Online Content

81. Osgood, Nathaniel, "Representing Progression and Interactions of Comorbidities in Aggregate and Individual-Based Systems Models"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/b85165912?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:44Z
Description:
Health policy models have attracted significant offered important insights in to health trends and policy selection. More complete accounting for the cost and health implications of upstream interventions is hindered by the need to consider impact on, and interactions between, multiple comorbidities. Within this paper, we explore several distinct approaches for representing comorbidities, some of them at the aggregate level, and some of them at the individual level. All of these representations have the virtue of being declarative, in that they allow the user to focus on what is to be characterized, rather than how it is to be implemented. Our exploration suggests that while several aggregate representations of comorbidities are possible, they suffer from a variety of shortcomings, ranging from low fidelity to combinatorial blowup. While individual-level representations impose a heavy performance load, greater difficulties in calibration and less rapid analysis, such representations do offer greater transparency, modifiability, scalability, and modularity, and ease of representing transmission and influence networks. With much to recommend each approach, further research is needed to shed additional light on the tradeoffs and identify situations where one representation is preferable to another.

82. Nilsen, Trond with Brian Houle, Douglas Kuzenski and Arpan Sheth, "Exploring the Dynamics of Music Piracy"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/ms35tt90g?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:43Z
Description:
Recently sales of physical music media have declined along with music industry revenues – the reasons are complex and poorly understood. We present three models exploring claims made in the conversation over piracy and the music industry's future. We model stakeholder perspectives rather than the full industry to identify their assumptions and the implications of their views, including: (1) Music industry labels claim music piracy directly supplants music sales; (2) Artists claim free music distribution can increase artist revenue through concert sales; and (3) Some academics claim reduced music sales revenue is attributable to other market changes (e.g., increased entertainment competition) rather than piracy. Modeled results suggest that, for each claim respectively: (1) Music labels' mental models are simplistic and do not reflect current research findings; (2) Artists can enhance their concert revenues through piracy as free marketing; and (3) competition with other media explains part of declining music industry revenues.

83. Nguyen, Phuong Linh, "The Long Runs Effects of Competitive Undervaluation of Dong Currency on the Economic Growth of Vietnam"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/v405sv47v?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:42Z
Description:
After joining the World Trade Organization, Vietnam attracts more and more foreign investment. Large increase in foreign capital has been led to an overheating economy. Vietnam has been depreciating its currency over the last several years compared to the dollar, making Vietnam’s exports to the U.S. lower-priced. In short run, it helps Vietnam to increase the exports and boost national income. However, in the long run, it is expected to negatively affect the economic growth. Since imports become expensive because of undervalued currency, Vietnam can not afford to update the technology improvements. With the lack of updating on technology improvements, it is impossible to maintain per capita growth. The impacts on technological growth in Vietnam, measured as Total Factor Productivity, can affect the per capita growth of Vietnam. This paper investigates what long term effects on the economy of Vietnam when the Dong currency is undervalued.

84. Newton, Paul with Michael Richey and Mohammad Mojtahedzadeh, "STEM Pressures from Birth to Globalization: Five Related Models"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/h989rm762?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:41Z
Description:
In the U.S., there is progressively more concern about the impact that changes in science, technology, engineering, and math (STEM) skills might have on the future of U.S. prosperity. In parallel with their many STEM initiatives, industry, education, and government are engaged in multi-faceted STEM policy conversations, both among themselves and with the American public. We know of five system dynamics models that have been developed toward the objective of improving these STEM policy conversations. In this session, Boeing, as catalyst for development of three of these five models, will outline the STEM problem, summarize and lightly compare the five models, and present one of the models. The model presented here arose from a reading of the National Academies' report, "Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future." The model focuses on the reinforcing feedback between U.S. prosperity and the U.S. Science and Technology Enterprise, and concentrates attention on how education, R&D investment, and immigration policies might act to strengthen or weaken that feedback. Thus, this model provides a dynamic conceptual framework within which one can place the other four STEM models to be presented in other sessions at this conference.

85. Musango, Josephine with Alan Brent and Andrea Bassi, "South African Energy Model: A System Dynamics Approach"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/2n49tk494?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:40Z
Description:
This paper provides a South African energy model that was developed as a first step towards a comprehensive Threshold 21 model for South Africa. The energy sector consists of five sub-models, which are structured around the supply and demand of electricity, coal, oil, and natural gas in the sector. The model was used to examine a set of policies that the South African government is currently considering, e.g. expansion of nuclear energy production and implementation of more stringent energy efficiency measures. The analyses show that energy efficiency measures are indeed the best option to curb the supply and demand constraints, which the energy sector faces, in the short term. In general, the paper demonstrates how a system dynamics approach can be utilized effectively to support understanding of energy-related issues and clarify the advantages and disadvantages related to the options available to government and the private sector. The paper also highlights potential pitfalls that may be encountered when building such a model. Future developments include extending the model to incorporate the linkages between the energy sector and the economy, society and environment, which would complete the T21 framework for South Africa, and extending the model, with models for other countries in the region, to the Southern African Development Community

