[Eeglablist] How rejection small parts of epoch affects time-frequency analysis?

[Sean Gilmore]

I am currently preprocessing my data using ICA to prep the data for time-frequency analysis. My stimuli was administered for ~54 seconds and so I am defining each epoch as [1 54] seconds after each trigger. I intend to examine the time-frequency information contained across these epochs, specifically examining the power of the frequency spectrum. 

I have been reading about conducting two ICA in order to obtain clean ICs. To do this I have seen some people sub-dividing their epochs into  smaller epochs as to prevent the rejection of large amounts of data when rejecting artifactual epochs. I would like to implement this pipeline as it seems like a good way to clean the data without having to discard large amounts of data.

My concern is with rejecting smaller sections of the larger epochs and how this will effect time-frequency decompositions. For example, If I ran a FFT on a epoch which had smaller sections removed (due to the presence of artifacts) would this effect the legitimacy of the results? Likewise, how would this effect my ability to obtain phase values from the epoch? 

Please let me know. 


Cheers
-
Sean Gilmore, M.A. candidate
Department of Psychology
Ryerson University







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