[Eeglablist] Applying ICA weigthing matrix from one set to another

[Sarah Hosni]

Hello,
   
  I read previous messages on : "Applying ICA weigthing matrix from one set to another"
  and I saw two replies: one saying that "Yes, this is correct since the data was recorded on the same day. The best approach though is to concatenate all datasets and run ICA (as ICA is more stable with more data)."
  the other reply was:"your procedure is methodolologically uncorrect. The results of the ICA, the components and the weight matrix, are always differents if you change datasets, because all the dataset are different, and the ICA works whith this data."
   
  I want to ask: if I'll concatenate all datasets and run ICA .. this will make ICA an offline method, meaning I have to run it on all data first. and if it's wrong to use same weight matrix for different sets.. then I can't see how ica can be really useful in removing EOG artifacts.
   
  In my experiments, I trained ICA on one 10 second trial for each subject and then used the resulting weight matrix to remove EOG from other trials for the same subject recorded in different sessions. and it worked.. SO my question is: was what I did wrong?
  I was thinking that the eye independent component for each subjects will remain the same.
   
  another question: if I obtained my weight matrix from training on a 10 second EEG segment, can I use it to remove EOG from a smaller segment say an 0.5 second window of the same 10 second EEG instead of applying it on the whole data ( as ICA is more stable with more data but actually when we need to remove EOG is from small contaminated windows)

  thank you


 
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