Foreign direct investment has a strong impact on the level of employment and its structure in companies. The article presents the structure of factors regulating and adjusting the employment scale to real productivity needs. The presentation is based on one of the best examples of foreign direct investment in Poland - GlaxoSmithKline Pharmaceuticals, Joint Stock company. The privatization process is like a mirror of destabilized economy. The correction of employment structure inside the company reflects the overall employment fluctuation in economy and even the structural unemployment classification. The model built on the GSK example, describes the 8 years long process of employment adjustment and can be recognized as a benchmark for the employment transition in foreign companies in Poland.
Our objective is to examine the consequences of soy rust to the U.S. agriculture in the next 2-5 years. In 2000, the U.S. harvested approximately 2.8 billion bushels of soybeans from almost 73 million acres of cropland, accounting for more than 50 percent of the world's production. The crop generated $12.5 billion dollars, $6.66 billion in exports. Soy rust established itself in the south last November and is expected to disseminate and deposit in the crops during this years planting season. The extent of outbreaks depends upon climatic conditions. Early detection is crucial since soy rust is deadly to the soy plant within 48 hours. Monitoring systems will warn farmers of the presence of the spores and farmers are instructed on how to identify and treat it. There is uncertainty regarding the sufficient and timely availability of fungicide. In addition to historical data, we incorporate observations of on going planting and harvesting. Parameter ranges in the model are narrowed as more information becomes available and existing uncertainties dissipate. The impact of soy rust is analyzed in aggregate, looking at overall production and market share contrasted against natural noise in the yields.
Traditional global models address important global problems using highly aggregated measures, but it may be argued that the world is strongly non-homogeneous at least at some fundamental level: developing (South) nations and developed (North) nations may have very different, asymmetric problems, goals and structures. This study aims to investigate these two distinct groups of economies in a context of global sustainability. We identified population, economic growth, welfare gap, energy supply and pollution as key issues and analyzed them in a systems perspective. A dynamic feedback model, which discriminates these two groups of nations, is constructed based on WORLD-3 model in order to study the dynamics of key parameters related to these issues for the period 1975-2050. Simulation experiments reveal that population characteristics of South and current mode of economic activity, which is extensively dependent on non-renewable energy resources constitute serious obstacles for the sustainability of the system. Hence, stabilizing the population growth in South, transition to alternative energy resources and investment support to South for this transition are vital for closing the welfare gap between blocks and sustaining the global system.
Effects-based Operations (EBO) is becoming the centerpiece of Western military thinking. The concept is based on influencing the behavior of adversary complex adaptive systems (such as terrorist networks) in dynamic environments. Mission analysis is the foundation of campaign planning. This paper suggests a process to improve how campaign planners identify effects necessary to yield a desired endstate during EBO mission analysis. The process is based on using a modified version of Soft Systems Methodology to structure the problem by providing planners a high-level initial understanding of the dynamic complexity associated with 4th Generation Warfare threats. Planners use this understanding to identify and diagnose specific adversary behavior inconsistent with the directed endstate. Potential system changes to modify problematic behavior are next identified and debated. Finally, the changes are converted into effects that serve as the input into more detailed planning efforts. The process uses group learning and shared understanding as a hedge against the ambiguity associated with 21st Century military planning.
In this paper, the typical anchor (expected value of the outflow or expected loss) used in the most popular decision rule of the stock management modeling, the Anchoring and Adjustment Rule is studied for structures including a decaying stock. A new anchor (equilibrium value of loss) is proposed and compared with the expected loss formulation. We demonstrate that equilibrium value of loss formulation helps bringing the control stock to its desired level more rapidly. In addition, we show that managing a decaying stock in a stable way is difficult when the supply line is discrete. Standard stock adjustment and supply line adjustment terms anchored around expected loss can yield highly unstable oscillations. Counter-intuitively, for some cases, ignoring the supply line adjustment term may completely eliminate unwanted oscillations. If equilibrium value of loss is selected as the anchor and when the decay time (life time) is small enough, management of the stock can even be done by ignoring all the adjustment terms.
This is a second paper of a series of macroeconomic modeling
that tries to model macroeconomic dynamics such as the determination of GDP (Gross
Domestic Product) and money supply from system dynamics perspective.
Following the first paper on the money supply and creation of deposits,
this second paper tries to model dynamic determination processes of
GDP, interest rate and price level on the same basis of the principle of
accounting system dynamics developed by the author.
For this purpose, a simple Keynesian multiplier model is constructed
as a base model to examine a dynamic determination process of GDP.
It is then expanded to incorporate the interest rate, whose
introduction enables the analysis of aggregate demand equilibria
as well as transactions of savings and deposits, and
government debt and securities.
Finally, a flexible price is introduced to adjust an interplay between
aggregate demand equilibrium and full capacity output level.
A somewhat surprise result of business cycle is observed from
the analysis.
This paper develops a hypothesis that the normal mode of operation for many organisations is well beyond their safe design capacity and that many health and social care organisations in the UK are in this position. This situation arises from having to cope with demand, irrespective of their supply capability.
The irony is that such organisations can appear to cope at the strategic level. This is because operational managers employ a variety of well-intended, informal, survival techniques to meet performance targets. However, such practices can perpetually mask the underlying reality and have serious unintended consequences .
Evidence for the hypothesis has emerged from a number of studies carried out using system dynamics to identify and promote systemic practice in local health communities in the UK. The rigour of quantitative simulation model construction has identified mismatches between how managers claim their organisations work and the observed data and behaviour. The discrepancies can only be explained by surfacing informal coping strategies. Indeed, the data itself becomes questionable as it reflects more the actions of managers than the true characteristics of patient pathways.
If proved wholly or even partially correct there are some important messages in the paper for Health and Social Care management, the meaning of data and for modelling.
Real-world policy analyses efforts indicate repeated behavioral patterns that inhibit systems approaches, such as the time and budget pressures, the trade-off of detail vs. high-level insights, and the tendency to dwell in the familiar rather than delve into the unrevealed. Examining mainstream (non System Dynamic) business and policy processes issues such as these seems critical to increasing the introduction of systems approaches. However, the perspective we as a community of modelers takes is critical to reinventing business and policy analyses. To the extent the barriers are seen as circumstances of the modeling environments there is little leverage towards resolution; if we can see the impediments as being a result of our behavior as analysts, the nature of the barriers change and there is much more opportunity for improvement. The paper examines a nonSystem Dynamics policy analysis for the electric utility industry from both these points of view.
The two most important fundamental needs of towns and cities are a sufficient supply of adequate drinking water and the removal of polluted water. History has shown that if these needs cannot be met, cities rapidly become uninhabitable. New Zealand's current water systems were designed and built in the 19th century and have not been improved much since. Generally, infrastructure has been built on the assumptions of abundant water resources and the unlimited ability to treat and dispose of polluted waters. Especially in Auckland, New Zealand's largest city and one of the most rapidly urbanising cities in the world, there is increasing tension due to rapid urban growth and the costs associated with replacing old water infrastructure and extending it to new urbanised areas. The challenges of managing urban water systems in New Zealand today call for an application of system dynamics. Our proposed research is based on the hypothesis that systems thinking and modelling methodology can be applied to the question of urban development in the Auckland region and is a valid instrument to identify policies that effectively foster the sustainable development of urban structures, in particular urban water infrastructure. This paper discusses the current situation and challenges, and outlines the proposed research.
