<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">Hi Dave, a few thoughts below. If you come up with a good solution, thanks for sharing it with the list so that other users can learn from your experiences.<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">***********Notes for Dave<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*My understanding is that eeglab developers setup study to expect at least 2 or more trials per condition, but you may hear back from them with specifics. <br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*consider eliminating from your analyses the conditions were there are only a few or one epochs</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*note that comparing conditions that each have a different number of epochs is not considered a good thing in eeg research, wherein one needs to at least (statistically) control for the variable number of epochs one has across the different conditions. It's defendable if you have, say 129,135,152,142 epochs across 4 conditions; but if you're comparing, say 1,5,8,20 epochs across 4condition, that's problematic, at least due to noise/variability with low epoch counts and single epochs.<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*in eeg research world, it's usual to have 40+ epochs per condition, though for some well-established ERPs 15 epochs may be enough. This relates to the general idea that one needs to average across a number of epochs (aka trials) to get a clear/good event-related signal, and thus reduce the noise across the epochs. This depends to some degree on the phenomena under study, and the specific data collection protocol being used.<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*in your case, you may need to go outside of study and get EEG metrics (and average them up and run stats on them) from the individual single-subject files. Though I don't recommend it, doing so would at least allow you to get an estimate of your chosen EEG metrics for your one-epoch conditions (regardless of the validity issue with one or few epochs).<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*if you haven't had a chance to, consider reviewing methods and analyses in previous published eeg articles that are similar to your eeg study, and check out what their usual epoch counts are, and whether any analyze/include conditions where there are just one epoch. <br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*there is a burgeoning literature one can check out on single-trial metrics where one may find some useful techniques <br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff">*re wrangling with STUDY: One could try testing something out with the eeglab tutorial data (the tutorial data that has
multiple .set files with epochs in each file, which can be loaded up
into a study - and then delete all the epochs except one from one
single-subject file for one condition, and then see if study works -
this would be evidence that study can deal with single-subject files
that have one epoch)</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small;color:#0000ff"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jan 29, 2019 at 3:22 PM David Ryan <<a href="mailto:ryand1@goldmail.etsu.edu">ryand1@goldmail.etsu.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>Hello,<br></div><div><div class="gmail_quote"><div lang="EN-US"><div class="gmail-m_-3839793152186549894m_-2054598747510393865WordSection1"><p class="MsoNormal"><u></u></p>
<p class="MsoNormal">In my study I have several conditions (A, B,C…) and the epochs get organized into categories based on response (e.g., Condition A-Correct, Condition A-Incorrect, Condition B-Correct, Condition B-Incorrect, and so on…). This results with
several single response epochs for certain categories. When I load this into STUDY it says “Epoch Consistency = no” and leads to matrix dimension errors for the ERSP.
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">I have read through the Eeglablist and have found were several people want to analyze a single epoch as an epoch, not as continuous EEG - the EEGLAB default. The consistent response I have read is “ If there is one epoch, it cannot be recognized
as epoched”. My question is why? <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">How does a single epoch from a single subject in a condition with other multiple epochs from other subjects, all with the same epoch length not meet the criteria of epoch consistency? I know that EEGLAB reads a single epoch as continuous,
but is there no way to change/override this assumption?<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">In my own naïve attempt to address this issue, I tried to make single epochs “seem” the same in the STUDY structure by copying and formatting the ALLEEG.event information over to the ALLEEG.epoch. This still leaves the issue of the ALLEEG.trials
=1. <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Any more ideas to address this issue? <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks,<u></u><u></u></p>
<p class="MsoNormal">Dave<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">David Ryan, Ph.D.<u></u><u></u></p>
<p class="MsoNormal">Research Health Science Specialist <u></u><u></u></p>
<p class="MsoNormal">Hearing & Balance Research Program<u></u><u></u></p>
<p class="MsoNormal">James H. Quillen VAMC (621)<u></u><u></u></p>
<p class="MsoNormal">Research Service (151)<u></u><u></u></p>
<p class="MsoNormal">Mountain Home, TN 37684<u></u><u></u></p>
<p class="MsoNormal">(423)-926-1171 Ext. 7575<u></u><u></u></p>
<p class="MsoNormal"><img src="cid:16897d45043ad7999131" alt="HBRH" style="width: 267px; max-width: 100%;"><u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
</div>
</div></div>-- <br><div dir="ltr" class="gmail-m_-3839793152186549894gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><font size="3" face="Times New Roman" color="#000000">
</font><p style="margin:0in 0in 0pt"><a name="m_-3839793152186549894_SignatureSanitizer_SafeHtmlFilter__MailAutoSig"><span><font size="3" face="Calibri" color="#000000">David
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</font><p style="margin:0in 0in 0pt"><span><span><font size="3" face="Calibri" color="#000000">Research Health Specialist </font></span></span></p><font size="3" face="Times New Roman" color="#000000">
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</font><p style="margin:0in 0in 0pt"><span><span><font size="3" face="Calibri" color="#000000">Auditory Vestibular Research Enhancement Award Program (REAP)
</font></span></span></p><font size="3" face="Times New Roman" color="#000000">
</font><p style="margin:0in 0in 0pt"><span><span><font size="3" face="Calibri" color="#000000">Research Service</font></span></span></p><font size="3" face="Times New Roman" color="#000000">
</font><p style="margin:0in 0in 0pt"><span><span><font size="3" face="Calibri" color="#000000">(423)-926-1171 Ext. 7575</font></span></span></p><font size="3" face="Times New Roman" color="#000000">
</font><p style="margin:0in 0in 0pt"><a href="http://www.avreap.research.va.gov/" target="_blank"><span><span style="color:blue;font-size:12pt"><font face="Calibri">www.avreap.research.va.gov</font></span></span></a><span><span style="font-size:12pt"><font face="Calibri" color="#000000"> </font></span></span></p><font size="3" face="Times New Roman">
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