Problem Articulation (Boundary Selection) • Theme selection: What is the problem? Why is it a problem? • Key variables: What are the key variables and concepts we must consider? Time horizon: How far in the future should we consider? How back in the past lie the roots of the problem? Dynamic problem definition (reference modes): What is the histo cal behavior of the key concepts and variables? What might their behavi be in the future? 2. ormulation of Dynamic Hypothesis problem Initia atic behavior? • Endogenous focus: Formulate a dynamic hypothesis that explains the dynamics as endogenous consequences of the feedback structure. • Mapping: Develop maps of causal structure based on initial hypotheses, key variables, reference modes, and other available data, using tools such as . Model boundary diagrams, • Subsystem diagrams, . Causal loop diagrams, • Stock and flow maps, • Policy structure diagrams, • Other facilitation tools. 3. Formulation of a Simulation Model . Specification of structure, decision rules. • Estimation of parameters, behavioral relationships, and initial conditions. • Tests for consistency with the purpose and boundary. . 4. Testing • Comparison to reference modes: Does the model reproduce the prob lem behavior adequately for your purpose? • Robustness under extreme conditions: Does the model behave realis tically when stressed by extreme conditions? • Sensitivity: How does the model behave given uncertainty in parame ters, initial conditions, model boundary, and aggregation? ….Many other tests (see chapter 21). 5. Policy Design and Evaluation • Scenario specification: What environmental conditions might arise? • Policy design: What new decision rules, strategies, and structures might be tried in the real world? How can they be represented in the model? • “What if…”analysis: What are the effects of the policies? Sensitivity analysis: How robust are the policy recommendations under different scenarios and given uncertainties? • Interactions of policies: Do the policies interact? Are there synergies or compensatory responses