The objective of this workshop is to provide participants an introduction to agent-based modeling of
crowd dynamics. A summary of pedestrian socio-psychological egress behavior will be presented
together with an outline of existing modeling techniques and software tools. A detailed description of a
simple crowd model that can be implemented using MATLAB will be presented. Participants will learn
how to develop a simple yet fully functional simulation and visualization of crowd dynamics. Skeleton
Matlab scripts will be available for download from www.sanithw.org starting July 1st, 2005 but will also
be available via PC/MAC compatible USB drives during the workshop.
In a constantly changing environment, a Computer Security Incident Response Team (CSIRT) has to evolve over time in order to sustain or improve its effectiveness. The main task of a CSIRT is to help victims mitigate the effects of computer security incidents. A frequently identified problem for a CSIRT is that they are overworked, understaffed and under funded. In this paper, we present a conceptual model of such conditions based on a case study. The model is a first attempt to understand the main factors influencing a CSIRTs ability to handle computer security incidents effectively, and to identify ways to improve their overall effectiveness. Based on theory from process improvement and information from the case study, we have identified that short-term pressure from a growing incident workload prevents any attempts for developing more response capability long-term. Fundamental solutions to solve this problem will typically involve a worse-before-better trade-off for management.
Information revolutions change the world by taping into a positive feedback loop. If we can identify the loops we can understand where they might be going and what their limits might be. We need to know the difference between a short-term trend and a long term dynamic. We need to know where this information might be pushing us so we can know if it is where we want to go.
Trying to look at a category, as broad as information revolutions, to identify patterns requires an approach that will give a broad but well specified picture a way to understand the positive feedback loops that create the growth and also to understand the countervailing loops that come into play in various ways. I believe that causal loop diagrams can give us a clearer picture of this kind of broad, messy problem
This paper describes transform approaches to control Vendor-Managed Inventory (VMI). The effect of different modelling techniques and their significance is examined. Modelling was achieved with the Simulink package using the equations developed by Disney and Towill for a VMI system model. Analysis of several types of delay representation were compared to illustrate how the results depend on their formulation. The effect of using a discrete model is to deepen the stock-out and increase the required order rate. Analysis of the stability of the different models are discussed and evaluated. It is shown that the continuous model with an exponential delay is always stable and with a fixed delay can be made stable. The requirement for the system is also computed for a discrete model with exponential delay. Reduced inventory stock-out and a smaller WIP peak are achieved with different order smoothing function. This has special significance for e-manufacture.
An interactive learning environment (ILE) appropriate for intermediate macroeconomics students has
been simplified for students in introductory college and high school courses. Without changing the
underlying model or the simulation options, the simplified instructional approach relies on feedback
loop diagramming more than stock-and-flow diagramming. Interactive Vensim causal loop diagrams
are embedded in a STELLA interface, using slide show and video software. In addition, students appear
to learn more as model-users if they engage in preliminary model-building activities using simple
word-and-arrow diagrams.
Diffusion models of radical technologies are often based on an epidemic structure developed on the Bass principles of generic external and internal communications. However, in most cases such processes involve more complex communication and decision mechanisms. The diffusion processes should account for interdependences with other innovations and also the substitution mechanisms with regard to the technology in place. Substitution must be understood with a much broader scope than the analytical view of the Fisher and Pry model. As many diffusion authors have acknowledged (but partially excluded from their models), diffusion is a social process with innovation moving through interpersonal networks. We propose a model that accounts for the dynamics of social factors in technological substitution. Based on the System Dynamics methodology, our model disaggregates most of the communication structure and individuals characteristics that are implicitly embedded in traditional diffusion models. Our discussion starts with the characteristics of radical technological innovations. We then proceed with the theoretical basis of our social aggregation approach by presenting Kellys personal constructs system theory, outlines of social psychology, decision making under uncertainty, and the interdependences between innovations characteristics and human behavior. We also make an attempt at considering both sides (consumers adoption / competitors imitation) of a substitutive diffusion. Brice Dattée's research is funded by the National Institute of Technology Management in Ireland.
This work captures and analyzes the fundamental dynamics of innovative industries with a System Dynamics model. We selectively reviewed the innovation literature, identified the dynamics to be modelled, formulated a conceptual model of these dynamics, and then developed the initial simulation model. By design the conceptual model is simple and generic. It is intended to apply to a broad range of products and services assembled and process-based, complex and simple, physical and digital, business and consumer, early stage and mature, 19th century and 21st century. That is what we mean by the fundamental dynamics of innovative industries. In many variations and combinations they can explain the evolution of most markets. The initial simulation model was developed from the conceptual model. It represents products based on two generations of technology. At this stage the simulation model does not represent a specific market or industry. It is quantified with hypothetical inputs, parameters, and cause/effect relationships. The simulation model recreates well-documented reference modes of market evolution. We currently are building the information base which will enable the initial model to be applied to the photography and display markets.
The, for economists well-known Goodwin model was one of the first models which tried to combine cyclical behavior and economic growth. The basis for this is the predator-prey model a basic structure for every System Dynamicists. The economic literature about the Goodwin model is enormous, but so far, it was mostly concentrate on the mathematical behavior or on some extensions that could be implemented. In addition, there are only two papers from R. Solow and D. Harvie about an econometrical verification of the model and none from a System Dynamics perspective. This article provides therefore two System Dynamics models of Goodwins theory and tests the enhanced one on the German economic situation and on the data provide by Harvie 2000. Additionally there are some suggested modifications of the Goodwin model, tested from different authors, which reveal surprising outcomes for the understanding of Goodwins theory.
In this paper, I will present relatively simple system dynamics models which capture some of the insights of a key critic of the U.S. policy for defending the country, Stephen Flynn. Flynn is especially concerned with the over-reaction to the attacks of September 11, 2001. He warns of the dangers of shutting down legitimate commerce and investing in overseas offensive measures as a knee-jerk reaction to the attacks. It is not that he is advocating a lax approach to security. Rather he is advocating a measured look at the implications of a draconian defense policy which may cause much more damage to our societal infrastructures than the attacks that triggered it. He also presents recommended solutions.
In the modern era, the advances in information technology have been dramatically shaping the ways people live as well as the ways organizations manage their businesses in their professional business domains. Implementing various kinds of information systems, such as Decision Support Systems, has been recognized as one of the most crucial tasks for organizations in order to continue to be competitive or even to survive. Although considerable effort has been devoted to improving the performance of information system implementations, organizations are still constantly suffering from the failures of information system implementations. In this study an extensive framework that depicts the context of information system implementation is developed. A system dynamics approach is used to investigate the dynamic nature of information system implementations. By using the proposed system dynamics model, we contend, executives and information system professionals of organizations can gain comprehensive insights into organizational behaviors and substantial policy-making implications regarding information system implementations.
The pattern of one-shot growth is most seen in software industry. The purpose of this paper is to understand the growth dynamics of a software house and to facilitate the software house to manage its growth. This paper models a major domestic ERP software house in Taiwan that is experiencing the one-shot growth process. Business type-level packages and high quality service is the companys secrets for its success. With a good reputation for high quality systems and services, the companys growth strategy is to expand the market it serves by developing new kinds of packages for more business types. However, how to balance the human resources requirements of R&D and ERP is rather difficult when long delays exist everywhere in a software house. With the system dynamics model built, this paper identifies the archetype of limits to growth hidden inside the software house and illustrates how the problem is worsened by the companys intuitive reactions.
