This paper presents a small exploratory System Dynamics model related to the dynamics of the 2009 flu pandemic, also known as the Mexican flu, swine flu, or A(H1N1)v. The model was developed in May 2009 in order to quickly foster understanding about the possible dynamics of this new flu variant and to perform rough-cut policy explorations. Later, the model was also used to further develop and illustrate the use of Exploratory System Dynamics models as scenario generators for Exploratory Modelling and Analysis.
This follow-up paper presents several new 'hot' cases for teaching and testing System Dynamics. The cases were developed between April 2009 and January 2010 for the Introductory System Dynamics course at Delft University of Technology in the Netherlands. These cases can be used for teaching and testing introductory and intermediate System Dynamics courses at university level as well as for self study.
The Latinamerican Chapter has the mission to help the SD-community grow in the Spanish speaking countries. Founded in 2003, it has Latinamerican members from Mexico to Chile, from Spain and a growing number of Spanish speakers living in other countries. Since 2003, the annual meeting allows practitioners to gather and newcomers to get in to touch; we have been in Mexico, Chile, Colombia and Argentina so far. These conferences are the base of our positive feedback loop: each year the number of works submitted and presented is increased. Since 2005, the Spanish Revista de Dinámica de Sistemas publishes two numbers per year. The sisTEMAS newsletter and a mail list allow keeping in touch. In November 2009, the 7th Latinamerican Conference took place in Santa Marta, Colombia, organized by Industrial University of Santander, National University of Colombia and University of Magdalena. This year's meeting will take place in Lima, Perú in November 2010. It is an opportunity to welcome new members. If you would like to join us please contact Gloria Pérez ( gloria.perez@itesm.mx), Isaac Dyner ( idyner@unalmed.edu.co) or Martin Schaffernicht ( martin@utalca.cl). The annual business meeting was held in Seoul and affords the opportunity to get involve with the Latin-American Chapter activities and develop the networking we need to develop the System Dynamics field in our countries.
The SDS Education SIG continues to pursue its twin interests in publicising and enhancing both the contribution of SD to Education Management and the evolution of the contribution of SD to the curriculum - in both cases the interest spans the whole span of education from K-12 to Higher Education. This years roundtable/annual business meeting is the place to come to discuss substantive education issues, whether you are part of the Education SIG or simply exploring possibilities. The Ed SIG is establishing an agenda which embraces both elementary and secondary education and high education. We also deal with both management and public policy issues. We will continue working on the intellectual and operational challenges to system dynamics of the PK-20+ concept of lifelong learning from prekindergarten to continuing adult education, reaching beyond the usual silos separating the domains. Come tell us what you are working on, or just ask questions.
There exist many examples of organizations which failed to react to environmental change. Polaroid and Digital Equipment Corporation (DEC) are just two of them. While existing literature in particular focuses on organizational inertia and routines as impediments to change, attention to stakeholders has not received much consideration outside the area of business ethics. Since attention proved an influencing factor at Polaroid, DEC, and in a change process of the New York Stock Exchange, the interrelationships between inertia, attention, and change will be analyzed in the present paper. Stakeholder attention proved to be influenced by stakeholder pressures as well as an influencing factor on the perception of stakeholder pressures. Additionally, sensitivity analyzes revealed how different policies for managerial intervention work by themselves and in interaction.
In this brief communication, we argue for more systematic and self-conscious attention, within the field of system dynamics, to the process of knowledge sharing for the purposes of model construction. After explaining our rationale, we provide a number of examples showing how various groups of people---often those with central roles in the problems being modeled---are marginalized, their voices mute or silent. We recognize the valuable work of a number of SD modelers, emphasizing their work in western, often corporate, worlds. However, there are special problems that emerge when important members of the would-be client population are comparatively powerless, under-educated or even illiterate, as is the case in many international natural resource contexts---contexts likely to become more important as attempts to cope with climate change increase. We then provide some practical suggestions for addressing such communication problems. We believe that SD can be of great value in the analysis of natural resource conflicts, climate change mitigation and adaptation, the development of improved management systems, and in policy formulation and evaluation. The anthropological perspective may provide insights that will allow for better integration of the views of marginalized peoples into SD models.
