[FieldTrip] WPLI question
martinvinck at gmail.com
Wed Jun 1 12:07:17 CEST 2011
As it is computed in ft_connectivity_wpli it preserves the information about the sign, i.e. whether the average imaginary component of the cross-spectrum is positive or negative.
That is, it estimates the average imaginary component of the cross-spectrum divided by the average magnitude of this imaginary component.
By taking the absolute value over the output one gets a measure of the strength of the interaction,- WPLI as it is defined in the paper, by taking the sign one gets a measure of the direction of the interaction.
The debiased WPLI estimator gets negative however as a consequence of the debiasing method - different issue.
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