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3 Types of Simulation 25

In this chapter, we will describe the main purposes of computer simulation and
also give an overview of the main issues that should be regarded when developing
computer simulations.

3.2 Purposes of Simulation

We can identify a number of distinct purposes of simulation. In general terms,
simulation is almost always used for analysing (some aspects of) a system, typically
by predicting future states. More specifically, we may say that in the case when the
user is observing the simulation, the purpose is often one of the following:
– Management of a system, where simulation of (parts of) this system is used to
support operational decisions, i.e. which action to take, or strategic decisions, i.e.
which policy to use. The chapters on application areas in this book provide some
examples of this purpose; e.g. Chap. 22 addresses environmental management
(Le Page et al. 2017).
– Design or engineering of a system, where simulation is used as a tool to support
design decisions when developing a system. Chapter 23 illustrates how simu-
lation can help in the design of distributed computer systems (Hales 2017). In
fact, many new technical systems are distributed and involve complex interaction
between humans and machines, which makes individual-based simulation a
suitable approach. The idea is to model the behaviour of the human users, which
is useful in situations where it is too expensive, difficult, inconvenient, tiresome,
or even impossible for real human users to test out a new technical system. An
example of this is the simulation of “intelligent buildings” where software agents
model the behaviour of the people in the building (Davidsson 2000).
– Evaluation and verification, where simulation is used to evaluate a particular
theory, model, hypothesis, or system, or compare two or more of these. Moreover,
simulation can be used to verify whether a theory, model, hypothesis, system, or
software is correct. An example of this purpose is found in Chap. 4 of this book
(Edmonds et al. 2017). More generally, in the context of social theory building,
simulations can be seen as an experimental method or as theories in themselves
(Sawyer 2003). In the former case, simulations are run, e.g. to test the predictions
of theories, whereas in the latter case, the simulations themselves are formal
models of theories. Formalizing the ambiguous, natural language-based theories
of the social sciences helps to find inconsistencies and other problems and thus
contributes to theory building.
– Understanding, where simulation is used to gain deeper knowledge of a certain
domain. In such explorative studies, there is no specific theory, model, etc. to be
verified, but we want to study different phenomena (which may however lead to
theory refinement). Chapter 24 in this volume provides a number of examples
how simulation has helped in understanding animal social behaviour (Hemelrijk
2017).