During a long time, studies on project management were focused on duality between temporary organization (the project) and permanent organization to explain the lack of learning form the project. If the literature review emphasizes learning process and knowledge production during life cycle of project, they both disappear once the project finishes because of a lack of knowledge management capitalization. However we think that the real causes of the success or failure of the projects find their roots elsewhere that in knowledges capitalization. From our point of view, the performance of the project could be explained starting from the concept of the organizational capacity of the project team. The organizational capacity is a collective skill. It authorizes to combine and go into action relevant resources, as teams project attitude (motivation) and teams project aptitude (innovation), organizational competences focused on good relationship at work, coordination, tasks integration, etc . In this way we have developed a dynamic model of projects performance based on organizational capacity. From this model and one of the main question results from this model is: Could organizational capacity improve the project path and behind the success or failure of the project?
An earlier Conference paper used a small model to illustrate oscillations in local responses to health disparities. It was noted that further work would address medium term trends and thresholds shaping public action to eliminate health disparities. This paper begins to address those issues using Heckathorns model of The Dynamics and Dilemmas of Collective Action. Among many other things the model illustrates the implications of hypotheses related to the relative fitness of voluntary action, norms of reciprocity and selective incentives or sanctions. The hypotheses can be used to explore implications of the governance variable in the causal loop diagram adopted by the WHO Commission on Social Determinants of Health. The conclusion is that the model (a) provides a framework for analysing elite responses evident in decisions made and avoided by governance groups with duties to promote public health, and (b) has the theoretical depth necessary to be recognised as a canonical situation model as defined by David Lane.
The paper investigates the potential of urban transit buses to provide an early market for hydrogen proton exchange membrane fuel cells (PEM FCs) in road transport. System Dynamics has already been used to explore the transition towards the large scale use of hydrogen fuel cells in road transport as a whole. Given the importance of establishing early and niche markets first, on the route to mainstream markets, this paper focuses on one early market in road transport which is considered to be particularly important: urban transit buses. A System Dynamics model has been developed in order to address this particular market in detail. The model is currently still being refined; however results generated so far suggest that the market uptake of PEM FC buses will not be rapid and will require significant public support.
Global climate change is affecting the rain-runoff process around the world since pre-climate change normal rain patterns are giving way to short periods of strong precipitation, followed by long periods without rain. In addition, temperature and evaporation are expected to increase about 20% over the next 20 years. The State of Guanajuato in Central Mexico utilizes 87% of all available water for agricultural production and is extremely concerned about the impacts of climate change on water supply and demand for its various uses in the short and medium term. To explore the future impacts of climate change in Guanajuato a two-component approach was developed: (1) an atmospheric interface that generates synthetic precipitation, temperature and evaporation time series; and simulates the characteristics of these three meteorological variables and (2) a system dynamics model that beginning with the rain-runoff process generates time related behavior for natural and man-made process for each of 13 watershed that make up the States geography. Base Line and Climate Change scenarios have been generated from the present through 2030 to examine the impacts that this phenomenon is having on each watershed; recommendations have been drawn to assist these areas in adapting to new climate conditions.
Shared capitalism is a set of compensation practices (e.g., employee ownership, stock options, and profit sharing) through which worker pay, or wealth, depends on the performance of the firm or work group. Empirical studies on whether employee ownership improves firm performance, while predominately positive, offer mixed results. This paper addresses the question: under what conditions do shared capitalism policies improve firm performance? A system dynamics model of high performance work systems estimated using the NBER Shared Capitalism dataset and calibrated to a clean technology startup company is presented. The model posits explicit causal mechanisms to explain how various shared capitalism policies and human resource practices influence employee behaviors that drive business processes, and how those business processes interact with market conditions to generate firm performance. Simulation analyses demonstrate that employee ownership and profit sharing create and mediate the strength of multiple reinforcing feedbacks linking firm performance and employee behavior. The more wealth is shared through broad-based employee ownership, the more wealth is created, given the appropriate conditions. Policy analysis suggests how mutual gains for owners and employees can be attained through a balance of salary, stock grants and other shared capitalism policies.
