## Agent-Based (AB) compared with System Dynamics (SD) Simulations

"System dynamics, which is connected to the work of Forrester (1961), grounds modelling on difference equations and impinges upon the assumption that the behaviour of individuals that are embedded within a social system can be explained by the feedback nature of causal relationships that characterises the structure of the system.Agent-Based models, on the other hand, simulate actions and interactions of autonomous individual entities and build on the hypothesis that the behaviour of social systems can be modelled and understood as evolving out of interacting but autonomous learning agents (Epstein and Axtell 1996; Axelrod 1997; Axtell 1999). Thus, a crucial feature of agent-based models is the emergence of ordered structures independently of top-down planning.

While Agent-Based models show how the interaction among individual decision-making and learning may generate complex aggregate behaviour, the SD approach aims at reducing emerging aggregate, and often puzzling, behaviours into underlying feedback causal structures. As a consequence, SD models typically aggregate agents into a relatively small number of states assuming their perfect mixing and homogeneity (Rahmandad and Sterman 2008). On the other hand, ABM preserves heterogeneity and individual attributes at the risk of relinquishing robustness and parsimony." --

-- Edoardo Mollona,

"Computer simulation in social sciences,"

J Manage Gov(2008) 12:205-211.Some papers that compare the two:

- Hans J. (Jochen) Scholl, AB and SD Modeling : A Call for Cross Study and Joint Research,
System Sciences, 2001. Proc. of the 34th Annual Hawaii Int. Conf. on System Sciences, 2001,Here.

- Hans J. (Jochen) Scholl, Looking Across the Fence: Comparing Findings From SD Modeling Efforts With those of Other Modeling Techniques,
Proc. of the 19th Int. Conf. of the SD Society, 2001,Here.

- Nadine Schieritz and Andreas Größler, Emergent Structures in Supply Chains -- A Study Integrating AB and SD Modeling,
Proc. of the 36th Hawaii Int. Conf. on System Sciences - 2003, Here.

- Nadine Schieritz and Peter M. Milling, Modeling the Forest or Modeling the Trees. Comparison of SD and AB Simulation ,
Proc. of the 21st Int. Conf. of the SD Society, 2003Here.

- Wayne W. Wakeland, Edward J. Gallaher, Louis M. Macovsky, C. Athena Aktipis, A Comparison of SD and AB Simulation Applied to the Study of Cellular Receptor Dynamics,
Proc. of the 37th Hawaii Int. Conf. on System Sciences - 2004Here.

- A Borshchev, A Filippov, From SD and Discrete Event to Practical AB Modeling: Reasons, Techniques, Tools,
Proc. of the 22nd Int. SD Conf., 2004Here

- Nadine Schieritz, Exploring the Agent Vocabulary -- Emergence and Evolution in SD,
Proc. of the 22nd Int. SD Conf., 2004Here.

- An AB NetLogo version (by Owen Densmore) of Sterman's famous SD Beer Game, Here.

- H. Rahmandad and J. Sterman, Heterogeneity and Network Structure in the Dynamics of Diffusion: Comparing Agent-Based and Differential Equation Models,
Management Science, vol 54, no. 5, 2008. Here.

- Edoardo Mollona, Computer simulation in social sciences,
J Manage Gov(2008) 12:205-211. Here.

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Last Updated 11 August, 2010Robert Marks, bobm@agsm.edu.au