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this is work in progress, which deserves a lot more thinking and elaboration, still ....

this is work in progress, which deserves a lot more thinking and elaboration, still ....

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  • 1. Some thoughts on design research, models and simulations Peter SloepFriday, May 4, 12
  • 2. Overview • Part I: ‘ordinary research’, the essentialia • Part II: design research, the differences • Part III: modelsFriday, May 4, 12
  • 3. Caveat • A quick and dirty introduction to some aspects of the philosophies of science and technology • Sometimes less than accurate, sometimes plain wrong, but always in an attempt to be useful.Friday, May 4, 12
  • 4. Ordinary research, aimed at understanding and controlFriday, May 4, 12
  • 5. Theoretical models Ia Ib S1 S2 S3 IcFriday, May 4, 12
  • 6. Theoretical models smoke therapy Ia Ib S1 S2 S3 healthy Ic cancer dead therapyFriday, May 4, 12
  • 7. • for a model to be useful, you need • descriptive apparatus, vocabulary • rules for how to use it, grammar, syntax • rules that uses the vocabulary and syntax to describe possible model behavioursFriday, May 4, 12
  • 8. • rules about possible behaviours are interesting • they are generalizations, subsume instances of model behaviour • form: whenever X then YFriday, May 4, 12
  • 9. • all kinds of vocabularies and syntaxes • math.: diff. equations, finite automata, probability calculus • computer languages: Stella, Netlogo • ordinary language (but formal languages are much more powerful because they allow inferences from axioms)Friday, May 4, 12
  • 10. What use are models? • Are the generalizations true of the world? • you test a model • predict future behaviour, check if it occurs • yes: more confidence • no: adapt or fully reject modelFriday, May 4, 12
  • 11. • A word on statistics • some models are stochastic, their behaviour is stochastic • but all data are subject to chance variation; you use statistics for the latter, to quantify uncertainty in your decision to accept the model or reject itFriday, May 4, 12
  • 12. What use are models? • Are the generalizations useful in the world? • you explain the world by using model generalizations on phenomena • you control the world by using the model to predict phenomenaFriday, May 4, 12
  • 13. Design research, focused on artefact design for controlFriday, May 4, 12
  • 14. • artefacts are designed and developed to help control the empirical world • there always are desired phenomena, the artefact causes them to occur • there thus is a targeted state of the world and an obtained state of the worldFriday, May 4, 12
  • 15. St Si So IFriday, May 4, 12
  • 16. • building an aeroplane to fly • setting up an organization (bank) to lend money to investors • building a learning network to facilitate competence development, creativity and knowledge sharing of non-formal learnersFriday, May 4, 12
  • 17. Artefactual models • As the artefact is to perform a function, you now build a model that describes the artefact’s behaviour, using bits and pieces of relevant theoretical models • Such a model I call an artefactual model, to distinguish it from theoretical modelsFriday, May 4, 12
  • 18. Test • to the extent it incorporates theoretical models, confidence carries over from them • to the extent it rests on untested assumptions (structural and parametric) you test it • experts, independent tests • you thus contribute to theor. model dev.!Friday, May 4, 12
  • 19. Simulate • Use the artefuactual model to explore the artefact’s behaviour through simulations • Empirical tests are costly, dangerous, unethical, etc. • Simulations are pseudo-performance tests of the artefact • They may lead to design improvementsFriday, May 4, 12
  • 20. Empirical test • Carry out empirical tests of artefact performance • effectiveness - gap between actual and desired behaviour • efficiency - costs of obtaining desired performance level increase • sustainability - costs of maintenanceFriday, May 4, 12
  • 21. HowFriday, May 4, 12
  • 22. Model ingredients 1. identify the system and its boundaries: draw a causal network 2. identify variables and constants 3. identify state variables (‘laws of succession’, variables that describe state transitions) and and input variables (variables that drive change)Friday, May 4, 12
  • 23. 1. choose output variables, what changes you want to measure (could be a state variable) 2. choose a suitable modelling language • analytic, using math. equations, often differential equations • numerical, using computers, dedicated language, e.g. Netlogo, Stella, Brahms, ...Friday, May 4, 12