86. Moxnes, Erling, "Are advice adhered to? Populist versus activist or expert advice."

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/cv43pf487?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:39Z
Description:
Laboratory experiments of decision making have revealed widespread misperceptions of nonlinear dynamic systems. A possible criticism of these experiments is that participants do not get the advice they may receive in real situations. Here we repeat one previous experiment where we add two conflicting advice. A 'populist' advice reflects typical misperceptions while a second advice represents a near-to-optimal policy. The latter advice is in the wording of an 'activist' in Treatment 1 and in the wording of an 'expert' in systems analysis in Treatment 2. The results suggest that advice, including near-to-optimal ones, may have minor effects in complex systems. Activist wording seems more effective than expert wording, with the possible exception for participants with a certain background in stock and flow reasoning.

87. Moxnes, Erling, "Peak oil, biofuels, and long-term food security"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/zc77t828w?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:38Z
Description:
Recent oil prices escalations, current production of biofuels from food, and rising food prices have caused an awareness of a potential conflict between biofuel production and food availability. Biofuels could help countries reduce their dependence on imported oil and biofuels could lead to some reductions in CO2 emissions. For such reasons governments have stimulated research and development and subsidized biofuel production. In this study we use a simulation model to study how markets for oil, biofuel, and food may interact and develop in the long run as world oil production peaks and starts to decline due to resource depletion. We hypothesize that a shortage of oil will make biofuels highly profitable, lead to a take-off for the biofuel industry, and lead to food shortages and starvation. We do not reject this hypothesis. A number of policies all tend to delay rather than cure the problem of food shortage. Therefore it seems urgent to start discussing and building support for a ban on biofuel production from food.

88. Moxnes, Erling, "Optimization under uncertainty in SD models"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/bn999r750?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:37Z
Description:
People have difficulties making good decisions in the presence of uncertainty and in nonlinear dynamic systems. When these challenges are combined, decision problems get even worse. The workshop gives an introduction to optimization under uncertainty in such systems. This is normally a very complex undertaking. However, it has been greatly simplified by the new software SOPS from Powersim Software. After the introduction, participants get hands-on experience with SOPS.

89. Morrison, J. Bradley, "The Problem with Workarounds is that They Work"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/vt151314f?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:35Z
Description:
Resource shortages are a fact of life in most organizations and in the currently challenging economic climate will be even more common. There is little doubt that resource shortages are widespread and that they lead to undesirable outcomes, yet there has been surprisingly little attention to questions about why they occur and even more insidiously why they persist despite the apparently clear adverse consequences. This paper develops a grounded theory that helps to understand chronic resource shortages, drawing on data from field work at a manufacturing firm adopting lean manufacturing. The paper examines how the actions of various groups (e.g., managers, production workers, and other shop floor workers) interact with each other and with the physical characteristics of the workplace to sustain problematic resource shortages. The paper uses a causal loop diagram and a stylized system dynamics model to highlight some important features of the dynamics.

90. Moosavi Haghighi, M. Hashem, "Combination of Econometric Methods and System Dynamics Approach to Improve the Iranian Agricultural Policies"

Type:
Document
Date Created:
2009 July 26-2009 July 30
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, b3584c6b53c3f58e0202549d7d851f84, and 4818cb531cdd68d6ec6af3f291216fc7
Thumbnail Path Ss:
/downloads/qz20tb21t?file=thumbnail
System Modified Dtsi:
2020-01-02T19:51:34Z
Description:
Agriculture is an important economic sector and a strategic component for the rural development in Iran. However, the sector has been beset by a labour surplus situation. This situation, together with inappropriate combination of labour with other factors of production, has caused a low growth rate in the agricultural production. The main objective of this study was to determine the optimal employment and production policies in the Iranian agricultural sector. Then, production, export-import, demand for labour and agricultural products, as well as the wage functions were estimated using the data collected during 35 years, and substituted in the economic component of the System Dynamics (SD) model to simulate the outcomes. The results indicate that a downward turn for the labour surplus problem will happen in 2008. Afterwards, the agricultural employment will gradually decline. Consequently, the cityward migration will increase, and the unemployment problem shifts from the rural to the urban areas. The average annual production growth rate in the 2007-2021 period is estimated at 1.8%. Furthermore, higher production is commensurate needed with substantial investment and adoption of appropriate technology. This study further demonstrates that combination of the SD approach and econometrics methods is highly effective in arriving at logical answer.