“…In a theoretical treatment the coupling strength is clearly the scaling parameter of the coupling functions. There is great interest in being able to evaluate the coupling strength for which many effective methods have been designed (Mormann et al, 2000;Rosenblum and Pikovsky, 2001;Paluš and Stefanovska, 2003;Marwan et al, 2007;Bahraminasab et al, 2008;Staniek and Lehnertz, 2008;Chicharro and Andrzejak, 2009;Smirnov and Bezruchko, 2009;Jamšek, Paluš, and Stefanovska, 2010;Faes, Nollo, and Porta, 2011;Sun, Taylor, and Bollt, 2015). The dominant direction of influence, i.e., the direction of the stronger coupling, corresponds to the directionality of the interactions.…”