A discussion, with panelists representing different perspectives, facilitated to encourage full participation by everyone present. The field of inquiry dubbed environmental dynamics (ED) includes a broad range of interests, many with differing views of the ecological world. These include, for example, purely ecological studies involving the interactions of organisms and their natural environment, technical studies of the effects of human activities on the environment and different methods employed to limit or counteract those effects, big picture analysis of the human-influenced world and the direction it is headed, plus many others. Popular topics often associated with ED include: environmental regulation, the ecocosm dilemma, the oil crisis, global warming, environmental limits [to growth], etc. The roundtable will explore the relationships among these different topics, emphasizing the role of system dynamics. The goals will be to establish common ground, to create useful distinctions, and to help organize the ED endeavor.
In order to determine whether model testing is as useful as suggested by modeling experts, the full battery of model tests recommended by Forrester, Senge, Sterman, and others was applied retrospectively to a complex previously-published system dynamics model. The time required to carry out each type of test was captured, and the benefits that resulted from applying each test was determined subjectively. The resulting benefit to cost ratios are reported. These ratios suggest that rather than focusing primarily on sensitivity testing, modelers should consider other types of model tests such as extreme condition tests and family member tests. The study also finds that all of the different kinds of tests were either moderately useful or very useful--fully supporting the recommendations of the experts. An interesting diagram called a "tornado diagram" is used to portray the results of the sensitivity testing.
The tourism industry is considered a very important factor that contributes to the economic development Egypt. The industry has shown growth in the recent years in the number of tourist arrivals to reach a maximum of 6 million in 2003. It could not be denied that government efforts contributed to the growth but nevertheless the devaluation of the pound had a significant influence on the number of visitors. The performance of the industry might look fine in general. But, this is if compared to previous performance only. However, if an in-depth look is taken it is realized that the Egyptian tourism is performing far below capacity. This paper aims at explaining the way to improve the performance of the Egyptian tourism industry using a system dynamics methodology. This will be done by defining the main factors affecting the industry, then explaining how the whole system works and finally proposing a new modified model and required course of action.
The researchers attempt to visualize the complexity and dynamic behaviour of SME clusters in Egypt throughout the process of transferring a clusters state from static (idle) to dynamic (productive). This research constitutes the second of two complementary phases of a more comprehensive research that tries to quantify the qualitative measures of dynamic clusters through extending the application of the business dynamics tool to simulate the effect of different cluster-based economic development policy scenarios. After developing the mental model and during the conceptualization phase, the researchers highlighted the key-leverage causal loops showing feedback effects and uncovering the hidden cause effect relationships existing between the most important elements such as trust level inside the cluster, competition and the number of supporting industries. After validating the model, the researchers designed the policy analysis runs and undertook different scenario analysis over a time span of 50 years. Scenario analysis included studying the effect of elements such as institutions for collaboration (IFCs) on cooperation; effect of broker efficiency and success stories on trust building; and effect of trust on learning.
Dwindling government resources and demands for increased accountability have challenged nonprofit organizations to meet their primary missions while also creating efficient and effective back-office accounting and information systems. Even though many nonprofits say that accounting and information support systems are mission-critical, they tend to staff these systems weakly and to be less efficient than they could be. The present paper uses a system dynamics model to show how the Limits to Growth and Shifting the Burden systems archetypes help explain this situation. The model runs show that the exercise of leadership is the underlying issuenonprofit managers must challenge organizational cultures and mindsets that act as limiting factors, causing the nonprofits to avoid implementing fundamental solutions to their problems. The paper discusses several action recommendations.
This study reports of an experimental economics analysis of the new proposed Swedish-Norwegian tradable green certificate market (TGC). The green certificate market is a financial instrument to stimulate renewables within the context of liberalized, transnational electricity markets (a kind of market-oriented subsidy scheme). Green certificates are financial assets issued to green producers that can be traded freely. Previous system dynamics studies showed that trading- and investment behaviour were critical factors in analyzing the market dynamics. As a follow-up, this experimental economics study conducted 14 laboratory experiments with about 10 to 20 students per session. A particular feature is that participants handle both short-term trading and long-term investments, which allow us to analyze the interplay between these types of decisions without imposing behavioural assumptions on the model. The laboratory experiment shows that the market is likely to crash, due to the long time delays of supply side adjustment. The study provided new insights concerning agents trading and investment strategies, in particular the performance of various market designs. The mix of trading strategies employed in response to the experiments, are difficult to understand and capture in an SD model.
The paper describes a system dynamics model developed for dynamic analysis of human resource for the agricultural sector in different sources of employment, viz., government, private (including corporate), academic, financial institutes, non-governmental organizations, self employment, and others in India. Besides projecting an overall scenario for continuation of current agricultural education policy and trends, the paper analyses simulated results from the model for the current curriculum with 80:20 proportion of technical to soft skills. The analysis shows that in the coming years the private sector will emerge as a major employer for the graduates of agriculture and allied sciences.
Following several calls for participation in environmental policy, an increasing attention is being dedicated to the development of deliberative platforms for the sustainable governance of our global village. In this paper, we start by adding perspective on the role of participatory modeling within a strong participatory vision for sustainability. We then explore how system dynamics and ecological economics worldviews interlock in promoting participatory modeling approaches to environmental decision-making. Focusing on the synergies between group model-building and mediated modeling, some lessons from two participatory interventions developed in Portugal are extracted. The evaluation of the case studies indicates positive outcomes at the individual and group level, with respect to learning, reaction, commitment, communication and consensus. The outcomes at the organizational level are still more limited. Further research is suggested on the comparison and complementarity between participatory modeling and other deliberative methods.
The planning of investments for the ports of the North Atlantic range (Hamburg, Rotterdam, Antwerp, Le Havre, Goia Tauro) face a strong growth of the market (double over the next 10 years), large economies of scale, congestion in ports and hinterland connections, and strong competition for parts of the European hinterland. Several investment strategies can be followed. The present strategy has resulted in overcapacity. Modeling allows to trace the dynamic impacts from alternative strategies.
Health care in the Netherlands presents a unique mix of governmental and private responsibilities. Costs for long-term care, expensive treatments and uninsurable care for the complete Dutch population are covered by the Exceptional Medical Expenses Act (AWBZ), administered by 32 regional offices. Every health care provider operates under a contract with the regional administration office. Once contracted services are available, insurers are obliged to reimburse providers for these services even if they are not used by clients. In the coming years part of the Dutch health care will be deregulated and several types of care will be offered under market conditions. Whereas costs for care capacity are at present reimbursed by the government, this situation might change in the future. Regional care offices in general have little insight into long-term developments in supply and demand for health care. This paper describes a system dynamics study on demand and supply for a specific type of nursing care, dementia. The model shows how feedback between waiting lists and volume of different types of demand for care, leads to fluctuations in required capacity. The feared overshoot in long term nursing capacity did not materialize in model runs under a range of environmental scenarios.
Modelling the worldwide nuclear reactor park including all supply chain details, i.e. the nuclear fuel cycle, demands for an integrated nuclear energy system model which also includes feedback loops representing physical feedbacks within the system as well as, and most prominently, socio-political feedbacks in the decision-making on the various available deployment pathways for nuclear energy.
Argonne National Laboratory (ANL) started in 2000 with the development of such integrated nuclear energy system models, i.e. DYMOND and more recently DANESS. These models are based on system dynamics modelling used in various industry sectors and allowing to model the full mass-flow chain of time-varying mixes of nuclear reactor plants and associated fuel cycle options. Several other sub-models may then be coupled to the mass-flow kernel to calculate heat loads, economics, life cycle inventory, and several other parameters and feedback decision-making loops important in the assessment of nuclear energy futures.
