[Eeglablist] Can I apply cluster weights to all EEG data?

[Mikołaj Magnuski]

Hi Rachel,

If by getting "weights for the cluster" you mean getting average ic weights
for the cluster components - this is a bad idea. The ic weight maps can be
diverse across  components within a cluster (even if estimated dipole
positions are similar) and averaging across these is not meaningful (no
subject has an average component; to keep the ic signal relevant you need
to use ic weights obtained at the individual level).

I also recommend measure projection - you can google:
eeglab measure projection toolbox

You will find egglab page describing the toolbox. See also the paper that
is referenced there that introduces measure projection - the description of
the method is very clear.
27 cze 2014 02:18 "Cooper, Rachel" <rcoopea at essex.ac.uk> napisał(a):

> Hi all,
>
> This is partly a theoretical question and partly a practical one. I have a
> study with 2 participant groups and 3 repeated measures factors. So far I
> have run ICA on my epoched data and then used cluster analysis. My problem
> is that the clusters which are most interesting (i.e., they look like
> relevant ERPs and contain the most ICs) contain lots of ICs from some
> participants and none from others. I assume this must be the case in any
> study with a between subjects factor.
>
> A suggestion from my PhD supervisor was to find the weights for the
> cluster and then apply these weights to the EEG data for every participant
> and every condition. That way I can compare these new component activations
> across my conditions/subjects knowing that the same IC component is being
> compared. Is it safe to do this theoretically?
>
> On a practical level, I have found the data used to plot the cluster scalp
> map in STUDY.cluster(clust).topo. However, I don't know how I would use
> this to apply cluster weights to the rest of my data as it is not a matrix
> of channels x ICs like the regular ICA weights. Is there another way to
> access the weights for a cluster?
>
> Any help is much appreciated and if you need more detail please let me know
> This is a fantastic list!
>
> Rachel
>
> Rachel Cooper
> PhD researcher
> Department of Psychology,
> University of Essex,
> Wivenhoe Park,
> Colchester,
> Essex,
> CO4 3SQ
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