Nonlinear differential equation systems of the kind used in system dynamics are capable of exhibiting highly irregular, erratic, turbulent or “chaotic” behavior. Conditions for the existence of this phenomenon are discussed and their application in dynamic socio-economic modeling explored. In particular, irregularities in economic cycles might be explained by nonlinear feedback effects in contrast to the usual “random shock” model. Dynamo simulations are used to illustrate the basic concepts involved. The view, often emphasized by Forrester, that policy should not be based on level predictions but should focus on regulating qualitative modes would seem to be strongly supported. The positive economics position associated with Friedman that theories should be judged on their predictive performance would now appear to be too restrictive. Instead, the system dynamics view that the plausibility of model assumptions should be the main basis for establishing theory credibility is strongly reinforced.
At the beginning of the seventies, grave concern existed over low mobility of researchers due to the stagnation in growth in the research capacity available. Through a strong expansion in research capacity prior to this condition of stagnation, the age of researchers was relatively low. It was feared that the small natural turnover (as a result of a low average age) together with the low mobility would lead to a collective aging of the research corps itself. This aging factor was considered to be a threat to research as a whole since it could lead to mental fixation and loss of creativity. In addition to this, the expectations for making a career and the employment possibilities open to the then recently graduated university students had strongly decreased. This situation resulted in a loss of talent for research groups, and it was feared that there would be a decline in the motivation and development possibilities for researchers. The developments briefly described here formed no phenomena exclusive to the Netherlands but also made their appearances in substantially all of the western countries.
Any firm or industry which experiences marked cyclical fluctuations in both output and demand can provide a testimony of the damaging effects such oscillations have on profitability. Perhaps none more so than the British Steel Corporation (B.S.C.) whose record in this respect is rather poor. For such industries, therefore, any methods which management science can provide as a means of analysis of the causes and effects of such cycles are to be welcomed. It is suggested in this paper that system dynamics provides an important framework for analyzing the causes of cyclical behaviour in economic systems and that it is this area of application which possesses the greatest chance for successful demonstrations of its use. It is probably for this reason that work using the methods of system dynamics has concentrated, in Gt Britain, on economic systems.
In large numbers of U.S. urban elementary schools, there is a multiplier effect which operates to reinforce high achievement for initially high-achievers, average achievement for initially average-achievers, and failure for initially low-achievers. This problem is aggravated by the fact that initial levels and perceptions of achievement are systematically related to social class. In part, poor children enter school with less readiness for reading. Evidence also suggests that, actual achievement aside, teachers tend to perceive lower class children as low-achievers simply because they exhibit lower-class family, dress, and behavioral characteristics. In contrast, there are a relatively small number of “lighthouse” schools spread through out the country in which students, often minority and/or poor, achieve far better than home or SES variables would predict.
This paper deals with the structure of the system of arms transfers by the United States to the rest of the world. Arms transfers play a significant role in the political, economic, and military affairs of most countries. Because of the diversity of opinion about the necessity for transfers and their true effect, a single policy concerning arms movement has been impossible to devise. This research is the first step in providing a model that can be used to study the effects of transfers and to evaluate policy concerning arms movement.
The world oil market is undergoing substantial changes, in terms of overall structure, number of key participants, and market adjustment mechanisms. These changes will influence both price determination as well as critical decisions pertaining to the production capacity utilization.
In this paper, a pilot system dynamics simulation model, EDFIN1, is used to forecast the impacts of a cost-of-education index (COEI) on patterns of per pupil expenditures across various types of local school districts. Originally designed to compensate more fully those districts that incurred greater costs in the purchasing of educational inputs (i.e., higher teacher salaries or greater need for transportation), COEI adjustments are seen also to have direct impacts on the relative equity of per pupil expenditures across the states as a whole.
This paper contributes to the discussion of academic training requirements for System Dynamics modelers. In particular, it suggest that training in Strategic Management can provide the System Dynamics modeler with some essential complementary tools and a “top management perspective” (or systems viewpoint), which is needed to define problems of real managerial interest. To illustrate these points, the author describes his experiences in defining a problem for system dynamics modeling. The future prospects for the New Zealand Forestry Sector, and the New Zealand Forest Service, are described and the problem for modeling is presented.
To introduce system dynamics approach into interprofessional organization to built a model about agricultural market is not so original. That’s more interesting is the use of system dynamic to define what information system must be not only designed but scheduled to regulate the market. Since July 1979, MEDOC gives some useful informations to people who have the difficult challenge to follow the Bordeaux wines market.