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3 Types of Simulation 27

– Organizations, which we here define as structures of persons related to each other
in order to purposefully accomplishing work or some other kind of activity. That
is, the persons of an organization share some of their goals. Further details on the
modelling and simulation of organizations are provided in (Dignum 2013).
– Economic systems, which are organized structures in which actors (individuals,
groups, or enterprises) are trading goods or services on a market. Chapter 25
(Rouchier 2017) takes a closer look at markets.
2. Natural systems, such as:
– Animal societies, which consist of a number of interacting animals, such as an ant
colony or a colony of birds. Chapter 24 (Hemelrijk 2017) is devoted to simulation
of animal societies.
– Ecological systems, in which animals and/or plants are living and evolving in a
relationship to each other and in dependence of the environment (even if humans
also are part of the ecological system, they are often not part of these simulation
models). In Chap. 22 (Le Page et al. 2017) more details on the simulation of
ecological systems are discussed.
3. Socio-technical systems, which are hybrid systems consisting of both living
entities (in most cases humans) and technical artefacts interacting with each
other. Examples of this type of system are transportation and traffic systems
concerning the movement of people or goods in a transportation infrastructure
such as a road network. Chapter 26 (Ramstedt et al. 2017) provides a review of
simulation studies in these areas.
4. Artificial societies, which consist of a set of software and/or hardware entities, i.e.
computer programmes and/or robots, with individual goals. One type of artificial
societies, namely, distributed computer systems, is treated in Chap. 23 (Hales
2017).
In addition, there are systems that are interesting to simulate using a micro-
level approach but that we do not regard as social systems and are therefore not
treated in this book. One class of such systems are physiological systems, which
consist of functional organs integrated and co-operating in a living organism, e.g.
subsystems of the human body. Physical systems, which are collections of passive
entities following only physical laws, constitute another type of nonsocial systems.

3.4 Modelling

Let us now focus on how to model the system to be simulated. This depends on
the type of system and the purpose of the simulation study. An individual- or
agent-based model of a system consists of a set of entities and an environment
in which the entities are situated. The entities are either individuals (agents) that
have some decision-making capabilities or objects (resources) that have no agency
and are purely physical. There are a number of characteristics that can be used to