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Publication Modeling limits to growth(Springer, Cham, 2016-06-15) Duggan, JimThis chapter introduces system dynamics models of limits to growth. First, a one-stock model is presented, where the growth rate varies, and is influenced by the system’s carrying capacity. Second, a model of economic growth is described, which captures the law of diminishing returns, a feature of many economic systems. Third, a two-stock model of limits to growth is specified, where a growing stock consumes its carrying capacity, and this dynamic leads to growth followed by rapid decline. Before introducing the limits to growth models, an explanation of an important formulation method in system dynamics is presented. This allows modelers to construct robust equations to model the effect of one variable on another. This is useful for many system dynamics models, particularly where one system stock influences another system stock.Publication An introduction to system dynamics(Cham: Springer, 2016-06-15) Duggan, JimThis chapter presents the important concepts underlying the system dynamics modeling method. Following an initial definition of the term model, a summary of a successful system dynamics intervention is described. The key concepts of system dynamics stocks and flows are explained. The process for simulating stock and flow models integral calculus is described, with an example of a company s customer base used to illustrate how stocks change, through their flows, over time. A summary of dimensional analysis for stock and flow equations is provided before the second feature of system dynamics modeling feedback is presented. The chapter concludes by summarizing the system dynamics meth-odology, which is a five-stage iterative process that guides model design, devel-opment, test and policy design.