The Dana Meadows Award was established in 2001 to honor the late Dana Meadows and encourage the next generation of students in the field of system dynamics. The award is given annually for the best paper by a student presented at the annual System Dynamics Conference. The winner receives a cash award, a conference registration and an allowance for travel
expenses. The Society awarded its 2012 Dana Meadows Award to David Keith at the Massachusetts Institute of Technology, and András K?vári at Delft University of Technology. David Keith received the award for the paper "Understanding Spatiotemporal Patterns of Hybrid-Electric Vehicle Adoption in the United States." András K?vári received the
award for the paper "Prostitution and Human Trafficking: A model-based exploration and policy analysis." The award was presented by R. Joel Rahn.
To help modelers increase the transparency of their models through enhanced documentation, scientists at Argonne National Laboratory (ANL), building on model documentation work by Oliva (2001), developed the System Dynamics Model Documentation and Assessment Tool (SDM-Doc) that enables modelers to create practical, efficient, HTML-based model documentation and provide customizable model assessments. The model documentation created by the SDM-Doc tool allows modelers to navigate through model equations and model views in an efficient and practical way creating documentation of the model sorted by variable name, type of variable, group, view, module, module/group/name, and variable of interest. Additionally, model tests are performed allowing modelers and reviewers of models to gain confidence in fundamental characteristics of model structure. The tool, its use, and the different model assessments included in it will be presented and explained. Participants are encouraged to bring their laptops to be able to use the tool during the workshop. A copy of the software will be distributed to participants at the workshop (the tool is accessible at http://tools.systemdynamics.org/sdm-doc/).
The purpose of this study is to build an experimental platform for scenario and policy analyses of social security institutions that deploy pay-as-you-go schemes as the financing method. To realize this aim, system dynamics methodology is utilized and a generic dynamic simulation model is constructed. Afterwards, the financial sustainability of the social security institution in Turkey, as a susceptible country for its aging population, is investigated via scenario and policy analyses. The results show that (i) irrespective of scenarios and policies, aging phenomenon is quite dominant and a serious threat to financial sustainability, (ii) informal sector plays a crucial role in the financial sustainability of social security systems, and (iii) a hybrid policy combining increase in retirement age, premiums and decrease in informal sector ratio seems to be the most promising one among the other policies. Future research involves modeling the fully funded scheme complementing this study to enable the public policy makers to compare and contrast the two financing methods comprehensively.
This paper presents a soft landing model and an experimental platform. The aim of the modeling effort is to transparently represent the process of landing a spacecraft on the surface of a celestial body. The process of landing is a challenging task because there are two main contradictory performance criteria to be met simultaneously; the landing duration should be as short as possible, but at the same time crashing the spacecraft to the surface should be avoided. If the only criterion was to prevent crashing the spacecraft, that would not be difficult to achieve by slowing down the landing process. However, long landing duration necessitates extensive use of fuel, which should also be avoided. As a summary, the main goal in the soft landing problem is to land the spacecraft as gently and as fast as possible. The model and the modeling process presented in this paper will serve as a modeling case to be used in teaching. Based on the soft landing model presented in this paper, we also developed a platform for simulation experiments. Our simulation-based discovery learning environment can be used to introduce dynamic complexity. It can also be used as an introductory control design tool for physics, engineering, and interested social sciences students.
The purpose of this study is to introduce system dynamics as a methodology to analyze intra-organizational innovation diffusion processes. Therefore, a purely algebraic model is replicated and analyzed in a system dynamics environment before it is extended by relaxing the restrictive assumption that intra-group diffusion and inter-group diffusion take place consecutively. The findings of this study suggest that the parallel occurrence of intra-group and inter-group diffusion can change the outcome of the diffusion process significantly. In addition, system dynamics is used to illustrate and analyze the complex dynamics of the diffusion process. The interplay between the self-reinforcing dynamics of intra-group diffusion and the balancing dynamics of inter-group diffusion is heavily influenced by the structure of the network between groups. The simulations suggest that adopter-dominated groups should be connected to each other, while non-adopter-dominated groups should be isolated in order to increase the probability and speed of successful innovation diffusions. Major limitations of the study are that only one network structure between groups was examined and that all groups are considered to be homogeneous.
