On the scenario approach to simulation modeling for complex policy assessment and design

This paper reviews the major issues posed by scenario-based simulation modeling in the policy process, using agricultural policy as an example of a complex decision arena. Policy is seen as a process by which decision makers use the instruments under their control to approach the general goals of society. Models can help to choose instrument settings, evaluate policy options, and assess their appropriateness to a particular situation. But they cannot design policy; the interactions between policy makers and models are critical if modeling is to be useful in the policy process. Policy models must be oriented to the factors that focus and constrain judgments in the real world, as well as toward the substantive problems motivating analyses. These include the actors within the system, as well as the geographic and disciplinary contexts of the problems. Scenario-writing provides a way of ordering understanding and judgment about different phenomena to help users interact most effectively with a model and to insure that the perspectives of the model are most appropriate to the needs of the decision-maker. It is an iterative and evolutionary process which can provide a great deal of insight into the assessment phase of policy design