In this paper we present our concept and prototype of a web platform which supports participatory modelling. This platform facilitates web-based collaborative and cumulative modelling when face-to-face participatory modelling sessions cannot be organized as often as desired. Successive iteration steps of the model development can thus be displayed interactively in a standard web browser together with comments and explanations made by the modeller. The platform strengthens the support of formal model construction and documentation on the one hand and reduces the effort of model re-publishing on the other hand. This platform shall be used to support participatory modelling and decision-making processes in the field of sustainable development and in many other fields.
The authors developed a Dynamic Whole System Model of Alcohol Harm Reduction for the England Department of Health, to support local commissioning of alcohol related services. The project used group model building, based on the best evidence available. It is intended to help local primary care commissioners reduce hospital admissions attributable to alcohol. The main high impact interventions incorporated are brief advice in Primary Care, the employment of Alcohol Health Workers in hospital, and Specialised Treatment. The key output measures are hospital admissions and costs. The model uses four consumption groups (Abstainers; Lower Risk; Increasing Risk; Higher Risk) including binge and dependent drinkers in more than one state. Each state has a differing propensity for hospital admissions. The model provides a dynamic cost analysis; as interventions move people between states hence changing their risk of admission to hospital. The model contains a set of policies parameterised by the Department of Health, but also allows for local settings. The work relates to the search for consistent and cohesive policies by which central government can guide local actions. The approach of using dynamic models goes beyond action lists for guidance and allows localities to learn what will work for them.
The aim of social scientists is to capture the causal mechanisms that explain behavior of people and groups of people, such as communities, societies or firms. Such an endeavor becomes increasingly difficult as theorizing concerns patterns of behavior. A theory of behavior explains how the cause-effect structure of interaction among specific variables leads to emergent paths of behavior of these variables. Thus, building theories of behavior implies creating a narrative that connects a deep theoretical structure to a repertoire of plausible behaviors that encompass the observed critical events and behaviors. A problem challenging discursive theories of behavior is the quality and robustness of inferred connections between causal structure and emerging behaviors. Equally difficult is to understand how modifications of theoretical assumptions, crystallized into a model, lead to modifications of the phenomenon under study. To make the described endeavor even more challenging, observed patterns of behavior are often produced by path-dependent processes that amplify non-systematic and stochastic disturbances. In this essay, we suggest that the interaction between field research, computer simulation and System Dynamics allows to elicit causal models from the rich texture of everyday life.
The public health community is recognizing the importance of social network dynamics in analyzing chronic diseases correlated with behaviors including tobacco and alcohol use, substance abuse, and obesity. These behaviors are driven in part by opinions that individuals hold regarding products, behaviors, and lifestyles. The opinions and behaviors of individuals are influenced by their personal social networks, as well as exogenous components, such as advertisements.
The objective of this study is to investigate a very common phenomenon in an important emerging country, namely the spike in demand at the end of the sales period, known as the hockey stick phenomenon. The analysis will encompass the causes as well as the impacts of this phenomenon, in a way that allows alternative policies to be proposed that are able to provide a better financial result for the agents involved. Data collected from a Brazilian branch of a large multinational in the non-durable consumer goods industry and in semi-structured interviews conducted face-to-face with executives of 26 clients. After internal and external validation of the model, scenarios were generated to identify causes, impacts and alternative policies. The findings showed that the phenomenon negatively impacted the manufacturers financial performance in the long term and indicated requisite changes able to eliminate it. The study showed that companies should not assume the hockey stick phenomenon to be an exogenous problem; it showed that there are alternative policies; and it provided ideas regarding ways to carry out the change process. This is the first empirical study on the hockey stick phenomenon, a problem that affects diverse companies in emerging countries.
