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Social Simulation Tutorial. International Symposium on Grid Computing Taipei, Taiwan, 7 th March 2010. Agenda. The Team. Alex Voss School of Computer Science University of St Andrews Andy Turner School of Geography University of Leeds
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Social Simulation Tutorial International Symposium on Grid ComputingTaipei, Taiwan, 7th March 2010
The Team • Alex VossSchool of Computer ScienceUniversity of St Andrews • Andy TurnerSchool of GeographyUniversity of Leeds • Rob ProcterManchester e-Research CentreUniversity of Manchester
Aims of the Tutorial • To provide a brief introduction to agent-based simulation, population reconstruction and RePast Simphony. • To motivate the use of grids and clouds for running social simulation ensembles • To demonstrate use of grids and clouds and provide practical instructions for running your own models • Not to replace RePast tutorial!
Practicalities • Using your own laptop • Participant sheet with login • URL for instructions: https://e-research.cs.st-andrews.ac.uk/SimISGC2010 • Download software and certificates from local server (see URL above) – also USB sticks to pass around • Using GILDA training infrastructure
Background • Much social science does not use advanced ICT but emergence of new analytical methods is driven by: • Increased availability of data about social phenomena • But data is ‘messy’, anonymised, aggregated, incomplete • Challenges to analyse social phenomena at scale • Challenges to inform practical policy and decision making (e.g., evidence-based policy making)
What is Social Simulation? • A new approach to modeling social phenomena • Based on empirical data • Based on existing theories • A new way to explore them, complementing other forms of modelling and prediction • Used to understand and predict • Not just one form of simulation: systems dynamics, microsimulation, queueing models, etc.
What is Social Simulation? (II) • Models necessarily incomplete • There can always be more detail • Higher spatial and temporal resolution • More and more detailed attributes • Geography and social science is no different to any other type of science in this respect • Need to assess impact of decision about how to model
Simulation as a Method Model Simulated Data Simulation Implementation and Verification PopulationReconstruction Model Validation Abstraction Collected Data Data Gathering or Re-Use Target Adapted from Gilbert & Troitzsch, p. 17
What is Agent-Based Modelling? • Simulating interactions between dynamic populations in changing environment • Heterogeneous populations – each individual has specific attributes such as age, gender, socio-economic status, health, etc. • Stochastic process – each run can differ from previous • Notion of emergence – larger-scale phenomena produced through many small interactions / events • Sets of simple rules produce complex behaviour – sets can be large… • Can help model and analyse phenomena too complex for closed form, can be used in absence of knowledge about causality
ABM Frameworks • Rapid growth over last 10 years • Many implementations • General frameworks (open source): • Swarm • MASON • NetLogo • Repast • Repast Simphony • Aim to separate concerns clearly to maximise modeling capability
ABM Conceptual Components Agents Context Behaviour Relationships Environment
Building Simulation Models • Model Design – about the choices made, cf. research design • Model implementation – cf. research method (‘the logistics’, ‘plumbing’) • Verification – checking the implementation matches the design • Validation – checking the design represents the aspects of the world modeled
Building Simulation Models (II) • Simple models can be built using graphical editors (cf. RePast tutorial) • More complex models and behaviours inevitably require programming • Data management etc. become important as size grows • Calls for interdisciplinary collaboration, division of labour see above
Trust in Models • Scientific codes often many years old and carefully maintained • Social simulation is in its infancy – relatively speaking • Need to build community development approaches that produce robust, reliable code • Yet need for flexibility and adaptability – research is about doing things not done before…
Social Simulation: Reading • Nigel Gilbert and Klaus G. Troitzsch: Simulation for the Social Scientist(cress.soc.surrey.ac.uk/s4ss/) • Joshua M. EpsteinGenerative Social Science:Studies in Agent-Based Computational Modeling(http://press.princeton.edu/titles/8277.html)