Before revision: Stochastic differential equation (SDE) models have been extensively used for the description of processes with uncertainties arising in the queueing theory and behavioral sciences . A large class of the problems from these domains is characterized by the necessity to deal with several distinct groups of populations, which are usually labeled as "active" and "passive".
After revision: Stochastic differential equation (SDE) models have been extensively used for the description of processes with uncertainties arising in the operations research, behavioral sciences, and many other application areas . A large class of the problems from these domains is characterized by the necessity to deal with several distinct groups of populations, which are usually labeled as "active" and "passive".