[Eeglablist] preprocessing continuous data for spectral analysis with welch approach

[Agnieszka Zuberer]

hi everyone,

we would like to perform a spectral analysis for Theta, Alpha and Beta
power based on the welch approach on our continuous data sets, recorded
with 3 scalp electrodes (FZ, CZ, OZ) referenced to the mastoid.

We gained bad results with both regression based artifact corrections
(Gratton, 1983) and ICA. Reading the preprocessing tutorials of eeglab for
continuous datasets, we wonder about the order of following procedures

a) reject continuous portions of data based on spectrum (with pop_rejcont)
b) reject continuous portions by simple mv-threshold (iterating through the
raw data in 1 second-steps and reject portions exceeding 150mv)
c) perform pwelch spectral analysis

Our question is, what is worse:
- performing a pwelch approach on "cleaned" data resulting in breakes in
the data
*or *
- performing a pwelch approach on raw uncorrected data while maintaining
the continuity of the data and reject data afterwards with indices for
segments marked for rejection

thank you very much for helping us out.

Agnieszka
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