The problem of empty houses in Taiwan continues to concern the public. The Government currently conducts housing survey to detect the number of empty houses every year. But, no systematic analysis of the monitoring and early warning programme has been undertaken to improve the situation. This study formulated dynamics and genetic artificial Neural Network models for the monitoring and early warning system stimulating. Several strategy scenarios were conducted. The research findings showed that economic strategy has a more positive and profound impact than financial one; combined strategy often has a better policy assessment compared to a single strategy. The method developed in this study is a comprehensive and systematic approach to achieve the sound housing market in Taiwan.
Health system reform is a national priority in the U.S., but it is increasingly being pursued through a mosaic of local initiatives. More and more concerned leaders in cities, towns, and regions across the country are working within their local health systems to achieve better health, better care, lower cost, and greater equity. Such ambitious and widely dispersed ventures, however, are hard to plan, unwieldy to manage, and slow to spread. Further progress could occur if diverse stakeholders were better able to play out intervention scenarios, weigh trade-offs, set aside schemes that are unlikely to succeed, and enact strategies that promise the most robust results. Through the Rippel Foundations ReThink Health initiative, veteran leaders and creative methodologists are learning what it takes to spark and sustain system-wide improvements in different settings. Interactive simulation modeling and game-based learning support innovators by bringing greater structure, evidence, and creativity to the action planning process. In this paper we provide an overview of the ReThink Health Dynamics simulation model by providing a summary of its structure, intervention options, data sources, user interface, experiences in pilot sites, initial insights, evaluation plan, and possibilities for further development and diffusion.
Organ transplantation is a lifesaving procedure for many people. However, the lack of organs from deceased donors makes it unavailable for many additional people who need it. A commissioned study was undertaken to estimate deceased donor potential in the US. Organ procurement and transplantation take place in the context of a complex system of organizations and policies. This system can both constrain and enhance the realization of deceased donor potential. A system dynamics model is being developed to help identify how that systems behavior affects the availability of deceased donor organs and how particular strategic policy options might increase the number available for transplantation. The structure and data sources for the model are described along with illustrative tests of those strategic options.
Fast growing electricity demand in Indonesia has threatened countrys economic development pace. However, government owned Electricity Company cannot cope with this growing demand. As a result they rely on Independent Power Producer (IPP) which harm government budget. In the mean time, government realizes this growing issue and tries to do something by building more power plants. On the other hand, their plan on building new coal and oil based power plant is meeting a lot of resistance from NGO and parliament. On top of it, government cannot afford continue funding electricity from IPP. The situation is increasingly become worse if government does nothing about the issue. Therefore, understanding and smooth communication is needed to provide solution for the issue. A system dynamics based game is built to foster communication between stakeholders, in order to help them visualize dynamics and feedback loop inside Indonesias electricity system. In the first development phase the game tested on group of students and showed good result on improving their understanding on current electricity issues.
Quantifying the strength of causal loops on a stock can help bring insights into the relationship between model structure and behavior. This paper uses mathematics to derive loop strengths in a number of generic small models using the relationship between the second and first derivative from the Pathway Participation Metric method. The loop strengths are plotted in a System Dynamics (SD) simulator together with the stocks to help explain behavior in the Limits to Growth, Predator-Prey, Diffusion and SIR models among others. Issues such as loop dominance, flow dominance and the change of polarity of higher order loops are used to explain behavior. In particular the identity of the causal loops in the Diffusion and SIR models are discussed and compared with previous work. Finally a numerical method for computing loop strengths and identifying dominant loops within an SD simulator is presented and applied to the Yeast Model. It is hoped that the paper will inspire others to use loop strengths in their analysis and understanding of SD models
Recent trends in demographic changes in Germany mainly because of rapid population ageing represented as increasing ratio of older population over total population, have become a major problem for the German government. They are worry if recent trends continues it would cause massive disturbance in Germany socio-economic system, starting from vast amount of pension fund government have to pay to immerse fall of countries GDP. Therefore, by using System Dynamics approach this paper offers systemic point of view on how population structure changed in Germany; it explain why fertility rate in Germany stays low and how economic indicators would trigger changes in population structure. Moreover, it also illustrates feedback effect from population age structure to economic indicators. The result shows that current trends will continue and will not dampen if there is no adequate policy intervention from government. Hence, this paper offers set of policy measures to stabilize increasing ratio of older population. By opening more immigration opportunity for productive age workers, increasing child incentives, increasing pension age, and promoting gender equality as a set of policy measures might exhibit a better result to stabilize the population age structure. This policy measures effect shows desirable result toward expected behavior.
