Meeting Critical Real-World Challenges In Modelling Complexity: What System Dynamics Modelling Might Learn From Systems Engineering

System dynamics is still evolving. This paper argues additional rigour is needed if system dynamics is to achieve its full potential in helping us understand complex behaviour of human activity systems. It argues that a detailed appreciation of how systems engineers define, analyse, specify, manufacture, operate and support complex systems could inform the evolution of system dynamics even though there are significant differences between the two disciplines. The proffered approach integrates systems thinking, system dynamics modelling and systems engineering. This integrated approach enables group model building and building of exceedingly complex models through top-down design and careful management of the complexity introduced at each stage of the model-building process. The approach promises to engender greater confidence that models developed using it work and are both necessary and sufficient representations of the real world. The greatest potential gain accruing from application of this methodology is enhanced acceptance of system dynamics. 1. SYSTEMS ENGINEERING AND SYSTEM DYNAMICS MODELLING In just over 40 years, system dynamics modelling has developed into a well-established body of knowledge. However, systems thinkers and system dynamics modellers are continually challenged to design and deliver highly effective strategies to remediate complex problems. How we go about building effective, verified and validated models of complex world behaviour tests our cognitive capacities to the limit. This paper suggests how we might exploit lessons and methodologies drawn from systems engineering practice to improve the effectiveness of system dynamics modelling, in particular by providing a framework within which we manage the complexity associated with modelling real-world behaviour. 1.1. A Common Interest in Understanding Complex Systems The inescapable similarity between systems engineering and system dynamics modelling is that they both exist to help us understand complex systems. In systems engineering we use this understanding to define, analyse, specify, manufacture, operate and support systems whilst in system dynamics modelling we set out to build models that assist us to manage within complex systems and to manage complex systemic problems. System dynamics modelling focuses on understanding complex systems and how they behave over time, using a single main technique of time-domain modelling and simulation supported by general systems theory and an appreciation of feedback structures.