Increasing concern regarding the cost, security, and environmental impact of fossil fuel energy use is driving research and investment towards developing the most strategic methods of converting biomass resources into energy. Analyses to date have examined theoretical limitations of biomass-to-energy through resource availability assessments, but have not thoroughly challenged competing tradeoffs of biomass conversion into liquid fuel versus electricity. Existing studies have focused on energy crops and cellulosic residues for biomass-to-energy inputs, however the conversion of these biomass resources is often less energetically efficient compared to fossil energy sources. Waste streams are beginning to be recognized as valuable biomass to energy resources. Municipal solid waste (MSW) is a low-cost waste biomass resource with a well-defined supply infrastructure and does not compete for land area or food supply, making it a potentially attractive renewable feedstock for energy conversion. The Waste Biomass to Energy Pathway model (WBEM) described here demonstrates a system dynamics approach to analyze the impact of converting MSW biomass to either bioelectricity or liquid fuel. The WBEM incorporates macro-scale feedback from supply chain costs, energy sector impacts, and greenhouse gas (GHG) production within the competing pathways of MSW to 1) landfill, 2) electricity, and 3) liquid fuel within California.
This study empirically demonstrates that software firms in a niche market with relatively short-life cycle may experience a similar growth pattern that firm grows after a period of performance deficit. A system dynamics model is built to capture the essential interactions across industry- and firm-levels. It is found that the growth trajectory of worse-before-better offers an explanation of the high exit rate in software industry in which small and medium enterprises are the majority. Furthermore, it is also found that though activities of market development and service and activities of product development and enhancement were important in pursuing survival and growth, software firms with different attitudes towards growth emphasized differently on the these activities by different human resource management and allocation policies. In this paper, we argue, and show, that entrepreneurs attitude towards growth and his or her adopted growth strategies determine how worse to experience and the extent to grow. This is significant to system dynamists because it shift our attention from traditional growth dynamics exploration to the observation and explanation of why firms experience growth or failure differently. The difference of growth among software firms and its implications is deliberately discussed.
Customer lifetime value (CLV) is the core content of customer relationship management. With the increasingly fierce market competition, more and more enterprises realize the importance of maintaining long-term strategic partnership with customers. In this paper, we established a system dynamics model of CLV and use SF Company as an example. The model simulation results showed that the intensity of competition, price levels and investment levels all affect CLV. Reducing the intensity of competition can increase the CLV. More investment will raise service quality and then promote CLV. Reducing the price level increases CLV in the short term. However, in the long run, less income leads to less profit and less investment which can decrease CLV.
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.
This paper introduces the industrial transformation model applied to the carmaker industry. We analyze the interaction between supply and demand as well as policy regulations supporting the diffusion of advanced vehicle technologies. It allows to assess prospectively threats and opportunities of induced technology changes for industries. The simulation exercise provides evidence that smart governance approaches involving concerted entrepreneurial and political decision making can avert severe industrial crisis of adjustment during phases of socio-technical transitions. The overall cycle pattern seems to play out over a time period of 50 years. It is strongly influenced by the climate policy regime and the innovation investment behavior of firms. It results in a sectoral boom phase once the transition towards near zero emission vehicles has been mastered. The policy induced technology change pattern is comparable to the long wave theory in terms of its duration and the argument, that deep structural causes are innovation processes in whole technological systems. Moreover, we have identified the drivers of single short term cash cycles. Differences between cash inflow and outflow over time that are triggered by strategy and policy changes explain short term fluctuations.
Over the past few decades, many studies of corruption have been carried out. These studies have mainly focussed on specific characteristics such as: economic issues, legal issues, social propositions, impact on national development, and in relation to economic policy. The rationale of this research is to build initial system dynamics models of corruption, so that these models can extend our understanding of corruption and act as an input to future policy making on corruption. System dynamics modelling allows researchers to discover hidden dynamics. Moreover, system dynamics enables the analyst an increased level of flexibility, as system dynamics modelling uses both theoretical understanding, as well as empirical data collection. Indeed, as a result of this study, we can offer an explanation that uncovers the underlying factors that address the dynamics of corruption, social, economic, political, judicial and cultural factors in case of any developing country, which can be applied with some modifications for developed world. In this we try to determine problem of corruption in societies by incorporating very complex and different social, cultural and even religious aspects that were mostly untouched in system dynamics studies in past. Systems dynamics model of corruption developed in this study would be of use to policy makers and non-governmental organisations in understanding the complex nature of corruption.