This paper concerns a project of limited scope to study why innovations in health care often fail to be adopted and how this may be improved. The project consisted of two workshops with participants from different areas of health care. The objective was to identify factors influencing adoption of innovations, relating the factors to each other, and looking for measures to stimulate the adoption of innovations. During the first workshop, possible effects of innovations and prerequisites for adopting innovations were identified and prioritised. This resulted in draft causal loop diagrams. During the second workshop, refined diagrams were used to identify measures for stimulating the adoption of innovations. In addition, a game incorporating the results of the workshops was developed. The main causal mechanisms were translated into the game which can be played by people who work in health care to improve their understanding of some of the dynamics involved.
System dynamics models are being used by more and more businesses to train employees from new hires to veteran managers, communicate strategic change within the company, share mental models between stakeholders and align business perspectives between business units. Advances in computer technologies help this process to a great extent by enabling users to interact with models more effectively and efficiently. This workshop will introduce you to ExTrain(r), one such technology that facilitates the use of simulation models in strategy communication and management training.
The ExTrain(r) is a web-based application platform that serves as a virtual practice field for managers to exercise decision-making power under various business conditions in a risk-free environment. ExTrain(r) applications can be used in individual online simulation sessions or within a facilitated environment with interaction from trainers. Each application is also supported with a facilitation tool that allows trainers to monitor simulation progress, user performance and intervene if necessary.
In this workshop, we will introduce you to the ExTrain(r) platform and its new features from a user perspective. You will also get a chance to learn more about the integration and maintenance of simulation models within ExTrain(r) environment. There will also be a hands-on demonstration of the system where participants will take part in a sample war-game application. Participants will be divided into four teams, each of which will take control of a virtual technology company. Starting on level ground, you will compete for revenue growth while maximizing profit through various business decisions. Facilitation will be provided to help you understand the key business dynamics and formulate your strategy.
This paper describes the process of a combined system dynamics modeling and scenario planning approach. It empirically investigates how envisioning and probing system dynamic modeling has the potential to raise effectiveness of scenario planning for organizational learning and improved decision making. The approach is illustrated by means of a case study that was used to explore the influence of social trends on dynamic interactions between transport behavior and spatial development in Switzerland. In this case study a system dynamics model was developed that served as a communication tool for strategy development and for enhancing goal alignment between different policy sectors at the national level. A qualitative content analysis illustrates how comments from participants of group modeling workshops can be opened up as empirical indicators of stimuli for improved learning. Additionally, it gives empirical evidence that the chosen approach contributes to mitigating four drivers of unexpected decision failure as discriminated by Chermack (2004a): bounded rationality, the tendency to consider only exogenous variables, stickiness and friction of information and knowledge, and mental model with decision premises.
There was an interesting presentation at ISDC 2004 in Oxford. The title was Spatial urban dynamics presented by Peter Sanders and Frank Sanders. They expanded Forresters original urban dynamics model in terms of spatial point of view. While one of us has been studying Geographic Information Systems (GIS) and applying GIS to consumer spatial behavior. Recently we have got some research results, one of which explains how retailers agglomerate in a city, and the other shows one of the method of calculating relative attractiveness of retail areas. In this paper, we make some contribution toward spatial urban dynamics, firstly discussing the importance of the concept of attractiveness in social sciences, secondly showing latest research result on the attractiveness outside of system dynamics field and how to take it into spatial urban dynamics, thirdly making constructive comments on Sanders approach, finally referring to a strong possibility of expanding spatial urban dynamics toward national models and world models.
This paper discusses our project under a three-year research contract with the Japanese Government to gain public acceptance of nuclear facilities in local communities by improving risk communication through a gaming/simulation approach. Evidence suggests that nuclear public education programs are not communicating the critical safety information necessary to eliminate anxiety of people living around nuclear facilities. To most utilities and government, risk communication means persuasion. Based on the findings of our visits to several authorities, municipalities and nuclear facilities in Japan, Sweden, Norway and USA, we built a causal-loop model regarding nuclear risk communication. According to our model, the root cause of the problem is lack of trust, and the leverages are public participation and transparency which can create learner-centered two-way communication environment. THE TREASURE HUNTING, one of our five gaming/simulations for this project, is intended to create such an environment so that local residents may deepen understanding of nuclear risk and build up a mutual trust relationship with disaster prevention experts. After many internal test runs, we have run this exercise six times so far with the nuclear disaster prevention experts and the local residents near nuclear facilities in various parts of Japan. The results have been quite satisfactory.
The focus of this paper is information exploration using alternative utilization models to test how a supply chain responds to demand changes. From the feedback perspective, it is found that the echelon stock policy generates a more complex feedback structure than the installation stock policy; and has different time patterns of inventory adjustment actions. Considering the relative higher cost for small- and medium- size enterprises to adopt advance information technology in our textile supply chain case, this paper further examines the impact of information technology in the echelon stock policy and the installation stock policy. The findings show that information technology investment could be more beneficial for supply chains with the installation stock policy. Finally, this paper mixes the PID controller design concept with the two information utilization models and so suggests further development for information utilization designs.
Organizations are becoming more aware about the importance of economic, financial and risk management aspects of information system security. As a result, the balance between preventive and corrective security strategies must be studied. We understand Preventive Security as the ability of organizations to avoid the impact of an incident and Corrective Security as the ability of the firm to recover from the losses generated by an incident.
This paper presents a model to analyze the Preventive-Corrective security balance. The main objective of this model is to simulate and analyze the impact that two security behaviors (security investments and strategy) can have one a given enterprise environment. After running 54 simulations, some interesting security behaviors called our attention.
System Dynamics does an excellent peer review of articles. This year, eeing the reviewers' comments and suggestions online was especially welcomed feedback. The additional benefit of initiating a dialog with the reviewers was a bonus.
However, there is always room for improvement. Your thoughts and ideas are welcomed to help us continue to improve our peer review process. Please consider joining a dialog at our Boston meeting to further explore the peer review process. Your presence and ideas are welcome.
Some thoughts for consideration are as follows: 1. Need the peer review process start and end so abruptly? Should the reviewer and writer continue the dialog post the society meeting if mutually agreed? Should a reviewer mentor this process? 2. Are there submissions for review that could be enhanced and offered to other venues for publication, and thus improve recognition for the System Dynamics Society? Should a reviewer mentor this process? 3. Could a practitioners develop a business methodology from theory presented in a peer reviewed paper, or could academics proved theoretical underpinnings for a practical approach presented? Should a reviewer facilitate this process?
If you are interested in discussing these peer review ideas or others, please consider joining an informal meeting!
This paper explores Dynamic Unity between Theory U and System Dynamics
as a way to generally illuminate the "blind spot" and create the setting for
presencing. By describing the blind spot as a System Dynamics process with a
model and behavior, it is hoped that Dynamic Unity will facilitate recognition of the blind spot and produce better understanding of social actions. Dynamic unity between Theory U and System Dynamics will facilitate: identification of common assumptions, modeling of the current problem, producing repeatable results through simulation, and discovery of new insights from simulation results. The instance of presencing will remain the domain of social science, neuroscience and others to explain. Using System Dynamics to project policies through simulation, identify emerging phenomenon, accelerate the learning process, decrease dependence on past experience, change mental models into
new insightful beliefs will take us to the threshold of Theory U presencing.
