ABM intro talk

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QUT Digital Media Research Centrehttp://www.qut.edu.au/research/dmrc

Patrik Wikstrm | 26 June 2015Agent-based modelling and simulation

Patrik Wikstrm | QUT DMRC | 2015Many phenomena in comm & media studies can be conceptualised as complex adaptive systems (CAS)Large number of (locally) interacting elements.Any element is affected by and affects several other elements.The interactions are non-linear: small changes in can cause large effects.

CAS are dynamic and have a history. They evolve and their past is co-responsible for their present behaviour.It may be difficult or impossible to define system boundaries.CAS operate under far from equilibrium conditions.

Emergence: micro level actions generate macro level patterns.(Micro motives & macro behaviour)

(e.g. Miller & Page 2007)

Patrik Wikstrm | QUT DMRC | 2015

It is challenging to build a theory that is able to capture such complexities

Patrik Wikstrm | QUT DMRC | 2015The paper with the largest circulation in a market has financial and economic advantages that enable it to increase advertising and circulation sales by attracting customers from the smaller paper. As the leading paper attracts more circulation, it attracts more advertising, which in turn attracts more circulation, trapping the secondary paper in a circulation spiral that ultimately leads to its demise.Traditional modelling approaches are simply not very useful:Verbal models


Signifiersound imageSignifiedconceptTraditional modelling approaches are simply not very useful:Verbal models


Traditional modelling approaches are simply not very useful:Statistical (e.g. regression) models


Interactions between feral cats, foxes, native carnivores, and rabbits in Australia.System of differential equationsTraditional modelling approaches are simply not very useful:Mathematical models

Patrik Wikstrm | QUT DMRC | 2015Computational modelling, however, seems like a promising approach (1)In a computational model, concepts, assumptions, logic, and propositions are represented by a computer program.The model allows you to simulate the passing of time and observe how constructs that are included in the model change over time. This enables the researcher to analyse complex dynamic processes that non-computational modelling approaches are unable to capture.

Patrik Wikstrm | QUT DMRC | 2015Computational modelling, however, seems like a promising approach (2)The simulations generate data that can be validated against real-world data. If the model is able to replicate real-world processes, it is reasonable to argue that the assumptions, propositions and logic that are underpinning the computational model is a plausible explanation of the observed real-world processes. The validated model can then be used to make structured experiments and generate what-if scenarios in order to make contributions to theory.

Patrik Wikstrm | QUT DMRC | 2015There are different types of computational modelling; one is Agent-Based Modelling (ABM)

Patrik Wikstrm | QUT DMRC | 2015Computational models vs other modelsFewer assumptions, potentially easier to validateNon-linearityNon-equilibriumTimeCorrelational vs logical relationships

Patrik Wikstrm | QUT DMRC | 2015Agent-based simulation models are able to capture the peculiarities of CAS fairly wellHeterogeneous entities (agents) interact with the environment and with other agents.Agents have perception, a set of behaviours, memory & cognition, and follow certain rules or policies.Agents interact in a space that can be a representation of a physical space, but doesnt have to be.Agents can be modelled as nodes in a network.Simple rules on micro (agent) level generate complex patterns on macro (population) level.Feedback between micro and macro scales.(Emergence & immergence)


NOLA White: blue dots; African American: green dots; Asian: red; Latino: orange; all others: brown

Agent-based simulation modelling is still in its infancy in our field but is increasingly accepted in social sciences such as economics, sociology, pol sci and anthropology.


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The process for simulation supported theory development is fairly conventionaltheory as process; that is, theory as an ever-developing entity, not as a perfected product (Glaser & Strauss, 1999 [1967]: 32)

Model developmentBuild a computational model that takes as its input a set of constructs, propositions, logic, assumptions about locally interaction agents.Data collection & analysisModel validation and simulation experimentsIf the model is able to replicate macro-level behaviour that can be observed in the real world then we might argue that the theory behind the model is a plausible explanation to the observed behaviour.

Patrik Wikstrm | QUT DMRC | 2015Useful links

Download NetLogo:http://ccl.northwestern.edu/netlogo/5.2.0/

NetLogo models discussed during the workshop:https://github.com/qut-dmrc/simple-models

This presentation:http://www.slideshare.net/patrik/abm-intro-talk

Useful papers/theses/etc.:https://paperpile.com/shared/ypQIj8


ABM intro talk

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Transcript of ABM intro talk