Accounting Dynamics (AD) is a methodology of accounting as social science. We studied Accounting Dynamics from 1982 to 1994. We first proposed the concept of Accounting Dynamics on International System Dynamics Conference in 1987 . We interrupted the study for a long time, because there were some difficulties to develop the real Accounting Dynamics models. The concept is still reasonable and so attractive that we have reviewed Accounting Dynamics again. This is first step to restart the project and show you Accounting Dynamics in order to organize the SIG. This paper shows what is "Accounting Dynamics" clearly.
There are many studies exploring the reasons behind failures in solving generic system dynamics (SD) problems such as stock- flow (SF) failure. Although they reach some limited associations, they do not find any significant cognition related factor explaining the variation in failures except the positive impact of visual saliency of the problem displays. In present study we put forward the question Does cognitive problem solving capability improve progressively? So, we prepare a performance sheet including two parts. First part consists of simpler SF problems and second part contains more complex ones. Then we ask these questions to motivated undergraduate industrial engineering students. Sample of participants consists of two groups. First group is SD educated and second group is not SD educated. We see that while some individuals are performing well in solving more complex SD problems, others are performing well in simpler ones, and ability to solve more complex problems is not dependent on performance in solving simpler ones. But we find associations between capabilities of solving two different more complex SF problems each other. We also see that SD education increases the capability of solving more complex SF problems but does not affect the capability of solving simpler SF problems.
Inter-firm trust is an essential element in supplier relationship that shapes the collaboration and coordination between suppliers and buyers. In this paper, we use system dynamics as an approach and perspective to analyze the evolutionary process of supply chain collaboration. Use a valve manufacturing firm as an illustrative case, this paper illustrates how a buyer firm in a networked supply chain unexpectedly harmed the inter-firm trust between the buyer and its suppliers that further resulted in the collapse of the relationships among them. Based on the quantitative system dynamics model developed, this paper argues and shows that supply chain relationships may be more complex than the consideration of transaction costs. Path dependency of the make or buy decision may exist and drive a supply chain to evolve over time. Buyers and suppliers rational decisions to reduce their own risks and to optimize efficiency may not only interfere with the benefits of the other side but also entrap a long existed supply chain to collapse. From the economic perspective, how to balance the time required for capacity expansion and the time for suppliers to develop new customers is of the essence in such a vulnerable supply chain setting.
Presented here are strategic planning tools used at a State University, College of Business. Four distinct tools are presented: The Strategic Initiative Scoring Model, which communicates how the college strategic planning execution projects fit the strategic priorities of the Universitys mission statement & strategic plan; the college Strategic Risk Planning Matrix, which describes both risk assessments and risk management plans; the college Strategic Planning (SD) Model, which is used by administrators to assess impacts from proposed or mandated changes in budgets, admissions, Student-Faculty Ratio targets, and faculty hiring/attrition; and the Strategic Performance Indicator matrix, used to monitor performance and drive the creation of new projects to be assessed in the Strategic Initiative Scoring Model.
Human resource requirements planning for nursing capacity has traditionally focused on expected utilization or demand and largely ignored the complex workplace policies. The approach taken in this research emphasizes the interaction of policies affecting compensation, work intensity, task satisfaction and career progression on hiring and retention the flows that determine the stock of nurses. Based on research conducted with Singapore Ministry of Health, we describe how policy changes influence employment levels at care venues over a strategic time horizon. To answer three research questions posed by experienced planners and managers, we employ a System Dynamics model to test and explain the implications of alternative policy choices.
A water cycle analysis System Dynamics model for designing an optimal reclaimed water production scheduling is proposed. A water cycle has various types of water flow and storage, so System Dynamics is suitable for modeling and simulating it. In addition, by using System Dynamics modeling software, various types of models for water cycle analysis can be modeled comparatively easily and used to design an optimal scheduling. The model must be able to analyze water quality and energies for water distribution and treatment as well as water flow and storage in order to schedule optimal production. It therefore consists of three components: water flow, water quality, and energy models. We constructed a water flow model that can handle various types of water flow. The Energy model computes the energy consumption of the pumps and blowers used in water distribution and water treatment systems, and the water quality model computes the water quality of treated wastewater and reclaimed water. Our constructed model was used to schedule water reclamation production to reduce the energy consumed during the water reclamation process and to ensure high quality of the reclaimed water. Simulation results showed that the proposed model is effective for designing an optimal scheduling.
