The problems we are facing at all levels in the world today are growing more intractable. In particular, our problems are becoming increasingly resistant to unilateral solutions. I will argue that this growing resistance and intractability result from the fact that while the evolving web of interdependencies, of which we all are part, is rapidly tightening, the development of our capacity for thinking in terms of dynamic interdependency has not kept pace. As the gap between the nature of our problems, and our ability to grok this nature grows, the planet will face increasing peril on a multitude of fronts. System Dynamics and System Thinking -- the larger framework of which it is a subset -- are an important part of an effective strategy for closing the gap between challenge and capacity for addressing challenge. Unfortunately, we as System Dynamacists and Systems Thinkers have been woefully inadequate in transferring our framework, skills and technology to the population at large. Although we have “seen the light” for some thirty years now, we have not opened the door to our inner sanctum wide enough to let others share in our insight- generation capabilities with respect to the inner workings of closed-loop systems. In order to be more effective in transferring our very valuable capabilities to a broader swath of humanity, we need to see more clearly precisely what these capabilities really are, and also to understand the forces driving the evolution of the education system into which these capabilities -- if they are to be transferred on a board scale -- must be assimilated. My purpose in writing this paper is to shed some (hopefully new) light on both what it is we have to bestow, and also on where the educational system that is to receive our bounty is headed. My intended audience therefore is both Systems Thinkers and educators. My highest hope for the paper is that it will serve to further eradicate the distinction between the two.
Successful welfare reform is difficult to achieve in practice and to study in theory because the linkages between policy reforms and the actions of clients of the system are many, long, and loose. Reformers can change organizational structure, funding amounts and requirements, as well as mandates. They hope that these reforms will change the behavior of workers who will implement the reforms. In turn, changed behavior of employees and welfare agencies are presumed to change the behavior of clients. Evaluating welfare reforms requires that information about policy changes, organizational changes, changed behavior by workers, and ultimately changed client behavior all be examined empirically and the results combined into a coherent whole.This paper proposes that system dynamics models may be a new tool in the analyst’s toolchest that can help to create integrated theories of welfare reform as well as help to integrate results from empirical studies of welfare reform. Below we present a first cut system dynamics model of the implementation of portions of the welfare reform legislation of 1988. This effort is designed to illustrate how system changes, changes in worker behavior, and client behavioral choices might be simultaneously analyzed within the context of a singe feedback system. Of course, the hard work of elaborating and empirically validating the structure of this simple model still remains before us.
In previous papers, various approaches to studying the relationships between an aggregate dynamic model and an underlying, stochastic system have been reported. These approaches include the use of a Master Equation model to derive the aggregate model from stochastic hypotheses, and the summation over a population of dynamic sub-models to estimate the aggregate behavior. In this paper, a commodity cycle model is re-formulated as a stochastic, discrete simulation model to study the effects of stochasticity on the aggregate behavior of the system. Global variables provide aggregate information links to control the arrival and departure of new entities (commodity units and capacity units). A comparison of the aggregate dynamics of the stochastic and the equivalent system dynamics models is made under conditions in which the dynamic models is made under conditions in which the dynamic model is oscillatory and undergoing period-doubling bifurcations leading to chaos.
PASION is a process- and event-oriented simulation language designed for those who already know and use PASCAL. The language has a two level (process/event) structure and permits the use of all the Pascal Structures. It also offers the main features of object-oriented programming. PASION provides necessary facilities to handle sequences of random events, queues and quasi-parallel processes, both discrete and continuous. A PASION source program consists of a sequence of process declarations and a main segment which initializes the simulation. At run time the program generates objects which represent model processes due to the process declarations. PASION provides tools which facilitate the building of complex models by the mechanism of inheritance.
Building large dynamic simulation model of an industry requires sound organizing principles and appropriate tools combined with a thorough understanding of the industry being modeled. In this paper I will describe how we build a simulation model for a client’s business to answer the client’s key strategic questions.The models are large because they are based on physical, observable phenomena in the industry. They must take into account the stocks and flows of product and money as well as represent managers’ decision-making processes and the key variables that impact each producer’s decisions. Most corporate decisions are based on physical or financial parameters, so the model structure is clearly understandable to the final user.At Federal Group we use an effective methodology for building large-scale structural dynamic simulation models to address the real world problems of business decision makers. This paper presents how we have successfully constructed such models for oligopolistic, capital-intensive industries. However, our methodology can be generalized to a broad range of other business environments.
Behavioral simulation models of OPEC have typically been built on the assumption that OPEC price changes are determined by capacity utilization. We evaluate this model by examining its empirical and behavioral justifications, and by observing how it performs in a simple world oil market model. We also briefly explore and evaluate alternative behavioral rules for OPEC.
The paper presents some results of research regarding the relationship between the centralization degree and the efficiency of economic systems. A simple system dynamics model has been used in these studies. The model has applied certain J.Kornai’s ideas concerning economic systems. Simulation experiments have confirmed the viewpoint that overall economic behavior arises from within feedback loops creating microstructure of each system. Two basic kinds of microstructure have been distinguished: centralized and decentralized. Macro behavior generated by them is close to these observed in planned and market economies. The paper is divided into four parts. In the first one, basic Kornai’s ideas are outlined. In the second part, model is presented, whereas in the third one, some results of simulation are analyzed. Conclusions drawn from the experiments are presented in the fourth part.
In this study, a decision support system for system dynamics modeling is designed. The intelligent part of the system is composed of a knowledge base, a data base and an inference engine. The function part of the system is composed of some modules for model construction, model generation, model simulation, model interpretation, model management, and PD interface. The proposed system is a production system written in PROLOG, and it can join up with the professional Dynamo plus software by means of the PD interface. Whole process from modeling to simulation can be realized by the support of the system. An application example is given in this paper.
Negotiating group can use generic computer tools to aid decision-making and problem solving activities in negotiation management. In attempting to create, apply, and evaluate such computer tools, the authors have had to address the issue of user acceptance. This paper reviews the basic framework of negotiation management and locates the issue of user acceptance within that framework. Focusing on system dynamic simulation models as tools for negotiators, the paper analyzes the reactions of potential and prospective users.
The issue of global warming has sparked debate among scientists and policy makers over the last two years. Many studies have been undertaken in the U.S. and other nations to determine the potential severity of global climate change and appropriate policy responses.The U.S. Department of Energy is now conducting one such study of energy technology and policy options to mitigate greenhouse gas emissions. The study is an attempt to assess the emissions reductions potential and costs of several policies, using the FOSSIL2 integrated energy model. This paper focuses on preliminary results of a subset of eight policy cases. It discusses the modeling methodology, the formulation of these policies, draft results and some policy insights gained.