The success of the Polio Eradication Initiative promises to bring the world the benefits of sustained improvements in quality of life (i.e., cases of paralysis and deaths avoided) and saved costs from cessation of vaccination. Obtaining these benefits requires that policy makers manage both the transition from the current massive use of oral polio vaccine (OPV) to a world without OPV and the risks of potential future reintroductions of polioviruses. In 2001, we began a case study on retrospective polio risk management to demonstrate the importance of using a dynamic disease model to correctly estimate the cost-effectiveness of vaccines. Discussions with the CDC about the case study led to an opportunity for us to develop a large model to support the prospective decision making process. This paper tells the story of our journey, emphasizing insights about the requirements for analysts to create tools that really help high-level decision makers.
The development of large software systems using systems dynamics languages has been hampered by the lack of application of, and support for, modern software techniques. Support is needed to handle the challenges of modular system dynamics model development. These development challenges include the handling of namespaces, linking separate modes, and maintaining clean logical separations among components. Most modern software patterns and languages support such a capability. This paper presents an approach to group, large scale, system dynamics model development that has proven valuable in our project. Our approach included the creation of a software tool, called Conductor, to facilitate our group development. The tool, Conductor, is generally applicable to other projects using Vensim®.
Mental models are bases to recognise phenomena and make plans to improve situations. They can be expressed in model builders' natural language. It is also necessary to examine mental models using a computer simulation. The Computer simulation requires expressions, which can be translated into computer codes. Therefore, model builders need to translate their model from their own natural language to simulation-friendly language, i.e. stock flow diagrams in System Dynamics. It is widely recognised that this translation is sometimes difficult not only for people who are beginners of System Dynamics but also for people who are experienced in the field. This paper discusses a possible translation procedure and shows an application of it. The proposed procedure is designed to use a subset of a natural language as an intermediate language. This idea is applicable regardless of variety of natural language.
Today software vendors have various ways to handle their products. In contrast to non-software products, software products' properties can be changed or controlled at a low cost; vendors do not need to extend their operations, and well-designed software can be customized systematically. Moreover, its diffusion is influenced by network externalities. The diffusion structures of software that have single user type, e.g. World Wide Web browsers, can be expressed mainly as a single reinforcing loop. This is because users can be considered as homogeneous. However, there are multiple possibilities of structure, which corresponds to business strategies for software which has divided users. An example in this category would be highly specialized software, e.g. simulation software. We attempt to explain diffusion processes and characteristics concerning network externalities of software in this category using System Dynamics models. This paper shows that multiple editions can more effectively assist diffusion of main products than strengthening network externality effects.
We describe an attempt to model an enterprises expansion into business adjacencies within the scope of a Master thesis. It was crucial to define a strategy that would allow the Master student to grow with the task (gain experience with modeling), at the same time ensuring communication with the client and proving the ability of qualitative SD modeling to deliver insights.
After identifying problem symptoms, the enterprise problem was explored with methods from Chris Zook: Beyond the Core. Six cases from Zooks book offering points of entry for the enterprise problem were cast into generic archetypes and presented to the problem owner. Two archetypes belonging to the Underachievement class were identified as most relevant for the enterprise problem, viz. 1) underachievement due to long distance between the core and the adjacency, and 2) underachievement due to poor adjacency repeatability. We developed a preliminary system dynamics model embedding both archetypes. The model gives sensible results with basic policies affecting distance to the core and repeatability. The preliminary results have strengthened the clients interest in the modeling work. Further joint modeling sessions have been scheduled. Work is still in progress.
Though evaluation of public policy and projects of government-to-government assistance are quite common in Japan, evaluator use logical model bases for evaluation that is simple tree type model without incorporate loop or feed back effects. Author has insisting that SD modeling is applicable for quantitative evaluation of public policy but find some difficulty with traditional group model building method. In this paper, we wish to discuss new style SD/ST model building for public policy evaluation.
Pressures from human induced climate-change, pollution, and fossil fuel scarcity stimulate interest in alternative fuel vehicles, and in particular hydrogen fuel cell vehicles (HFCVs). The transition from internal combustion engine vehicles to HFCVs is complex as various chicken-egg mechanisms interact in a highly integrated fashion, and the mechanisms are highly non-linear. This paper focuses on one of the most critical chicken-egg problems: the mutualistic dynamics of HFCV adoption and its fueling infrastructure. The effects of local demand-supply interactions on these dynamics are explored in depth. This paper develops a dynamic, behavioral model of vehicle adoption and fueling infrastructure with explicit spatial structure. Simulations are performed for a reduced version. A homogeneous market with strategically locating fuel-station entrants yields fast transition through the formation of adoption clusters (niches). However, under heterogeneous conditions the same micro-mechanisms can counteract the emergence of a sustainable market. Policy implications are significant. This spatial behavioral dynamic model (SBDM) can be used to compare targeted entrance strategies for hydrogen fuel supply. Insights can be used for an aggregate HFCV transition model that includes other mechanisms. Finally, the paper should stimulate a discussion on merits and limitations of spatial modeling as applied to more general socio-economic issues.
This paper discusses a model developed to assess the effects of land-use changes on traffic congestion and air quality. The inputs are characteristics of development and the outputs are time in traffic per capita, and tons of carbon monoxide from vehicles. As previously developed urban dynamics models have done, the model includes a relationship between the output variables and the attractiveness of the area as a place to live. Particular attention is paid in this paper to challenges associated with modeling the relationship between population and land development in urban areas where alternative land-uses are being contemplated. The evolution of an approach to overcoming the challenges is presented.
This paper uses the framework proposed by Rouwette et al. (2002) to describe the group model building stage of a project to integrate land use, transportation and air quality planning in a rapidly growing metropolitan area. The purpose of the paper is twofold: to present a case of group model building in the public sector, and to test the framework for reporting about group model building interventions. The main goal of the intervention described is to evaluate the effect of potential land use and transportation policy changes on urban quality of life factors such as air quality and traffic congestion. A secondary goal is to foster interagency and intergovernmental collaboration. After approximately 15 months, the project is at the end of its first stage. A quantitative model has been completed and is being tested by the modeling group. In the next stage, the model will be used by policy-makers for policy evaluation.
This article attempts to build a simulation model of the impacts of factors that facilitates faculty adoption of Web-Based Instruction (WBI) from the perspective of the faculty stages of concerns. Faculty have different concerns as they integrate new technology into their teaching. Without reducing these concerns, WBI integration will not be successful. Four main stages of faculty concern (information, personal, management, and impact concern) were identified based on Halls concern-based adoption model. Reviewing literature on the diffusion of on-line education, we have identified support factors that may decrease facultys concerns for adopting WBI in their education settings. These factors were incorporated into the simulation model in order to test the potential impacts of the factors on faculty adoption of WBI. The current simulation model built in Stella® will aid educators or administrators to evaluate the impact of the factors on adoption of WBI.
The purpose of the paper is to propose a modelling approach to be used in targeted organisational interventions focusing on strategic business objectives and change management. The approach builds upon prevalent participative modelling approaches with the extension of increased focus on intervention planning, stakeholder management, and structured implementation. A single-site longitude case study regarding development of a balanced R&D location strategy served as inspiration for the development of the approach and in the paper it also serves as a practical illustration of the approach. Interesting insights include successful observations of individual learning and group communication in a modelling study, which is more targeted on predefined business objectives than usually seen in the SD community. However, generic conclusions must await further research within the area.
