Problem definition, as system dynamicists believe, is the most important phase of the system dynamics modeling process. However, its literature is not rich enough so as to match its importance. In this paper, by reviewing the literature, we introduce the idea that the problem definition itself has an iterative and evolutionary nature. Here, we propose an approach to develop and enrich problem definition based on continuous and conscious effort to elicit the hidden ambiguities of the dynamic hypothesis and transform these ambiguities into questions whose answers would precise the definition of the problem and improve the dynamic hypothesis. We show how this approach on one hand can help us build models much more suited to dynamic real world problem and on the other hand help us much more effectively use models to understand and solve these problems. Finally, we propose some guidelines for revealing the ambiguities as basis to the problem definition and dynamic hypothesis in an iterative process.
Cat Ba Archipelago in Viet Nam has been recognized as a world biosphere reserve. This biosphere is identified as the highest biodiversity in the country and a priority for global conservation. Cat Ba, the largest Island in the archipelago, features diverse topography, remarkable historical heritage and archaeological value. Because of these unique features, the Island has become a popular tourist destination. Cat Ba is experiencing a strong growth in tourism. However, a number of challenges pose threats to sustainable tourism development in Cat Ba including environmental degradation, high poverty level, overuse of underground water, lack of fresh water and electricity, lack of skilled labours, and poor infrastructure and recreational facilities. This paper seeks to explain how a complex and dynamic tourism systems model can be developed and used as framework for decision making and capacity development for local government and private stakeholders who share the responsibility of sustaining the system. The causal loop diagrams and stock and flow models have been developed with participation of diverse stakeholders. Alternative scenarios will be analysed to explain how tourism in the biosphere may change in the next 10-20 years as a result of both multiple investment strategies and changes in the external environments.
This paper describes formative field research to develop and test the utility of a system dynamics modeling intervention intended to promote evidence-based tobacco treatment practices in community-based primary care settings. Brief counseling interventions by primary care providers have been shown to effectively promote tobacco cessation among patients who smoke, yet many physicians are inconsistent in the way they intervene with their patients. Too little time, poor training, lack of third-party reimbursement, competing clinical problems, and the belief that their patients are not able to change explain, in part, why some physicians do not adhere to evidence-based guidelines for treating tobacco use and dependence. Via a protocol for conducting on-site office visits to small primary care practices located in medically underserved urban communities, we tested the hypothesis that providers exposed to the simulation tool would demonstrate better understanding and progress towards full implementation of the US Public Health Service Guideline for Treating Tobacco Use and Dependence. Results indicate that simulated output that reflects the dynamics of providers unique practice environment is associated with stronger behavioral intent than other forms of feedback information, such as patient chart reviews.
In recent years, due to fast development of information technology and fierce competition, information technology investment strategies are significant factors to sustain business operation. Furthermore, rival investment strategies and allocation of complementary assets should be taken into account so as to achieve maximum efficacy of the strategies. This study adopts the intellectual capital structure and complementary asset theory, and investigates Taiwans information-intensive services. A research model is presented to discuss the impacts of information technology investment strategies on organizational performance based on intellectual capital framework. This study introduces a system dynamics method to analyze a case of two rival companies, and interprets the effects of different IT investment strategies on operation performance through simulation and scenario analysis. The simulation results can help companies making information technology strategies and evaluating their overall performance. The results indicate that different information technology investment strategies and matching degree of complementary resources have different impacts on the organizational performance. Moreover, this can help companies to make IT investment strategies. The studied results can provide important theory and practice implications for organizational IT management.
Bounded by limited cognitive capabilities, decision-makers use mental models (reduced versions of real world dynamics) for decision-making and interventions in complex tasks. As such mental models are constantly updated with new experience and knowledge acquired, facilitating a learning process. Through this learning process, mental models can be refined to better represent real world dynamics. Systems theory suggests that updates of mental models happen in continuous cycles involving conceptualisation, experimentation, and reflection (C-E-R), which represents a dynamic decision-making process (DDM).
In recent years, new business models are becoming increasingly more important for manufacturers in the capital goods industry. However, manufacturers of plants still hesitate to offer these customer-oriented solutions, due to existing uncertainties resulting from economic risks. The offer of innovative business models requires a stronger integration of the supplier into the life cycle of a plant and hence into the production phase of the customer, leading to the consequence that manufacturers have to restructure their previous activities extensively. Due to the financial risk connected herewith, decision models are required, which identify and assess the impacts resulting from the implementation of these innovative business models. Aspects like time delay, due to the reorganisation of the service department or the set up of adequat human resources have to be considered. Therefore, the aim of this contribution is to develop a system dynamics model for the analysis of long-ranging consequences due to the implementation of an exemplary business model.
In this paper, the ecological footprint of Macao from 2000 to 2020 is studied using Stella modeling and theories of system dynamics. From our modeling, the value of EF per capita of Macao increases from 3.3ha/capital in 2000 to 4.6ha/capital in 2020. It is the first time that such values are reported and they are valuable to policy makers in Macao. In details, the model consists of three modulesecological footprint (EF), city and tourism modules. According to the simulation results, the EF per capita is increasing continuously. Population increases from 434, 070 in 2000 to 562,600 in 2020, and tourists increase from 2,175,800 in 2000 to 9,731,180 in 2020.It is shown that fossil energy land is the key factor influencing the EF of Macao and is affected mainly by city development. Besides, city development is limited by two factors, namely population and available land. The available land for business and housing is becoming scarce. On the contrary, energy price has limited affect on city development. Consequently, it also has limited effect on fossil energy land. Key Words: Macao; STELLA; ecological footprint; model
Ineffective policies of the resource management in services businesses can produce undesirable effects such as oscillation between acquisition and release of workforce, and amplified oscillation of workforce level through the stages of the service processes. We apply control theoretic principles in managing workforce to see how various PID feedback control schemes can improve costs, utilization and stability of workforce in response to demand disturbance in services supply chain. Our study through a system dynamics model indicates that effective combination of PID feedback control schemes can produce desirable policies of workforce resource management.