CO2 emission of industrial facilities is a major cause of climate change that affects the ecosystems, human beings and environment. Capture, Transport and Storage of CO2 (CTSC) is a novel technology of mitigating the impacts of climate change. The uncertainties concerning long term reliability of CTSC technology give rise to the significance of risk assessment for CTSC activities.
Over the past few decades, many studies of corruption have been carried out. These studies have mainly focused on specific characteristics such as: economic issues, legal issues, and social propositions. In this article we have described the concept of modeling corruption in Pakistan using a Causal Loop Diagram (CLD). Corruption represents a very dangerous social phenomenon observed in many parts of the world. However, its manifestation in a developing country is an especially destructive agent against human development. The System Dynamics (SD) approach has been extended in the past several years through its application to new problems such as modeling state instability, supply chain management, and analysis of different nation building policies. The main objective of this study is to develop a theoretical framework which can be used to study corruption dynamics by means of SD. The methodology employed is a case study. Semi structured interviews with key stakeholders such as: government ministries, donor agencies, judiciary, police departments, non-governmental organizations and the general public are done. On the basis of literature and social theory we have developed three preliminary CLD models of corruption. The data for the qualitative system dynamics analysis comes from 30 interviews conducted in (Islamabad) Pakistan.
This paper addresses the challenge of identifying adequate theoretical starting points for problem oriented simulation studies of socio-technical transitions towards near fossil free energy services e.g. for housing and transportation. The identification of adequate starting points for simulation studies is becoming increasingly important for the generalization of simulation results as well as for theory refinement. We found that the Multi-Level Perspective (MLP) offers a helpful language for a modelling experiment based in a feedback perspective. This allows scientific conceptualization of a socio-technical transition challenge departing from an inter-subjective and hence scientific starting point. In addition feedback modelling appears to be a promising mathematical analysis approach that helps to substantiate the MLP. We have seen that the insights of the simulation experiment corroborate basics assumptions of the MLP concerning multi-level alignment processes but also discriminates the decisive determinants and governance mechanism that explain radical innovation and subsequently the creation of path dependency.
In this study, by using system dynamics approach we aim to investigate the profitability of a company if it is engaged in remanufacturing, which is the most advanced form of product recovery. Our motivation is to find out whether investing in remanufacturing is advantageous for a company/sector in terms of long term profitability and, what should be the quality and price levels of the remanufactured and newly manufactured products. The model shows that a company involved both in new and remanufactured versions of the same product, endogenously generates interesting customer-base dynamics. Different from the studies in the literature that deal with micro level models, we analyze the effects of being involved in remanufacturing of electronic products on the profitability of the firm at macro level, by taking into account the government incentives for the firms that perform product recovery.
Service operations depend intensively on human resources because of their interaction with customers and suppliers and thus, training becomes a must in order to ensure higher performance. Knowledge Management (KM) may be looked as a framework for training programs since it addresses knowledge conversion from explicit and tacit knowledge. This paper proposes that dynamic simulation might be used as a tool to analyze training programs effectiveness from a KM perspective. Thus, a SD model was built using data from a customer support service of a software-house in Brazil. Three scenarios were considered, relying on the number of trainings per month. The main contribution of this work lies on shedding light over the intangible effects of tacit and explicit knowledge that support the effectiveness of training programs over organizational performance.
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.
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.
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.
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.
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.
It is known that the presence of a supply line delay may lead to unwanted oscillatory stock behavior. It is also well known that fully considering the supply line in the ordering decisions, which means using the same adjustment time for stock adjustment and supply line adjustment terms, prevents unwanted oscillations. The effect of using the same or different adjustment times is relative. Therefore, in the literature, it is suggested that a weight coefficient should be used instead of explicitly using two separate adjustment times. This weight is simply equal to stock adjustment time divided by supply line adjustment time and it is named as weight of supply line. In this paper, we defined one more decision parameter that we call relative aggressiveness, which is equal to acquisition delay time divided by stock adjustment time. The existence or non-existence of stable or unstable oscillations is a function of the order of the supply line delay structure, weight of supply line, and relative aggressiveness. Usually, acquisition delay time and order of the supply line delay structure are not decision parameters; weight of supply line and stock adjustment time are. In this paper, we aim to give more insight to the readers about the selection of these two important parameters.
