Few real life case study examples exist concerning optimisation in system dynamics models. This study reports an attempt to estimate relevant parameters of an AIDS spread model in order to check whether the chosen model structure can be separately parameterised and thereby explain the course of the epidemic for more than one country. The UK and USA are the two countries selected and the parameter values derived are reported for each. The values obtained are not inconsistent with emerging knowledge about the epidemic and the subsequent optimised projections reveal that the peak of the homosexual epidemic has been or is about to be reached in both countries.
Ongoing research in the Rockefeller College of Public Affairs and policy is focusing on strategies for efficient and effective model building in groups. The intent is to involve a relatively large client group in the business of model formulation, not just conceptualization. Recent projects have explored strategies for accelerated group model building in the context of two public policy problem areas: the burgeoning cost and caseload of foster care in New York State, and recent unexplained increases in Medicaid costs in the state of Vermont.Five roles appear to be essential to support effective group model building efforts. We term the five roles the facilitator, the content coach, the process coach, the recorder, and the gatekeeper. This article identifies the five roles, briefly overviews the two problem areas, sketches the design of the group model building efforts, outlines the apparent results, and hypothesizes principles and strategies to guide future group modeling efforts.
Studies of chaos in foreign exchange markets often lack a theoretical underpinning. This paper tries to give some reasons why exchange rate movements may become chaotic. Starting from an assumption about different groups of traders that goes beyond recent models of fundamentalists’ and chartists’ behaviour it argues that, to capture the idea of chaos, foreign exchange markets have to be modelled as a dissipative system and not, as usual, as a closed conservative one. A qualitative system dynamics approach is chosen to demonstrate the complex interaction processes arising.
This paper refers to the assumption that the major paradigm of System Dynamics, General Systems Theory, is not able to provide adequate models of organizational learning processes. It is shown that the theory of self –referential systems is able to overcome current theoretical weaknesses: Considering the difference between communication, the basic operation of social systems, and thoughts, the basic operation of psychic systems, a framework for organizational learning is proposed. Consequences for the management of organizations, especially their strategic change resp. the building of learning organizations, are discussed.
During the first years of the 80’s decade, the continual financing of the argentine deficit fiscal, throughout the emision of new money, pushed Argentina to the verge of hyperinflation. In June 1985, the seriousness of such a situation compelled the governing party, the Union Civica Radical, to adopt hard policies of stabilization, afterwards known as Plan Austral. In this article a SD version of a small dynamic model is presented – in Cagan’s tradition (1956), conceived by Fernandez and Mantel (1985)-of the mentioned Argentine stabilization process. Dynamic simulation is used to analyse the macroeconomic behaviour.
During the process of system dynamics modelling of organizations, policies or problem, R-mode (so called “right brained”) procedures, such as the JOG exercise, seem especially relevant (1) in the early phases, when an elicitation of ideas, variables, considerations and concepts having possible relevance is undertaken, and (2) during any of the modelling phases, when an unbiased evaluation is desired, perhaps in addition to more traditional: “objective” L- Mode assessments. JOG is described, as it was employed with top and middle managers of a small US hotel chain, in developing a preliminary system dynamics model for a new corporate vision.
Although computer simulation modeling has long been used to study issues in peace and world order, it has not resolved the controversy surrounding peace research. The problem is the lack of a well-defined methodological rudder to guide the modeling process. In this paper, a new methodological approach to the study of peace and world order is proposed, and its merits discussed. This approach is a synthesis or marriage of institutional economics, system dynamics computer simulation modeling, and peace and world order studies.
The rapidly growth of trade industries on the developing countries can be predicted that on the near future occurs many problems, especially the problems like as piling up by the goods at the port and passing over of capacity by the trucks at the road. These problems can be solved by the improvement on both a port and a road. However, it is suggested that because the budget constraint these regards can not be conducted at the same time. The scheduling projects strategy which priories the vital projects as the first implementation is the one technique that can be considered. However, to appraise the economic impact of this implementation, an existing trade industries system model is required. This appraisal is an interesting regard as the consideration for the planner in case to decide the better transportation planning. Based on the existing trade industries, this paper proposes a model which can appraise the economic impact of the scheduling transportation projects by using System Dynamics Methodology.
This paper describes a methodology for manpower planning in health care. The methodology is applied in the field of rheumatology. This methodology uses the concept of political rationality: different actors with different mental models, goals, languages and power interact in a bargaining process with incomplete and imperfect information. A Group Decision Support Systems approach is advocated where interactive model building stimulates shared meaning and communication. In health care important decisions usually have a multi-level and multi-actor character. A bottom up procedure, starting at the detailed level gives a justification when aggregating to an higher level. Consequently the project was started with discrete event models before applying continuous simulation like system dynamics. Besides the modelling and communication processes the creation of a network of key decision makers in health care applying this approach is seen as a major product.