That would not be surprising, because baseline-correcting one channel doesn't affect other channels. On the other hand, if you mean that the channel had no data before baseline correction but then suddenly had a normal ERP after baseline correction, then I'm not sure why that would happen either...<br>
<br>Best,<br>Steve Politzer-Ahles<br><br><div class="gmail_quote"><div><div class="h5">On Tue, Oct 23, 2012 at 9:47 AM, Gorka Fraga Gonzalez <span dir="ltr"><<a href="mailto:gorkafraga@gmail.com" target="_blank">gorkafraga@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<p class="MsoNormal"><span lang="NL">Dear EEGlab
experts,</span></p>
<p class="MsoNormal"><span lang="NL"> </span></p>
<p class="MsoNormal">I am analyzing data collected with a Biosemi 64 channels
system. After a large sample tested one electrode did not get any signal in the last
subjects so it was manually checked and apparently is dead.</p><p class="MsoNormal"><br></p><p class="MsoNormal"> However after preprocessing data without excluding this channel I found a normal ERP average. The data was
analysed in EEglab as it follows: </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> Import ref average of mastoids// bandpass
filter (1-70)// downsample to 256hz// Epoched// Remove baseline (…)</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I found that it was only after the “remove baseline “step
that I could see signal in that channel when manually scrolling the data. </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">It would be great if any of you could give me an explanation
on this, since after reading about what the “baseline removal” procedure
does it is still not clear to me why this could happen</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Many thanks in advance </p><span><font color="#888888">
<p class="MsoNormal">Gorka</p>
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</font></span></blockquote></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><br>-- <br>Stephen Politzer-Ahles<br>
University of Kansas<br>Linguistics Department<br><a href="http://people.ku.edu/~sjpa/" target="_blank">http://people.ku.edu/~sjpa/</a><br>
</font></span></blockquote></div><br>