System Dynamics Applications / 2 / 2.8

2.8 IMPORTANCE OF STRUCTURE—MODELS AND REAL-WORLD PROBLEMS

It has been stressed several times that a fundamental principle in system dynamics modelling is that the structure of a problem is a key determinant of dynamic behaviour. Alternatively stated, a model of a systemic problem will exhibit dynamic behaviour because of its structure. The concept of structure is frequently taken for granted, seemingly without detailed understanding of what is meant.

In any problem situation, information exists at various levels of aggregation and typically in hierarchies. There can be feedback loops both within and between levels in hierarchies. These links between levels and component parts of these hierarchies contribute to the emergent properties of systems (Checkland, 1981). Further, there is communication between levels and between component parts. This communication takes the form of policies and governing business rules which also contribute to the behaviour of systemic problems.

In this book we examine systemic structure in detail and explain how the relevant component parts fit together to form structures and how dynamic behaviour is produced as a consequence.

A few visionaries in the system dynamics modelling field have cleverly exploited the notion of structure in various activities such as model building, policy analysis and strategy development. Once the building blocks of structure have been identified their interrelationships can be investigated. This is essential to developing insights into dynamic behaviour and its causes.