Directed information · TE(X→Y) · bivariate coupling detection
Transfer entropy TE(X→Y) = Σ p(y_{t+1},y_t,x_t) log[p(y_{t+1}|y_t,x_t)/p(y_{t+1}|y_t)] measures directional information flow from X to Y beyond Y's own history. Granger causality tests whether X's past helps predict Y's future. Both detect asymmetric coupling in coupled stochastic systems. Here X and Y are coupled AR(1) processes.