[Eeglablist] extracting Epochs

[Malte Anders]

Lina,

When you run ASR and have "Remove bad data periods instead of correcting
them" checked, the algorithm probably removed 24 of your triggers as the
algorithm declared them as "bad". When you later extract the epochs, the
triggers were removed with the result that you end up with fewer epochs
than expected.

You have some options here:
-Increase the asr parameter (e.g. from 20 to 40) and see with how many
epochs you end up with
-uncheck "remove bad data points instead of correcting them"
-skip asr for now, analyze your data without artifact correction, apply ASR
in a second run and see if your results have increased, maybe even after
costing you some epochs.

Best,
Malte


Lina Ismail <linaelsherif at knights.ucf.edu> schrieb am Fr., 8. Mai 2020,
11:58:

> Dear all,
> I am following Makotos  preprocessing order (02/28/2020 updated)
> as follows:
>
>   1.  Change the option to use double precision
>   2.  Import data
>   3.  Downsample if necessary
>   4.  High-pass filter the data at 1-Hz (for ICA, ASR, and CleanLine)
>   5.  Import channel info
>   6.  Remove line noise using CleanLine
>   7.  Apply clean_rawdata() only to reject bad channels.
>   8.  Interpolate all the removed channels
>   9.  Re-reference the data to average
>   10. Apply clean_rawdata() only to perform Artifact Subspace
> Reconstruction (ASR).
>   11. Re-reference the data to average again--this is to reset the data to
> be zero-sum across channels again.
>   12. Run AMICA using calculated data rank with 'pcakeep' option (or
> runica() using 'pca' option)
>   13. Estimate single equivalent current dipoles
>   14. Search for and estimate symmetrically constrained bilateral dipoles
>
> My question  is after step 11 which means before running AMICA,  I starts
> extracting the data epochs it gave me few number of epochs compared to my
> real epochs. for example, 9 but I suppose to have 33. However, when I skip
> doing Artifact Subspace Reconstruction (ASR) alone byt remove the bad
> channels it gave me the correct number of epochs!
> Do you have clarification for that?
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
>