Methods of systems analysis were applied to the illness multiple sclerosis (MS). By mapping causality among the many causes affecting multiple sclerosis, we have been able to show that it is a systemic illness, with multiple interacting causes and mechanisms. By using causal-loop diagrams we synthesized a systemic picture of MS in which the role of allergies, pathogens, molecular mimicry, venous vascular dynamics, membrane stability, immune system, and oxidants-antioxidant dynamics were integrated. There are important components that make up MS:
The TETRA-model has been built to predict the modern occurrence of ancient Athenian tetradrachm silver coins in quantitative terms, based on their original minting volumes an antiquity and the processes of their loss and destruction, as well as the process of finding them in modern times. The conceptual model was developed as causal loop diagrams and flow charts, based on Athenian siver mining dynamics, the minting process, the circulation in trade and finance in ancient Athens, rates of wear and loss of coinage, corrosion of coins in the buried state, modern retrieval rates and dynamic turnover in the numismatic market, as well as deposits into collections and museums. A systems dynamics model was programmed in the STELLA modeling environment and implemented for 500 years of Athenian coin production (526 BC to 42 AD) and preservation and retrieval until the present (526 BC to 2010 AD). The TETRA model was tested against independent estimates of past and present coin volumes, treasure finds, museum stocks. The model seems to work well in tests against independent estimates. The approximate number of coins surviving until today for the different types such as archaic owls, classical owls, transitional owls, heterogeneous owls and new style owls were predicted well within the estimates derived through other means and museum inventories (r2=0.82).
By using an integrated dynamic model we are able to reconstruct the supply and gold price of the past (1920-2010) and this is used to predict the future supply of gold to the market and to make a forecast of the gold price 2010-2100. The model was validated against field data for the period 1920-2010 and it performs well. The simulation results show that the market is fundamentally driven by supply and demand, but that derivates trade and speculations have affected the market significantly to create large short term variations in price. In the long term, the model predicts a shift from high-grade ores to low-grade deposits as the main supply source in the next 50 years, but that recycling will become the most important source of gold to the market. The authors predict a significant tightening of the gold market, with rising prices and a decreased derivates trade as compared to trade in the physical commodity. The model shows clearly that foreward and derivates trade create less stability and increase price fluctuations, but that they cannot prevent the long term trend from basic fundamental factors to set the long term levels.
Adaptation of SD mainly focuses on management and environment aspects, and successes to get enormous reputations from results. However, adaptation of SD is not limited on these areas, but disseminating to psychology and military science recently. Author believes such adaptation should be wider to other fields too. Continuous of such adaptation, this paper tries to build SD model for study literature with quantitative explanation and understanding. William Shakespeares Tragedy of Romeo and Juliet is one of best works in his early age. Similar story also looked in other literatures in other countries including works of Chikamatsu Monzaemon in Japan and opera Tristan and Isère. Added more, Romeo and Juliet was adapted to other forms of arts and literatures including Broadway musical West Side Story.
The main aim of this paper is to study the impact on birth rate of specific public policies: subsidies to chilbearing and public consumption. The analysis is framed in an developed economy in which fertility choices and economic decisions are interconnected. In particular, the study relies on overlapping generations, habit formation in consumption and endogenous fertility rate. This last factor is directly explained by the preference for children, the economic capacity of young people and the stylized fact of unemployment. The outcome is a versatile system dynamics model that is adapted for the Portuguese economy from 2000 to 2011. Two counterfactual exercises differentiated from the employment distribution but with identical alternatives of public spending are implemented in the simulation model. The results show two divergent aspects: the births do not vary if the public consumption increases but, the births increase when the costs of childrearing are subsidized even if the public consumption is high. These results also indicate that the subsidies are not sufficient to curb the decreasing trend of births. In addition to them, it is required a sustainable economic growth.
In the last decades in several mature democracies the problem of debt emerged as a violation of intergenerational equal treatment due to high expenditures concentration and dilution of costs by mean of debt creation. So far this issue has been analyzed from a statistical and a socio-economic perspective, which identified the high political interference as the main dysfunction of country debt management. There are no studies which frame the issue by focusing on State institutions as performance-oriented organizations, according to this perspective such organizations have to respect dynamically trade-off between development and the debt reduction through a mix of levers such as: funds acquisition/reduction, interest rate and financial leverage. System dynamics can be successfully used as an instrument to support Government in keeping control over the key variables affecting debt changes and implementing a sustainable policy. In the paper three kinds of policies are recommended: the reduction of expenses and increase of receipts in the short term to drastically reduce the debt amount; the opportunity to exploit the financial leverage in the long term. Such approach implies a change of perspective, looking at Italy as a performance-oriented organization in which a proper financial management serves economic development and not vice versa.