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<span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">Dear Fieldtrippers,</span><br>
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In <a href="http://www.fieldtriptoolbox.org/reference/ft_artifact_muscle" id="LPNoLP225724">ft_artifact_muscle</a>, an EEG signal is first filtered - usually with a bandpass filter with cutoff frequencies of [110,140]. The documentation then says that the hilbert
envelope is calculated, after which the envelope values are z-transformed before they are thresholded.</div>
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However, is this sound? Whereas the actual filtered EEG values (the result of the bandpass filter) are usually normally distributed, the hilbert envelope values are far from. </div>
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What is the rationale for calculating the z-transform of a non-Gaussian distribution? Doesn't that introduce problems?</div>
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Best,</div>
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Kris</div>
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