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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi all - I have a question about epoch consistency when using the STUDY feature. I've seen 6 other posts on this but haven't seen a resolution. Can anyone help?
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<div>I have collected continuous data throughout an experimental session. I wrote software to display stimuli, capture performance data, and send marker from software to EEG data stream.</div>
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<div>The experiment structure has 8 30 second blocks per subject (120 blocks total). (this is exploratory so subject N is low.) I used EEGLAB epoch to extract the 30 sec from each block based on unique marker for a particular block. So, for each subject,
I have 15 30 sec blocks of continuous data. All are 3840 frames (30 x 128 sampling).</div>
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<div>I have tried several different iterations of setting up a STUDY but all say that epoch consistency is no. I double checked allpnts etc as noted by Arno in another post and these parameters check out. A couple of questions:</div>
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<div>Since I have continuous data only (no repeated epochs), does EEGLAB not recognize the data as an epoch and so determine epoch consistency = no based on that? If so, would putting a copy of the 30 block data in the same file allow STUDY to see <span style="font-size: 13.3333px;">determine
epoch consistency = yes.</span></div>
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<div><span style="font-size: 13.3333px;">Also, while the data seem to be pretty clean overall, there are some segments identified for rejection. However, if I reject the data, the epochs will be of different lengths and then would EEGLAB </span><span style="font-size: 13.3333px;">determine
epoch consistency = no because of unequal epoch length? Sort of a catch 22.</span></div>
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<div><span style="font-size: 13.3333px;">I know that EEGLAB is designed with ERP in mind but I'm trying to figure out how to best use it for analyzing continuous data.</span></div>
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<div><span style="font-size: 13.3333px;">Thanks for any and all advice.</span></div>
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<div><span style="font-size: 13.3333px;">Rich<br>
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<div id="divRpF946958" style="direction: ltr;"><font face="Tahoma" size="2" color="#000000"><b>From:</b> eeglablist-bounces@sccn.ucsd.edu [eeglablist-bounces@sccn.ucsd.edu] on behalf of Makoto Miyakoshi [mmiyakoshi@ucsd.edu]<br>
<b>Sent:</b> Friday, March 18, 2016 3:32 AM<br>
<b>To:</b> Whitehead, Kimberley<br>
<b>Cc:</b> eeglablist@sccn.ucsd.edu<br>
<b>Subject:</b> Re: [Eeglablist] epochconsist treats files with only one epoch as a continuous file<br>
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<div dir="ltr">Dear Kim,
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<div>Thank you for your suggestion. If you wish, would you please share your finding in EEGLAB Bugzilla as enhancement? </div>
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<div><a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__sccn.ucsd.edu_bugzilla_enter-5Fbug.cgi&d=BQMFaQ&c=eLbWYnpnzycBCgmb7vCI4uqNEB9RSjOdn_5nBEmmeq0&r=MNemh5cDBpfHugrLsdnWIQ&m=DLYGVpCNw1x2U8nCpCfUyVtrj3scQCzX3-d_6I8-r6w&s=SsINElwl-XLHZ0hl21YqnZj8gw0PVvHYbo6mVlsqkJ4&e=" target="_blank">https://sccn.ucsd.edu/bugzilla/enter_bug.cgi</a><br>
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<div>By the way I've encountered a similar situation. I learned that one cannot make a single epoch with EEGLAB. Unfortunately I forgot how I work around the issue (probably I repeated the epoch twice so that it is recognized as a one-time repeated two epochs?)</div>
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<div>Makoto</div>
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<div class="gmail_quote">On Wed, Jan 20, 2016 at 4:46 PM, Whitehead, Kimberley <span dir="ltr">
<<a href="mailto:k.whitehead@ucl.ac.uk" target="_blank">k.whitehead@ucl.ac.uk</a>></span> wrote:<br>
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<p class="MsoNormal">Hello<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I wonder if anybody could please offer some advice on altering the eeg_checkset code so that it doesn’t automatically treat files with one epoch as continuous. I think the issue is here:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">In eeg_checkset line 182:<u></u><u></u></p>
<p class="MsoNormal">case 'epochconsist', % test epoch consistency<u></u><u></u></p>
<p class="MsoNormal"> % ----------------------<u></u><u></u></p>
<p class="MsoNormal"> res = 'no';<u></u><u></u></p>
<p class="MsoNormal"> datasettype = unique_bc( [ EEG.trials ] );<u></u><u></u></p>
<p class="MsoNormal"> if datasettype(1) == 1 & length(datasettype) == 1, return; %<u></u><u></u></p>
<p class="MsoNormal">continuous data<u></u><u></u></p>
<p class="MsoNormal"> elseif datasettype(1) == 1, return; %<u></u><u></u></p>
<p class="MsoNormal">continuous and epoch data<u></u><u></u></p>
<p class="MsoNormal"> end;<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">The code says that if there is only 1 epoch, the file is continuous. This means<u></u><u></u></p>
<p class="MsoNormal">that if I try to include this file in a study in which most files have several<u></u><u></u></p>
<p class="MsoNormal">epochs, it says there is no epoch consistency and there is an error when I try<u></u><u></u></p>
<p class="MsoNormal">to do FFT analysis. However, the nature of my analysis means there are many<u></u><u></u></p>
<p class="MsoNormal">files with only 1 epoch. (My epochs are spontaneous transients in EEG which<u></u><u></u></p>
<p class="MsoNormal">I've zeropadded to make the same duration/same number of data points. I've<u></u><u></u></p>
<p class="MsoNormal">split them up by topography so it's common that in 1 file there may be just one<u></u><u></u></p>
<p class="MsoNormal">with, for example, a right occipital topography.)<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks, Kim<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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-- <br>
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<div dir="ltr">Makoto Miyakoshi<br>
Swartz Center for Computational Neuroscience<br>
Institute for Neural Computation, University of California San Diego<br>
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