The 5th International Ph.D. Colloquium is an event of the System Dynamics Student Chapter. The objective of the colloquium is to bring together Ph.D. Students working on foundations, techniques, tools, and applications of System Dynamics and give them the opportunity to present and discuss their research in a constructive and international atmosphere. The Colloquium will also provide an opportunity for student participants to interact with established faculty and others in the wider system dynamics community. The diversity and the interactive setting should provide a unique learning opportunity for all participants of the colloquium. This year, the all-day colloquium will open with a speech given by Professor Repenning. The colloquium will consist of number of sessions with oral presentations followed up by parallel workshops, as well as a large poster session in the afternoon. We have received more that 20 submissions and we believe and hope it will be an interesting day with many fruitful discussions.
The paper describes a partnership project between three parties, centred on the use of System Dynamics (SD) in a Mental Health Trust (MHT). The main learning experiences relate to the politics of introducing challenging concepts in a situation where participants prefer to avoid confrontation. The rigorous nature of SD modeling and simulation raises questions which operational managers may fear reflect badly on the organization and their own capabilities. They may be uncomfortable with questions about the evidence-base for current treatments, or the research to back their ideas for future developments. A further issue is the ambiguity inherent in definitions of SD and the likelihood that many managers prefer single-issue projects, based on their comfort zone of practice/expertise. A hypothesis is developed to describe the observed reactions in the project and suggest alternative approaches in carrying out SD projects in the UK public sector.
A variety of approaches are being developed to elicit knowledge from clients and develop that knowledge into conceptual maps and formal simulation models. We completed a project that provides a case example where the standard method was adapted for use in a group model-building intervention. We worked with a group of 10 wildlife managers to support system conceptualization, model formulation, and management response to an increase in negative human-black bear interactions in residential areas of New York State. This article discusses the procedural and conceptual steps, insights, and lessons learned from our model building intervention. Our paper focuses on model-building process and learning outcomes, rather than quantitative validation of a simulation model.
Most large development projects suffer overruns and delays, despite substantial effort spent on systems tracking risks and projecting performance. Managers have an especially difficult time making big decisions such as major project re-plans. Typical project management systems have key blind spots that limit their value for comprehensive decisions. Most project management tools are blind to project dynamics variations in productivity and quality over time under different conditions. System Dynamics models have been used to address this weakness and capture project dynamics, but typically these models have their own blind spots as they omit key details. With many pressing decisions and little time, managers rely on intuition to supplement the limitations of management tools. The combination of little time for major decisions, limited tools, and unreliable intuition is a key contributor to the poor results often achieved on major projects. This paper offers perspective on the challenges of making major decisions and describes a case using an integrated management tool -- a System Dynamics model linked to a database of project details. This management system was used to restructure a multi-billion dollar development program with detail and rigor examining dozens of different options, sensitivities, and leverage points in one month.
Studies made by the Swiss politician Jean Ziegler show that the world agricultural system is able to feed twice the population of the planet. However, 800 million people are hungry. During the last years, the Colombian Government has been designing policies oriented to provide solutions to the hunger problem and thus to decrease the number of Colombian families which lack this fundamental right, the food supply. However, the effects of these policies have not been the expected ones, on the contrary, lower class people is still plunged into poverty and hunger. Why have they not been effective? Which have been the consequences of implementing those policies?
Considering the impact of economic liberalization during the 90s on the agricultural sector, a model has been constructed taking into account the national production, the cultivated area, the people working and the capital invested on the agricultural process. The simulation results of the implementation of the commerce liberalization policies seem to match with the results recorded in the Agricultural and Rural development Ministry. Finally, the model will be tested in a scenario that includes the policies that are part of the Development Plan proposed by the current Government 2002-2006 to observe possible consequences of this implementation.
Effective citizenship for the 21st Century calls for young people adept at understanding a world of growing interdependence and multiculturalism. This means new intellectual foundations for understanding complexity and new learning skills for building shared understanding of complex issues like sustainability. Yet most of our schools remain much as they have long been, with sharply demarked subject matters and public education policies that stiffen these disciplinary identities. The result is that even older students have little mastery of understanding of the critical problems shaping their world. New educational outcomes require new educational systems - not just "school systems" in the traditional bureaucratic use of the word but learning communities within and beyond the school that can affect all aspects of children's lives. Peter will share information and invite conversation around current work to develop a network of innovative school systems pioneering a multi-layer view of curricular, institutional and community innovation.
The strategy to recover components from discarded electrical and electronic equipment to obtain spare parts is promising, especially during the final service phase. In that phase, the original product is no longer produced and the sources of new parts are often limited. Controlling those closed-loop supply chains is challenging. Decision makers have to choose when to acquire discarded equipment, when to recover used parts, and when to produce new parts. We developed a generic system dynamics model that provides a test for various proposed policies to control closed-loop supply chains with parts recovery and spare-parts supply.
In banks decisions are made in a speedy and complex environment often with huge uncertainty. This risk must be managed proactively on an enterprise level. To accomplish this task, a systemic view of the bank is essential. Up to now there is no standardised approach for analysing the overall risk dynamics of a bank that is capable of describing the forces inherent in risk management. Most risk models are constrained by their static view, so that they hardly capture the rapid and discontinuous changes. This paper examines the dynamics by applying system dynamics to enterprisk risk management, with the aim of understanding the banks risk dynamics. In order to simulate the risk dynamics of a universal bank a dynamical enterprise risk model was developed. By combining the disciplines of enterprise risk management and system dynamics, this paper shows how a systemic view can improve structures in bank risk management and the need for large system thinking.
This paper proposes a contribution to the domain of systems thinking skills. Empirical studies have repeatedly shown surprising misperceptions and inabilities in subjects confronted with tasks involving very simple stock and flow systems. Here it is proposed to represent these skills as implicit integration, by which Polanyi modeled our ability to know. In this framework, Dreyfus and Dreyfus five stage model of learning is used to construct three hypotheses concerning the learning of systems thinking and its importance for learning from modeling and interaction with models. The tests elaborated by Ossimitz are adapted for this purpose and some tasks are added, to serve in the experimental corroboration of the hypotheses. Since the empirical work is currently under way, only few results can be presented; consequently the main contribution is the conceptual construction of the hypotheses.
The aim of the System Dynamics Model KEYNEO is to model the German economy over a long time period (40 years). Keynesian and neoclassical elements form the base of KEYNEO. In the first step a complex feedback structure was developed to model the main economic variables on an aggregate level. The equations for the supply and the demand side of the economy were defined in the second step.
The results of different runs demonstrate that KEYNEO mimics historic data quite good. With the use of optimization tools the parameters could be estimated. The statistical analysis of KEYNEO shows that the results are highly significant. This verification underlines the quality of KEYNEO to model an economy.
In addition, the structure of KEYNEO may serve as input for much more sophisticated models.
The aim of the System Dynamics Model ESCOT is to describe a path towards a sustainable transport system in Germany and to assess its economic impacts. ESCOT was developed within the environmentally sustainable transport (EST) project of the OECD that was designed to set-up the ecological and technical framework of a transition towards sustainable transportation. ESCOT comprises five models: the macroeconomic, the transport, the regional economic, the environmental and the policy model.
The economic assessment for environmentally sustainable scenarios shows that the departure from car- and road freight-oriented transport policy is far away from leading to an economic breakdown. By expanding the time period for the transition we derived even more encouraging economic results.
