[Mne_analysis] Grand Averaging from Text Events Files

[Brian Coffman]

Hi Hari,
No, the normal averaging is doing the same thing. Just tested this.


On Wed, Jan 25, 2012 at 11:33 AM, Hari Bharadwaj
<hari at nmr.mgh.harvard.edu>wrote:

> Hi Brian,
>   Is the normal averaging (as opposed to grand averaging) working as
> expected for the individual runs with the behavioral corrected event
> files?
>
> Regards,
> Hari
>
>
> On Wed, January 25, 2012 12:37 pm, Brian Coffman wrote:
> > Hello MNE users,
> > I am having an odd issue that I am having trouble conceptualizing.
> >
> > I am averaging data that is split into 3 raw data files, then taking the
> > events files generated from these averages and modifying these events
> > files
> > to include only events where the subject responded correctly. I am then
> > taking these corrected events files and grand averaging the raw data to
> > end
> > up with a single .fif average which is corrected for our behavioral data.
> >
> > The issue I am having is related ot the initial offsets in the events
> > files. In all cases, there is an initial offset greater than zero for the
> > 2nd and 3rd raw data files. In some cases, there is also an initial
> offset
> > of a few seconds in the events file for the first of the three raw data
> > files. It seems from the log files that the offset is being utilized
> > differently for the two cases (a few seconds offset vs a whole dataset
> > offset). For the log from the first file, the offset is added to the
> > times,
> > while for the other files, the offset is not added. For example, with an
> > initial offset of 4 seconds, the log for the uncorrected average starts
> at
> > 29.555 seconds, while for the corrected data, the log starts at 33.555
> > seconds. The logs are identical for the second and third data files. This
> > is also apparent in the averages, as there is no signal in the corrected
> > average of the first raw file. It seems that the offsets are necessary
> for
> > the later files (data files 2 and 3), however, as I get no averages
> > without
> > them.
> >
> > My question is: Should I eliminate these offsets from the first text
> > events
> > file when averaging from events files? Is there something I have not
> > considered here?
> >
> >
> > Thanks in advance!!
> >
> > -Brian Coffman, M.S.
> > Research Associate, The Mind Research Network
> > Doctoral Candidate, The University of New Mexico
> >
> > Phone: (505) 336-0606
> > Fax: (505) 272-7011
> >
> > "I used to think that the brain was the most wonderful organ in my body.
> > Then I realized who was telling me this."
> >   - Emo Phillips
> > _______________________________________________
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> > Mne_analysis at nmr.mgh.harvard.edu
> > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis
>
>
> --
> Hari Bharadwaj
>
>
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-- 
-Brian Coffman, M.S.
Research Associate, The Mind Research Network
Doctoral Candidate, The University of New Mexico

Phone: (505) 336-0606
Fax: (505) 272-7011

"I used to think that the brain was the most wonderful organ in my body.
Then I realized who was telling me this."
  - Emo Phillips
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