[Eeglablist] Change reference after ICA

[Delorme, Arnaud]

Dear Haneen,

If you want to compare with the literature, it is always better to use the same reference as what was used in a given article. Change of reference will potentially change the shape (latency/amplitude) of ERPs.

Also, when you reference your data, ICA components will be re-referenced as well, so you do not need to re-run ICA after changing your reference. This assumes that all data channels (including reference(s)) are included in the ICA decomposition. For example, if you do not include linked ears in the ICA decomposition, you cannot re-reference the data to linked ears and assume ICA components will be properly referenced (the function will return an error).

Best wishes,

Arno

> On Mar 5, 2020, at 10:53 AM, Joseph Dien <jdien07 at mac.com> wrote:
> 
> Although there are different preferences, there’s nothing intrinsically wrong with using CAR during analysis and yes you can always rereference.
> 
> You may find these papers helpful:
> 
> Dien, J. (1998). Issues in the application of the average reference: Review, critiques, and recommendations. Behavior Research Methods, Instruments, and Computers, 30(1), 34–43.
> Dien, J. (2017). Best practices for repeated measures ANOVAs of ERP data: Reference, regional channels, and robust ANOVAs. Int J Psychophysiol, 111(1), 42–56. https://doi.org/10.1016/j.ijpsycho.2016.09.006 <https://doi.org/10.1016/j.ijpsycho.2016.09.006>
> 
> Joe
> 
>> On Feb 25, 2020, at 23:46, Haneen Alsuradi <haneen at nyu.edu> wrote:
>> 
>> Hi,
>> 
>> I had online reference of Fcz channel and I changed it to CAR during
>> preprocessing. After changing reference to CAR, I performed ICA and removed
>> blinks and muscle artifacts. I wish to perform ERP analysis. I am wondering
>> is it ok to perform ERP analysis while having signals CAR referenced? I
>> read some articles that recommend using T7 or T8 as references in case of
>> ERP analysis. If so, can I re-reference at this point?
>> 
>> Will appreciate your feedback and insight!
>> 
>> Best
>> Haneen
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> 
> --------------------------------------------------------------------------------
> 
> Joseph Dien, PhD
> Senior Research Scientist
> Department of Human Development and Quantitative Methodology
> University of Maryland, College Park
> http://joedien.com
> 
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