For the economic assessment it is important that ESCOT considers not only first round effects but also secondary effects. This ability makes ESCOT a powerful instrument for the assessment of such large system changes.
A system dynamics (SD) model without an instructional overlay is not a sufficient learning tool (Spector and Davidsen 1997, Alessi 2000). We propose Cognitive Load Theory (CLT, Sweller 1988) as a theoretical framework for devising effective instructional context for SD models. Providing a systematic distinction between the several sources of cognitive load, CLT specifies what (and why) should be considered when the instructional overlay for a learning environment is designed. Having developed a simple SD model of the theory, we use it to explore how various instructional choices might impact effectiveness of the learning process. Finally, we consider the CLT recommendations in the context of SD-based learning environments and discuss how they may provide input to developing a set of guidelines for design of effective ways to communicate insights of SD models to a broader audience.
CSIRTs are security incident handling organizations serving a parent organization or a constituency of independent organizations. CSIRTs struggle coping with the increasing number and sophistication of incidents; staff is overloaded with work; managers 'over-utilize' their teams. The CSIRT 'mismanagement' problem can be framed as a case of natural resource management. Studies by Moxnes suggest that misperception of dynamics may contribute to natural resources mismanagement. We replicate experiments by Moxnes (2004), reframing the one-stock reindeer rangeland management task as a challenge in sustainable CSIRT management. Our results suggest: 1) The misperception of dynamics persists when the problem context changes; 2) people employ a simplistic anchoring-and-adjustment decision rule to deal with the problem; 3) our data do not support the version of the rule proposed by Moxnes. We hypothesize that the observed misperception might at least in part depend on the way in which the task was presented.
Information Systems are a key factor for firms competitiveness. Thus, their efficient management has become a key concern and security management one of the most relevant issues. An empirical study has been developed to determine the characteristics of security management within Small and Medium sized Enterprises (SMEs). A summary of the main data from this study is presented.
The results of this study have showed that the evolution of security management within firms has evolved through similar patterns of behaviour. Some phases have been defined to explain the evolution of security management within SMEs. The defined phases are: Growth, Integration, Formalization and Involvement. To explain these phases causal loop diagrams and behaviour over time graphs have been used. Both elements help to more accurately understand the mental models of the people in charge of managing the security of information systems.
The implementation of an ERP (Enterprise Resource Planning) demands the development of a complex project. On one hand, the scientific literature presents some key factors which allow the project to reach the expected objectives. However, these researches do not consider the dynamic relationships that take place among these key factors, although interrelations can benefit or stop the project development. On the other hand, there are different useful strategies for an ERP implementation that directly affect the project development. This paper develops a generic model to identify the relationships among the main key factors (best fit with current business process, resistance to change and training). The model has been validated by a company dedicated to ERP implementation in Spain. Finally, the model will also be useful to analyze the impact of the different strategies in the management of an ERP implementation project according with the project cost study.
The quest for the right E-Learning business model is a strategic issue for E-Learning-companies management. But like any new concept, it is not short of confusion and ambiguity. This article gives a short review of the controversial discussion of the value of E-Learning business models and presents a simulation model built on system dynamics concepts to analyse and evaluate formalized E-Learning business models. This simulation model has been initialized and validated by empirical data gathered from literature research and five structured expert interviews. The simulation for different pricing and licensing scenarios for E-Learning products reveals the complex feedback structures in the pricing setting process and their impacts on the performance of a E-Learning content provider.
This paper has two goals: The first is to present a computerized version of Beer Game originally developed as a board game to teach managers the principles of supply chain management. The multiplayer interactive simulation game we develop is 100 percent faithful to the original game, so that experimental results from the physical and computerized environments can be safely compared. The simulation model used to represent the game also illustrates some subtleties that a model builder must be careful about while simulating a discrete and physical game. Secondly, the game was used as an experimental platform and experiments were done in order to analyze game medium (computer vs. board), demand pattern and learning effects on performances of players. One striking result is the fact that subjects who played the board game scored significantly better than those who played the computerized version under the same conditions.
This paper analyzes the design and functionality of the nuclear reactor, and the human failures on on-line operations, which had led to the accident at the Chernobyl power plant, In April 26, 1986. The paper finds that the combination of the Chernobyl-reactor characteristics and freak infringements of safety rules did cause the accident. The former aspect is due to the process of graphite-moderated uranium fission, which tends to increase in reactivity in the case of a malfunction or faulty operation. The latter is caused by the effect that infringements which did not cause accidents in the past lead to more violation of safety rules in the future. Transferred to organizational improvement programs, a corporation has to redesign its structure in the vein that failures cannot spread quickly (i.e. loosely coupled system elements), and to generate an atmosphere in order to encourage and utilize the full benefits of employees participation.
In this paper, we develop a comprehensive eigenvalue analysis for linear models, in order to identify the leverage points in models. The analysis is comprehensive as we develop a closed-form analytic function relating the behavior of any state variable to all parameters in the model. Moreover, by decomposing the behavior into several modes of behavior each characterized by an eigenvalue and an eigenvector it is possible to develop a closed-form analytic function relating a certain mode of behavior to all parameters in the model. In the first section of this paper, we explain the mathematical foundation of eigenvalue analysis. In the second section we identify the origin of the modes of behavior. This enables us to pinpoint the leverage points of the model. Finally, in the last section, for illustration purpose, we apply the method to a linearized version of the classical market growth model. The analysis of this linearized model enables us to explain the model behavior as a superposition of a number of behavior modes, and set the stage for analyzing the original, non-linear version of the model.
Neoclassical economics seems to have rejected the concept of limits to growth by assuming that the market and the technological advances invoked by it will make it possible to tap new resources and create substitution of production factors, while it has outright excluded limitations invoked by the political, psychological and social institutions in its analysis. Classical economics, other the other hand, appears to have been cognizant of a multitude of limitations to growth, including demographic, environmental, and social. This paper reconstructs classical economic growth models using system dynamics method and demonstrates their behavior using computer simulation. A case is made for taking a pluralistic view of the growth process and reincorporating a multitude of institutions driving it into our models to arrive at realistic policy options.
This paper defines a hypothetical Law (HL) of capital accumulation that includes a growth rate of supply of labour force as a non-linear function of capital intensity. The main state variables are the labour productivity, relative wage, employment ratio, and capital-output ratio. An application of an extended Kalman filtering to the US macroeconomic data 19692002 exhibits long wave as a viable pattern generated by capital accumulation.
Applying the Structural Control Theory the present paper reveals closed loop control over a fractional growth rate of total profit and its advantages in comparison with an open loop control. The supposed control law of primary distribution of income for the macroeconomic oscillatory system is derived as a substantial modification of the initial HL.
It is shown that the US state and business leadership has been pursuing pro-growth stabilization policy with a focus on primary income distribution at least since 2001.
India is emerging as one of the biggest markets for offshore services. Business process outsourcing (BPO) is the delegation of one or more information technology (IT) intensive business processes to an external provider that, in turn, owns, administrates and manages the selected processes based upon defined and measurable performance metrics. Offshore outsourcing is an umbrella term covering a range of IT and business services delivered to companies in developed countries by personnel based in developing countries. Though Indian outsourcing industry is growing, the attrition rate is also rising in this sector. So is the backlash against outsourcing. In order to survive and grow in this scenario, Indian firms must ensure that their services are not only cost-effective but also qualitatively superior. The present study probes into these issues. The study aims to explore the structure of Indian outsourcing industry through the methodology of system dynamics. A system dynamics model has been developed, validated and simulated over time to understand the trends that characterize this industrial segment. The implications of the results of the study are discussed.
