Before revision:  Here, we develop a method that classifies the source of global fluctuations of temporal networks according to these two mechanisms.We propose a dynamic hidden-variable model to formally define the two dynamical classes , with which we show that the global fluctuations in a real-world dynamical system can be explained by either of the two simple mechanisms.
After revision:  Here, we develop a method that classifies the source of global fluctuations of temporal networks . In doing so, we first show empirical evidence that real-world dynamical systems could be categorized into two classes, the difference of which is characterized by the way the number of edges grows with the number of active nodes, i.e., densification scaling. We develop a dynamic hidden-variable model to formally define the two dynamical classes , with which we show that the global fluctuations in a real-world dynamical system can be explained by either of the two simple mechanisms.