System simulation and policy-making for economic development

These problems are characterized by the uncertainty necessarily inherent in any process of planning for the future, uncertainty arising both from the quantity and quality of available data and from the difficulties of forecasting how a large-scale system of complex interactive and feedback relationships will respond to policy inputs. In this paper, generalized system simulation is offered as an approach to dealing with these problems. It is a flexible, iterative, problem-investigating process that includes problem formulation, mathematical modeling, model testing and refinement, and application of the model to solve problems all in close consultation with decision makers. As an illustration, an overview will be given of a policy-oriented system simulation model of the Nigerian economy. The model consists of two detailed regional agricultural submodels, an aggregated national nonagricultural submodel, and components which model Nigeria"s population and the interregional trade in food