This paper is aimed at formalizing an objective method to analyze and assess operational risk in supply chains. The proposed approach consists of exploiting the analogy among logistic networks and dynamical systems; in particular, it proposes to identify the risky events characterizing a generic supply chain by studying its attributed Petri net and the corresponding coverability graph, whereas it suggests to assess the risky events effects by building the logistic network simulation model, experimenting on it and applying ANOVA to the experimental campaigns results. Finally, the method has been applied to a single-item, 3-stages supply chain to show how it can be practically used.
Firms need to act entrepreneurially to compete in today ultra-competitive business environment. This requires firms to actively search for and exploit opportunities to increase revenues or decrease costs in an uncertain environment. Within a firm, these activities are the functions of the entrepreneur or the entrepreneurial resources. In return for their services, these resources receive payments known as entrepreneurial rents. These rents are the result of subjective judgments and the activities that generate them are subject to imitation. Thus, entrepreneurial rents are both ex ante non-contractible and temporary. These characteristics make their measurement difficult for managers. This paper is an attempt to measure entrepreneurial rents using a system dynamics framework. System dynamics models are uniquely positioned to capture the dynamic complexities of these rents. In doing so, I present a SD model of a three-site hog production operation and compute the entrepreneurial rents generated from several arbitrage and innovation activities.
This paper focuses on the application of system dynamics in the integration of knowledge management (KM) and human resource management (HRM) with specific reference to the determination of the optimum setting of time-based policy parameters. The integration of KM and HRM is w.r.t. the engineering competence pool development and deployment. The feedback as well as feed-forward loops were used in the development of the control loops, which govern the simulation carried out in two distinct stages. In both the stages, the influence of the governing time-based policy parameters has been studied to investigate the critical parameters, which significantly influence the effectiveness of the system. The simulation results envisage the effect of the policy parameters, based on which implications are drawn for better policy evaluation and control. Even though the study has a national context, the procedure adopted in this research has the potential to be extended to the global level.
System dynamics concepts and methods are rarely referenced in the field of coastal resources management, even though coastal systems and decision-making are dynamically complex and the SD literature offers a rich and relevant body of theory, practice and models. Recent work in the theory of ecosystem management calls for the use of modeling and is becoming of increasing interest to coastal managers. A simple stock and flow model of coastal management is presented that is drawn from the legislative design of one of the oldest and certainly successful U.S. state programs, Rhode Islands Coastal Resources Management Program. This model exhibits several dynamic behaviors intuitively familiar to coastal managers. Model runs are presented using parameters taken from the Rhode Island case, including runs with and without the coastal management program in place. These results are compared with performance data from the 35 year Rhode Island coastal programs permit data base, and closely reproduce long term trends in key variables. The forward-looking scenarios are utilized to suggest approaches for the state program as it enters the new century. Implications for newly emerging coastal programs in developing countries are also drawn.
The growing reliance on technological infrastructures has made organizations increasingly vulnerable to threats from erstwhile trusted employees and clients. Recent research indicates that successful defense from these threats depends on both technical and behavioral solutions. In this paper, we report on our work to identify seemingly reasonable organizational actions that may inadvertently lead to increased risk exposure. We also consider how potential internal attackers may be encouraged or discouraged by monitoring the organizational responses to probes of the firms security systems.
Two interwoven work products are presented: A case study that presents a particular type of insider threat long-term fraud and a simulation model that supports the case, the underlying dynamic theory, and examination of policy options. The case and model combine to produce a motivating and useful exercise that illustrates the problems of insider cyber-threats. This material has been used in teaching of insider threat issues with satisfactory results.
The December 4th, 2004 issue of The Economist had a 3-page Special Report
entitled The future of the dollar which cites the following from the Roubini-Setser (R-S) paper ; if the real trade-weighted value of the dollar remains close to its average in 1990-2003 ( slightly above current levels ) and there is no change in domestic policy, Americas current-account deficit would rise to 8% of GDP in 2008 and its net debt would increase to over 50% of GDP. This projection came from one of three scenario simulations ( their Baseline scenario ) based on a model described in the R-S paper. The R-S papers model, when replicated in Vensim, contains one positive feedback loop to represent how interest on debt leads to exponential debt growth but excludes much of the of the papers rich mental models which imply much more endogenous model structure than that used in the papers scenario simulation model. This SD conference paper recreates the R-S scenario simulation model and then presents another version which tries to include more endogenous model structure based on the R-S papers own rich discussion and mental models.
Telecommunications in developing countries lack adequate planning and policies, so their telephone densities show the lowest values worldwide. The failure in considering the complexity of the regional telecommunication system in developing policies and technological strategies has increased the telecom gap between other regions and this particular sector of the world. We used a system dynamics modeling approach as a methodology that deals with the complexity of the system in order to evaluate existing value added services and access technologies in telecommunications that could accelerate the dispersion of regional telephone services in developing countries. The role of wireless systems, which have a low deployment delay, was found to be crucial in the growth of urban and rural telecom infrastructure in developing countries. The value added services were found to have a positive impact by increasing the financial resources of the telecom company and the number of urban telephone lines.
A novel archetype, abstracted from published work and supported by anecdotal analogies is proposed. Its novelty is evidenced by a comparison with the 'Relative Control' archetype from Wolstenholme's classification. The significant difference is the erasure of the system boundary from 'Relative Control'. The effect is to bring the dynamics entirely within the system thereby creating a 'political' archetype: a structure internalizing the struggle between two opposed policies.
How can we build dynamic models to effectively inform our research? The System Dynamics method offers established practices and principles to enable us to do so. This boot camp is directed to expose PhD students to the (iterative) SD modeling process.
The workshop consists of two parts. In the first part participants will engage in the process of model building from a case and getting some basic insights. Issues that will be discussed include problem definition, model boundary, scope/level of aggregation, generating insights from modeling, as well as challenging the research question.
The second part of the boot camp will address actual issues from participants research based on the important themes discussed in the first section. For this we ask participants to submit a one/two page summary of their current research, comprising: abstract, research questions, motivation for model and two or three main issues. We encourage submitting models in whatever stage of progress. The summaries should be in at latest on Monday of the conference (though earlier is strongly suggested!). The case material will be available upfront so that the participants read the case before hand.
Note: this workshop does not involve one-on-one coaching that the modeling assistance workshop offers, nor has it the conference setup of the PhD colloquium. These sessions are complementary to each other and participants are encouraged to participate in all of them.
Product development (PD) is a crucial capability for firms in competitive markets. Building on case studies of software development constructed from fieldwork at a large firm, this paper explores the interaction among the different stages of the PD process, the underlying architecture of the product, and the products in the field. The study corroborates the dynamics of tipping into firefighting (Repenning 2001) that follows quality-productivity tradeoffs under pressure. Moreover, we introduce the concept of the adaptation trap, where intendedly functional adaptation of workload can overload the PD organization and force it into firefighting because there is a delay in seeing the additional resource need from the field and underlying code-base. Finally, the study highlights the importance of architecture and underlying product-base in platform-based product development, through their impact on quality of new models under development, as well as resource requirements for bug-fixing. Put together, these dynamics elucidate some of the reasons why PD capability is hard to build and how it erodes. Consequently, we offer hypotheses on the characteristics of the PD process that increase its strategic significance and discuss some practical challenges in the face of these dynamics.