Firms have long used strategic foresight to adjust to fast changing business environments and increasing uncertainties. While strategic foresight on a corporate level is rather common, approaches addressing the network perspective are still rare. Documented attempts within the last few years to combine different foresight methods indicate a need for integrated approaches. Methods to communicate and discuss future thoughts between strategists and decision makers engaged in foresight processes gain importance. The goal of this paper is threefold. First, to present a strategic foresight approach that evaluates key drivers of future changes. This evaluation is conducted based on a firm's business model by considering the network perspective. Second, the application of the approach is shown with focus on the development of a system dynamics model during a group model building process. Third, a generic system dynamics model for performing strategic foresight in production networks is introduced.
The purpose of this paper is to investigate whether stock/flow failures persist in naturalistic decision making environments. A tangible stock/flow experiment is used in this study, which asks participants to pour a certain amount of water into a glass through a funnel in an as short time as possible. Findings are that people on average do not perform better in a tangible stock/flow task than in a computerized or paper-based test of a comparable task. In addition, individual performance in the tangible task cannot be related to performance in a similar paper-pencil stock/flow task. An implication of this study is that naturalistic stock/flow tasks are as difficult for humans to control as more abstract tasks. Further research should address individual differences between the two modes of task (tangible vs. paper-based). A limitation of this study is the usage of one tangible stock/flow task only. The value of this paper lies in the combination of a standard test with a tangible experiment addressing the same cognitive capabilities.
Different approaches to model feedbacks in financial systems are assessed based on requirements for the conceptualization of the feedback dynamics. Given the non-linear, behavior driven, and interconnected characteristics of systemic financial feedbacks (SFFs), modeling concepts from System Dynamics (SD) theory provide appropriate and attractive features. Surprisingly, few SD models exist to explain systemic financial feedbacks. The scarcity of SD modeling for SFFs may be attributed to the lack of required economically-sound foundations for theoretical modeling. This paper considers a conceptual framework for SFFs that emerges from the synthesis of formal principles of economics and SD. In doing so, this study links existing SFF models to concepts of SD and provides suggestions for further modeling.
This paper describes the role of systems modeling in the National Parks. The parks have been described as Americas Best Idea, and they are celebrating their 100th year anniversary. Systems thinking and systems dynamics can help the parks plan for the second century.
This paper presents a review of the criticisms of system dynamics and assesses the validity of these against recent findings in the field. The authors survey the literature critical of system dynamics and review their criticisms using the current understandings in the system dynamics field. This work suggests that there are some pertinent criticisms that have been aimed at system dynamics. These include the apparent disagreements regarding the role of historical data in model confidence building, system dynamics' reductionist perspective and how system dynamics addresses plurality and hierarchy. Overcoming these criticisms require the ever present need for education, communication and theoretical work. It is hoped this paper will strengthen the mandate of system dynamics in the eyes of its critics, assist and improve the field and its general acceptance as a tool of analysis.
System dynamics unmistakably has perfect innate capabilities for helping responsible decision making in an increasingly complex world. But as Forrester (2007) sighed, the system dynamics community is not yet making the change for policy making it should aim at. One possible cause is that many system dynamicists are specialists in the SD method and generalists as regards to the themes involved. As a result, there are few position papers collecting the system dynamics insights of all relevant studies in one particular area of application. The purpose of this paper is providing such an overview of system dynamics works on recent dynamics in global real estate markets.
The article sets out to describe the first stages of conceptualization process initiated within the scope of an action research project in the field of waste and residual resource management in a large urban center in a low-income country. For the project it is important to test that the technological concepts developed by the project have the potential of improving waste management in future megacities. This involves evaluating if when implemented, these technological solutions can contribute to the alleviation of the current problematic situation. Additionally, it is important for the project to find out to what extent could the performance (financial, socioeconomic, environmental, etc.) of the waste management system improve as a result from the implementation of the waste management strategies it proposed. For this purpose a set of simulation models is being conceptualized and developed using a modeling methodology (namely System Dynamics), which will allow evaluating how the waste management situation would evolve if a set of strategy options would be introduced. This would be done by comparing the future development of the system in the absence of the strategies (business as usual) with the development of the system in the presence of the strategies. The article presents the first results of model conceptualization and gives an outlook of the activities that will follow.
This paper examines the effectiveness of different delivery methods for teaching System Dynamics to undergraduate engineering students. The paper presents the findings from a survey of the learning styles of the student population and compares that to the current breakdown of the course content by learning style. It presents the findings of several classroom assessment techniques that were conducted over the course of a semester to evaluate the effectiveness of the delivery methods utilized in the course. The classroom assessment techniques focused on an evaluation of the effectiveness of readings, lectures, labs, and case studies in teaching the material. Additionally, students participated in two self-confidence surveys mid-semester and at the end of the semester, which evaluated their confidence in their ability to accomplish the course objectives and the content delivery methods. Based on this evaluation, the paper presents recommendations for improving the content delivery methods of the course to take advantage of the student populations learning styles.
