[Mne_analysis] Applying Inverse to Evoked vs Applying Inverse to Epochs and Averaging

[Rockhill, Alexander P.]

Hi Alex,

    Thank you that makes sense and was along the lines of what I expected.

    I assume then that doing the former (applying the inverse to evoked data) is best practice over doing the later (applying inverse epochs and averaging). Is that your understanding as well?

Thanks,

Alex
________________________________________
From: mne_analysis-bounces at nmr.mgh.harvard.edu [mne_analysis-bounces at nmr.mgh.harvard.edu] on behalf of Alexandre Gramfort [alexandre.gramfort at inria.fr]
Sent: Friday, November 03, 2017 12:28 PM
To: Discussion and support forum for the users of MNE Software
Subject: Re: [Mne_analysis] Applying Inverse to Evoked vs Applying Inverse to Epochs and Averaging

when you apply inverse operator to epochs you have more noise which
corresponds to the nave attribute in evoked (nave == number of
averaged epochs), which is 1 for single epochs.

also you have the SNR.

the consequence is that the regularization parameter is slightly
different when you apply the inverse to epochs or to evoked.

HTH
Alex



On Fri, Nov 3, 2017 at 4:11 PM, Rockhill, Alexander P.
<AROCKHILL at mgh.harvard.edu> wrote:
> Hi all,
>
>     I tried applying an inverse model to the evoked data and also applying
> inverse epochs directly to the same epochs that were averaged to make the
> evoked data and then averaging the data from the list of source space time
> courses, and these matrices weren't the same. Does anyone have any insight
> as to why this would be?
>
> Thanks,
>
> Alex
>
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