Systems thinking and system dynamics: A primer

This chapter introduces the basics of the system dynamics simulation methodology, together with the adjunct field of systems thinking which emerged subsequently. It lists the various characteristics of system dynamics models. The stock-flow diagram in SD is the counterpart to the activity cycle diagram (ACD) in discrete-event simulation (DES). Although the flows may not result in a cycling of resources as such (which is common in DES), each diagram is there to underpin the formal model and the quantitative expressions which define its constituent elements. The chapter describes some important additional aspects of SD modeling such as use of soft variables, co-flows, exponential delays and model validation