[Eeglablist] How much data is necessary for ICA?

[Makoto Miyakoshi]

Dear Dana and John,

Since higher frequency ranges in scalp-recorded EEG data does not have much
power (due to 1/f PSD) nor information, I recommend you use the 'rule of
thumb' that John showed with additional assumption that your sampling rate
is around 250 Hz so that up to 250/2 Hz data are taken into account as
significant data part.

If you apply this change to the formula, the answer is updated as follows

128^2*30/256/60 = 32 minutes minimum

This is a soft limit as the factor 30 could be 20 according to several
papers by Onton and Makeig. If you use 20, then it'll be around 20 min.

Makoto

On Fri, May 8, 2020 at 7:52 AM John Johnson <john.johnson at gatech.edu> wrote:

> Hi Dana,
>
> The rule of thumb is:
> (channels^2)*30 as found
> [here](https://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline)
> so
> 128^2*30/1024/60 = 8 minutes minimum
>
> Regards,
> John
>
> John T. Johnson
> PhD Candidate - Cognitive Motor Control Laboratory
> Lab TA NEURO 4001 Neuroscience Capstone
> School of Biological Sciences
> Georgia Institute of Technology
> john.johnson at gatech.edu
> he/him/his
>
> On 26 Apr 2020, at 11:01, Son, D.M.E. van wrote:
>
> > Dear EEGLab list members,
> >
> > I have a question related to ocular and artifact rejection with ICA to
> > obtain ERPs. I read ICA might not be ideal if there are not enough
> > data points (e.g. if you only have a short EEG recording per subject).
> > There seem to be ways to cope with this, such as reducing the number
> > of channels, having a higher sample rate or using PCA.
> >
> > We will have 20 minutes of data per subject, 128 channels and recorded
> > the data with 1024 p/s. Does anyone know whether this will be enough
> > to confidently apply the ICA? Is reducing the number of channels or an
> > extra PCA before ICA recommended?
> >
> > Many thanks in advance
> >
> > Dana
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