This paper is a challenge to Jay Forresters Urban Dynamics model. The resulting alternative model is compared to Urban Dynamics by running tests of actual U.S. Housing policies.
The traditional way of teaching strategic management at business schools is the case method. While it aims to provide a simulated environment for strategy formation, the case method has several limitations. Many of them can be overcome through the use of Management Flight Simulators (MFS) by combining computer simulation models with conventional case studies. While many existing MFS focus on specific industries, we developed an Industry Evolution Management Flight Simulator that captures the generic industrial structure with endogenous firm entry and exit. For effective teaching purposes, we then introduced staged game design, and tested both the MFS and supporting materials and pedagogy in strategic management classes at the MIT Sloan School of Management. We started with a version for a relatively simple competitive situation, represented by the salt industry, with pricing as the only decision variable. Later in the course we introduce a version for a more complex strategic setting, represented by the video game industry, where players make multiple decisions and where additional feedbacks are relevant, including network effects, complementary assets, and pricing in both the console and cartridge markets. Preliminary results are discussed.
Successful implementation of innovations is central to social service organizations effectiveness and improvement of services to clients. Yet administrators face a host of challenges and implementation failures are common. This paper discusses the nature of the innovation implementation as inherently dynamic, endogenous to the organization, and constrained by conditions of bounded rationality. Several system dynamics models of innovation implementation are reviewed from manufacturing, health, and human services in terms of their appropriateness and evidence base for social services. Recommendations for practice and a research agenda offered.
This poster reports on the preliminary results of a study comparing the effectiveness of system dynamics with traditional, lecture based, methods of learning about wetland ecosystems. The study tests the hypothesis that students utilizing a system dynamics approach learn more and retain more of the material presented to them than with the traditional teacher-based approach. Students from the Las Vegas school district participate in one of two treatments, as the experimental or the control group. Students in the experimental group are presented with a lesson utilizing four system dynamics models about the Wetlands Park Nature Preserve (WPNP) in Las Vegas, Nevada. Students are given a pretest, prior to instruction, and a posttest two weeks after instruction. To assess student learning, understanding, and retention, scores on the pre and posttest are analyzed.
Modeling assistance is available at the conference to enable modelers to discuss their specific modeling questions with modeling coaches. Modeling assistance opportunities include two workshops, as well as the possibility of assistance at any time during the conference. Assistance is available for modelers with all levels of modeling ability, from beginner to advanced, with questions about a specific model that modelers are developing or studying, to something that modelers don't understand in one of the system dynamics textbooks or software packages. Questions may range from problem articulation, formulation of a dynamic hypothesis, formulation of a simulation model, model testing, or policy design and evaluation. Modelers should bring whatever materials they need to describe their modeling question, including pencil and paper, books, posters, or laptop computers. Spectators are welcome to observe modeling assistance coaching sessions.
A system dynamics simulation model was developed for understanding trends in obesity in the United States. Data on population body weight from 1971-2002 were combined with information from nutritional science and demography into a single analytic environment for conducting simulated policy experiments. Interventions among school-aged youth and others were simulated to learn how effective new interventions would have to be to alter obesity trends; which population subsets ought to be targeted; and how long it takes for those actions to generate visible effects. One finding is that an inflection point in the growth of overweight and obesity prevalences probably occurred during the 1990s. Another is that new interventions to assure caloric balance among school-age childreneven if very effectivewould likely have only a relatively small impact on the problem of adult obesity. More comprehensive efforts at all ages are needed to avoid the high costs and heavy burden of disease due to adult obesity.
In this paper an application of the System Dynamics approach in the field of energy supply is presented. Decentralized energy supply is introduced as a new energy system with a high potential for meeting ecological requirements and sustainability targets. System Dynamics models of one power supply unit (PSU) and of the decentralized energy supply (New Energy System Model) are described. The electrical and thermal power flow and the power conversion processes represent the basis for the stock-and-flow diagrams. At any time and for every sub process of the overall system the precise power and energy state can become certain and comprehended for the user. With examples some results of simulation are represented. Investigations of technical and ecological potential of decentralized energy supply systems are the primary objective of the models. The models are also used for education purposes for the elucidation of energetic supply processes with different power station technologies.
On 21 September 1999 at 1:47 am, an earthquake measuring 7.3 on the Richter scale struck central Taiwan, causing serious damage and loss of lives. As of February 2006, only 70% of the reestablishment work has been completed. With rapid advances in urban development, the destruction incurred by earthquake disasters increases both in extent and severity. With the aim to minimize loss in human lives and properties caused by natural disasters, this study probes into the urban disaster prevention mechanism, examines the problems encountered in disaster prevention and strategies for prevention. A system dynamics model is established to simulate changes in the disaster prevention system on the basis of related statistics and survey data of September 21 Earthquake. Strategies for urban planning, development and management are suggested from the perspective of disaster prevention. The simulation analysis can offer valuable insight to policy-makers for assessing and deciding on the most feasible and effective strategies to be implemented.
Modeling contagious diseases has taken on greater importance over the past several years as diseases such as SARS and avian influenza have raised concern about worldwide pandemics. Most models developed to consider projected outbreaks have been specific to a single disease. This paper describes a generic System Dynamics contagious disease model and its application to human-to-human transmission of a mutant version of avian influenza. The model offers the option of calculating rates of new infections over time based either on a fixed reproductive number that is traditional in contagious disease models or on contact rates for different sub-populations and likelihood of transmission per contact. The paper reports on results with various types of interventions. These results suggest the potential importance of contact tracing, limited quarantine, and targeted vaccination strategies as methods for controlling outbreaks, especially when vaccine supplies may initially be limited and the efficacy of anti-viral drugs uncertain.
Why is health reform so difficult to achieve in the US? When it does succeed, what factors contribute to its success? This paper extends a causal model presented last year to include political and other factors that help to answer these questions. The paper examines the experience of several states in the US as they have struggled with a key aspect of health reform, extending insurance coverage to children, families, and other groups that are uninsured. . It also draws from other models that have been applied to understanding political and social change. The causal analysis that is presented emphasizes the importance of making policy choices in shaping proposed reforms that fit within a window of opportunity presented by the states political and economic environment. The paper concludes by suggesting that expanding access must be viewed as an ongoing process in which early successes create opportunities to benefit additional people.