Ongoing counterinsurgency operations in Iraq present a complex, dynamic environment in which traditional analytical methods struggle to explain the behavior over time. System Dynamics is extremely well suited to analyze this environment as the methodology focuses on understanding the structure of the system and the behavior it creates. This paper proposes a system dynamics model of reconstruction projects for essential services to examine one aspect of this operating environment. One of the many challenges that exist in this environment is determining the proper balance between the use of the Commanders Emergency Response Program (CERP) for small scale and major reconstruction projects. This paper attempts to mitigate this challenge by analyzing the structure of the system, modeling the behavior of the system over time, and proposing policy recommendations to improve the system behavior. Although the model is not calibrated to historical data, it produces behavior consistent with behavior described in Army doctrine. The causal relationships provide valuable insights into the dynamic behavior of reconstruction efforts and their impact on essential services. With further calibration of the model, leaders can develop and evaluate policy alternatives for capacity development to mitigate the impact of the insurgency.
Although both India and New Zealand recognise trade between the two countries as important for their respective economies, the current and past trade in information technology between the two nations has been very low. This research seeks to study this problem situation systemically by analysing the complex interactions of factors responsible for this situation. While most of the literature on IT offshore outsourcing is based on client perspectives, this study takes a service provider perspective. A causal loop model is developed to explain the underlying structure related to this problem situation. Finally, strategies to improve the problem situation are discussed using an analysis of the feedback loops captured in the model.
Unconventional gas has raised debates all over the world following its considerable contribution to the natural gas production of some countries such as the US. The Netherlands, which is a prominent gas producer in the Western Europe, also considers unconventional resources as an alternative to conventional production, which is estimated to significantly decline in the next 25 years. However, the development of unconventional gas in the Netherlands is surrounded by several uncertainties. In addition to parameter uncertainties, uncertainties in the boundaries and structures of the models used in the analysis of this future development play an important role. This study aims to investigate the effects of such uncertainties on the production rate of unconventional gas, by combining the Exploratory Modeling and Analysis method with four different SD models. The results show a wide range of production rate possibilities, where the variety is mostly caused by the model uncertainties. This study can be extended with more model alternatives, and the results of this study can be used in further analysis for robust policy making.
Aggregate continuous time formulations used in System Dynamics models result in the implicit mixing of individual constituents of levels. Normally, this is acceptable as the heterogeneous nature of model variables implies that some individuals counted in a levels value will pass others and exit earlier. In models with a focus on chronological aging and age-related characteristics this phenomenon, which we call cohort blending, can result in large distortions. Though these distortions can be reduced by using aging chains, they persist in a significant way even when using one-year grouping in the aging chains. As an alternative, we introduce an approach we call continuous cohorting in which populations are tracked with cohorts sized the same as the computational interval of the model. This approach eliminates the blending problem with minimal notational and moderate computational burden. The resulting models display quantitative, though limited qualitative, differences from their traditional counterparts and are more easily defensible with demographers and others who study population.
There are increasing environmental concerns in México, as in many other countries, regarding the CO2 emissions tendency, due mainly, to the intensive use of fossil fuel based electric generation. Recently, several laws and amendments have been passed in Mexico with the objective of promoting non-fossil generation technologies, aiming to increase their relative participation in the energy portfolio mix. Although several mid and long term objectives in this regard have been established in Mexico, these would be hard to achieve if the investment capabilities should continue to be directed mainly to fossil fuel thermal technologies, like natural gas on combined cycle plants, and proportionally less, to investment in non-fossil technologies. This article presents and evaluates three scenarios based on a System Dynamics Model, to assess the non-fossil generation capacity investment and timing requirements, in order to achieve both ecological and safety strategic objectives, and at the same time satisfying the electric energy Mexican demand expectations.
Supply chain management supported by digital services is one of the most promising areas of research that have emerged in the last years since it has a tremendous potential to improve both operational and economic performance. In particular, distribution of freight is a field that lends itself to the application of the latest information and communication technologies to enable quick and safe ordering and delivering activities. However, in order to make new smart distribution services desirable for users and profitable for providers, careful feasibility studies are necessary to evaluate possible strategies to make the diffusion time as short as possible and secure adequate profits.
Strategic decision on the execution of national security improvement project is greatly important for the present and future national security. Though, the importance of strategic decision, decision making process has been executed under one-way thinking framework. This research provides a decision-making tool with make-or-buy approach for the national security improvement policy execution methods: foreign purchase and military R&D project, and, via simulation, confirms dynamic change of military capability index respect to change in ratio of foreign purchase and military R&D. Results of research are as follows. If the ratio of military R&D investment is under 38%, military capability index from military R&D investment cant overtake increasing effect from foreign purchases in the whole life cycle, so easy to be restricted by another country. Applying the model from this research provides an appropriate ratio for short term and long term defense strategy and policy goal, and consequent result of increase in national security capability. Thus, this research model can be effectively utilized for national security improvement project.