The study presents a System Dynamic model of the Nigeria electric power system. The model was developed with a view to using it to evaluate the long-term performance of the system. Both primary and secondary sources were employed to collect the systems baseline information. Results from this formed input to develop a four-sector-model in Vensim software for the long-term evaluation of the NEPS. Leverage points in the model were identified from the validated model using data from 2005 to 2009 in the Base Run. The system behaviour, based on two other scenarios (Scenario 1 representing improved basic level of consumption and Scenario 2 representing industrialization target), was then evaluated on a timeframe of 50 years starting from 2009. The study concluded that Compounded Annual Growth Rate (CAGR) and Economic Growth Rate (EGR) were the most critical policy leverage intervention points for NEPS improvement within the next 50 years.
Understanding historical overshoots is vital for policy-making, not least when assessing potentials for future global overshoots. For this purpose a simple, unifying theory of overshoots is described and discussed for a variety of observed overshoots. For undesired and avoidable overshoots, misperception at some level must be a major cause. Laboratory experiments support this hypothesis and point to dynamics as the main complicating factor. The theory suggests that misperceptions may cause global overshoots both because of climate change and scarcity of cheap fossil energy. New generations of simulation models are needed to study overshoots, test policies for sustainable development, and to aid information dissemination.
Successful corporate action requires a comprehensive recognition of the relevant cause-effect relationships. In combination with the mental models of decision-makers, and as a complement to static instruments for business management, system dynamics simulation models provide valuable support. However, due to the usually experienced big effort and the demand of specific modelling knowledge the use of such models is not yet widespread within management. In order to give medium-sized companies in particular access to such simulation models, a practice-oriented concept was developed, enabling the design and implementation of system dynamics models as to support decision-making within strategic management. Within the framework of an empirical case-study, simulation models were developed for and implemented in four production companies. In order to make the modelling process as simple, efficient, effective and relevant as possible, a practical procedure was derived out of the case studies. This procedure describes the entire modelling process encompassing the initial process of structuring the mental models, the development of quantitative simulation models, as well as the analysis of various scenarios. The concept is based on generic model components, assembled to form a fundamental model structure (backbone) in order to facilitate and to accelerate the modelling process.
This paper presents a dynamic simulation model for the study of the residential heat market in Germany with regard to the European energy targets for the year 2020. It describes the model properties and specifies the dynamic structures of the demand side based on housing units and of the supply side which is formed by heating systems. An initial model validation indicates the appropriateness of the model assumptions. Five policy scenarios are introduced which take into account different measures for the promotion of renewable and innovative heat generation technologies and obligations for energy-efficient renovation of buildings. The discussion of the scenarios shows that with the given set of policies, the EU targets for heat demand reduction and CO2 emission mitigation in the residential sector would not be met, while the envisaged share of renewable and innovative technologies seems to be achievable.
Several experiments have shown that, when predicting the behaviour of stocks and flows, many subjects rely on the erroneous correlation heuristic. They seem to assume that the output of a system should look the same as the input. Based on similar experiments with kinematics graphs we hypothesize that spatial ability explains variance on tasks involving accumulation. We propose that spatial ability might also generate other important differences between people, such as their ability to infer behaviour from diagrams. We tested participants on two dimensions of spatial ability: visualization and spatial orientation. In an experiment we found that the visualization dimension has a positive effect on performance in various systems thinking inventory tasks and a negative effect on the likelihood that the participant selects a response typical for correlation heuristic reasoning. The positive relation to performance was also present for tasks in which stock behaviour had to be inferred from text and diagrams. Furthermore, we found that people are not persistent in their use of the correlation heuristic between different types of tasks. Males and females did not differ in their spatial ability, but, males did perform better on almost all stock and flow tasks.
