The mean vector length modulation index (MVL-MI-Canolty) approach estimates PAC from a signal with length N, by combining phase (ϕ) and amplitude information to create a complex-valued signal: faei(ϕfp) (Canolty et al., 2006), in which each vector corresponds to a certain time-point (n). If the resulting probability distribution function is non-uniform, this suggests a coupling between fp and fa, which can be quantified by taking the length of the average vector.
