Although you can find a number of various definitions of Agent Based Modeling in the literature, from the viewpoint of practical applications agent based modeling can be defined simply as essentially decentralized, individual-centric (as opposed to system level) approach to model design. When designing an agent based model the modeler identifies the active agents, the agents (which can be people, companies, projects, assets, vehicles, cities, animals, ships, products, etc.), defines their behavior (main drivers, reactions, history, ...), puts them in a certain environment, maybe establishes connections, and runs the simulation. The global (system-level) behavior then emerges as a result of interactions of many individual behaviors. AnyLogic supports Agent Based modeling (as well as Discrete Event and System Dynamics Modeling) and allows you to efficiently combine it with other approaches.
The traditional modeling approaches are treating the company’s
employees, projects, products, customers, partners, etc. either as
aggregated averaged quantities or as passive agents/resources in a
process. For example, the system dynamics models are full of
assumptions like “we have 120 employees in R&D, they can
design about 20 new products a year”, or “we have a fleet
of 1200 trucks, they can move that much cargo in a month, and 5% of
them need to be replaced each year”. In process-centric (also
known as discrete event) approach you would view your organization as a
number of processes, such as: “a customer calls a call center, it
is first handled by operator of type A, which takes on average 2
minutes, then 20% of the calls need to be forwarded to…”.
Those approaches are indeed more capable than “spreadsheet-based
modeling”, they can capture organization dynamics, non-linearity,
but they ignore the fact that all those people, products, projects,
pieces of equipment, assets, etc are all different, have their
histories, intentions, desires, individual properties, and also complex
relationships. For example, people may have different expectations
regarding their income and career, can have significantly different
productivity in different teams, R&D projects interact and
and may depend one on another, aircrafts have their individual and
rigid maintenance schedules, whose combination may lead to fleet
availability problems, a customer may consult his family members before
making the purchase decision, etc. Agent based approach is free of such
limitations as it suggests that the modeler directly focuses on
individual objects in and around the organization, their individual
behaviors, and their communication. The agent based model is actually a
set of interacting agents that reflect objects and
relationships in the real world, and thus is a natural step forward in
understanding and managing the complexity of today’s business and
These days companies and governmental organizations have
tons of useful data in their CRM, ERP, HR databases that are very much
underutilized. Agent based modeling is a natural way to leverage that
data and make them work. As long as agent based models are essentially
individual-based, they can be populated with agents whose properties
are real and read directly from e.g. a CRM system (in case we are
modeling the market), or from ERP/HR database in case we are modeling
the dynamics of the human resources inside the organization. This gives
you easy, very precise and always up to date way to model,
forecast, compare scenarios and optimize strategy.
A good example application for ABM is consumer market. In the
dynamic, competitive and complex market environments (telecom,
insurance, leasing, health, etc) the consumer’s choice
essentially depends on a number of individual characteristics, inherent
dynamics of the consumer, network of contacts, external influences that
may be best captured within the agent based modeling paradigm,
especially taken the high availability of individual-centric data from
the CRM (Customer Relationships Management) systems that can be
directly used to parameterize the agents.
Another traditional example would be epidemiology. Here agents are people that can be susceptible, infectious, recovered, immune to the disease, etc. ABM allows to explicitly capture social networks, contacts between people, their heterogeneity, and therefore to obtain better forecasts of the disease spread.
You however should not think of ABM as of analysis method applicable only to large people communities. There are problems in manufacturing, logistics, supply chains, or business processes where ABM works better than anything else. For example, the behavior of a complex machine that has internal states, inherent timing, different reactions in different modes, etc. may be efficiently modeled by a separate object (agent) with a statechart inside that may be linked to the manufacturing process workflow. The supply chain participants (companies – producers, wholesalers, retailers) have their own goals and rules and can naturally be represented as agents. Agents can even be projects or products within one company have internal states and dynamics, compete for company resources.
Before deciding to use the agent based approach you should investigate the problem and verify whether traditional approaches can be used. For example, if the system you are modeling fits well with the process flow paradigm (i.e. can be described as a sequence of operations on essentially passive agents) it may be beneficial to use AnyLogic Process Modeling Library objects instead of specifying individual behaviors of those agents. Similarly, if the agents in your system have no individuality (no individual history, timing, etc.) it may be worth applying System Dynamics approach.
Agent based models used in practice are very diverse, and it would be virtually impossible to develop a universal "Agent Based Library" and reduce the modeler's work to a number of drag-and-drop operations. There are however some reusable "design patterns" that simplify development of agent based models and are directly supported by AnyLogic. These patterns are in:
From architectural viewpoint, a typical AnyLogic agent based model would have at least two agent types: Main type for a top-level object where agents would be contained and another type of agent, e.g. Person. A number of agents would be embedded into the Main object, e.g. as a population people of type Person. Main will act as an environment, here you can specify properties shared by the agents. You are free however to define other hierarchies in your agent based model, for example you may have companies-agents that contain employees-agents and communicate with consumers-agents.
Here are some useful facts aimed to ensure you are not misguided by academic literature and various "theories" of agent based modeling: