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We present a practical guide and step-by-step flowchart for establishing uncertainty intervals for key model outcomes in a simulation model in the face of uncertain parameters. The process starts with Powell optimization to find a set of uncertain parameters (the optimum parameter set or OPS) that minimizes the model fitness error relative to historical data. Optimization also helps in refinement of parameter uncertainty ranges. Next, traditional Monte Carlo (TMC) randomization or Markov Chain Monte Carlo (MCMC) is used to create a sample of parameter sets that fit the reference behavior data nearly as well as the OPS. Under the TMC method, the entire parameter space is explored broadly with a large number of runs, and the results are sorted for selection of qualifying parameter sets (QPS) to ensure good fit and parameter distributions that are centrally located within the uncertainty ranges. In addition, the QPS outputs are graphed as sensitivity graphs or box-and-whisker plots for comparison with the historical data. Finally, alternative policies and scenarios are run against the OPS and all QPS, and uncertainty intervals are found for projected model outcomes. We illustrate the full parameter uncertainty approach with a (previously published) system dynamics model of the U.S. opioid epidemic, and demonstrate how it can enrich policy modeling results.

Local communities sometimes face severe shocks, such as the COVID-19 pandemic or economic recession, which inflict widespread harm, intensify injustice and test the ties that bind people together. A recent “Springboard” theory proposes a way to spring forward toward an equitable, thriving future by altering priorities among four structural drivers of population well-being: the extent of vital conditions, equity, urgent services capacity, and belonging and civic muscle. To explore the strategic implications of the Springboard theory, we developed the Thriving Together Model, a system dynamics simulation model that lets users play out alternative investment priorities and track changes over a decade as they try to maximize the number of people thriving and minimize suffering. The prototype model is exploratory, subject to further refinement and empirical support, but it has already sparked creative conversations among hundreds of changemakers who have interacted with it through an interactive theater. This paper presents the model’s structure, illustrative results, and tentative insights. The Thriving Together Model extends Ostrom’s Nobel Prize-winning work on shared stewardship by offering a general explanation about how stewards of a divided community can heal through a traumatic shock and spring forward toward a future with greater well-being and justice.

The growing burden of chronic disease represents a complex challenge to public health. Innovative approaches, such as system dynamics simulation modeling, can aid public health professionals in understanding such complex issues and identifying effective solutions. This paper describes a system dynamics model and its application in projecting the impacts of evidence-based interventions on chronic disease for the state of Colorado. The development of the model was guided by data and input from subject matter expertise, peer-reviewed literature, and surveillance data. The model includes 28 intervention levers for chronic disease prevention, screening, and management. Interventions were simulated from 2020 to 2050 to project their impact on ten preventable causes of death. The simulations indicated the 6 most impactful interventions by 2050 to be adult smoking prevention, diabetes prevention, smoking cessation, blood pressure management, adult physical activity promotion, and colorectal cancer screening. Together, these 6 interventions could reduce preventable deaths by 7.1%, or 74% of the 9.6% reduction from all 28 interventions combined. This system dynamics model is a flexible tool that could be adapted or extended to include other populations or preventable chronic diseases. Prioritization and wide-scale implementation of the most impactful interventions could significantly reduce preventable deaths resulting from chronic disease.

Many believe good government to be essential for a nation’s progress, but, in fact, governance is a multidimensional concept with uncertain implications for economic development and global sustainability. The World Bank has tracked six country-level Worldwide Governance Indicators since 1996. Statistical regression analysis across 150 countries identified two of these indicators, Government Effectiveness and Regulatory Quality, that consistently help to explain changes in economic growth and CO2 emissions. The regression results provided the evidence needed to incorporate the effects of governance in an existing climate-population simulation model. Policy testing of the revised model led to findings about what improved governance can and cannot do. The testing suggested that the best combination of such improvements could boost progress on emissions reduction without hindering economic development—but not enough to strongly mitigate climate change. Achieving the double goal of economic development and strong climate change mitigation would thus require some kind of extra effort that does not fall under the usual definitions of good national governance.

Abstract Objective: To assess the usefulness of a national and a local system dynamics model of cardiovascular disease to planning and funding decision makers. Methods: In an iterative process, an existing national model was populated with local data and presented to stakeholders in Counties Manukau, New Zealand. They explored the model's plausibility, usefulness and implications. Data were collected from 30 people using questionnaires, and from field notes and interviews; both were thematically analysed. Results: Potential users readily understood the model and actively engaged in discussing it. None disputed the overall model structure, but most wanted extensions to elaborate areas of specific interest to them. Local data made little qualitative difference to data interpretation but were nevertheless considered a necessary step to support confident local decisions. Conclusion: Some limitations to the model and its use were recognised, but users could allow for these and still derive use from the model to qualitatively compare decision options. Implications: The system dynamics modelling process is useful in complex systems and is likely to become established as part of the routinely used suite of tools used to support complex decisions in Counties Manukau District Health Board.

Numerous local interventions for cardiovascular disease are available, but resources to deliver them are limited. Identifying the most effective interventions is challenging because cardiovascular risks develop through causal pathways and gradual accumulations that defy simple calculation. We created a simulation model for evaluating multiple approaches to preventing and managing cardiovascular risks. The model incorporates data from many sources to represent all US adults who have never had a cardiovascular event. It simulates trajectories for the leading direct and indirect risk factors from 1990 to 2040 and evaluates 19 interventions. The main outcomes are first-time cardiovascular events and consequent deaths, as well as total consequence costs, which combine medical expenditures and productivity costs associated with cardiovascular events and risk factors. We used sensitivity analyses to examine the significance of uncertain parameters. A base case scenario shows that population turnover and aging strongly influence the future trajectories of several risk factors. At least 15 of 19 interventions are potentially cost saving and could reduce deaths from first cardiovascular events by approximately 20% and total consequence costs by 26%. Some interventions act quickly to reduce deaths, while others more gradually reduce costs related to risk factors. Although the model is still evolving, the simulated experiments reported here can inform policy and spending decisions.

The article reflects on developments in world disarmament. It states that there has been a lack of progress in disarmament because there is also a lack of leadership between the two powerful nations, United States and Soviet Union, who are expected to lead the world toward it and no coalition of nations that demand it. The author believes that worldwide disarmament campaigns may add hope for future disarmament progress.

The article provides information on the meetings of Eighteen-Nation Disarmament Committee held in the U.S. for 1966. The meetings featured debates on disarmament items, and adopted disarmament resolutions. Some of the resolutions adopted by the general assembly include a treaty on the nonproliferation of nuclear weapons and urges all states to take all necessary steps conducive to the earliest conclusion to a treaty on the nonproliferation of nuclear weapons. Some of the issues discussed at the meeting include gases and bacteriological weapons, comprehensive test-ban committee treaty, and study report on nuclear weapons.

The article discusses some highlights about the conference of the United Nations on disarmament issues. The eight independent members of Eighteen-Nation Committee on Disarmament lead as sponsors and prime negotiators of resolutions. A quasi-disarmament measure on the declaration of legal principles governing the activities of states in outer space was approved unanimously by the assembly. Most discussions occurred on criteria for setting up atom-free zones while discussion was expected on measures to prevent surprise attacks.

The article focuses on the 7th United Nations General Assembly in Geneva, Switzerland. The conference highlights discussion on test-ban agreement, which was given first priority by the First Committee. The committee also addressed issues on general and complete disarmament, an atomic free Latin America, a convention to prohibit the use of nuclear weapons, and the peaceful uses of outer space. At the event, both the U.S. and the Soviet Union voted with unanimity on a majority of disarmament issues. The two countries abstained on the 37-nation test-ban resolution and voted for the resolutions on general and complete disarmament.

The article presents a discussion of the second world disarmament conference proposal through the Conference of the Committee on Disarmament (CCD) and the Strategic Arms Limitation Talks (SALT). There had been only one "world disarmament conference" that occurred in the 20th century, which dissolved as Hitler's Germany walked out of the Conference and started openly to rearm. The effort for a world disarmament conference languished when the heads of state met in Cairo in 1964. The 27th U.N. General Assembly could not authorize a Preparatory Committee due to the rising U.S. opposition to a world disarmament conference and continued Chinese opposition.

The article highlights the Conference of the Eighteen-Nation Committee on Disarmament (ENDC) sponsored by the United Nations in 1962. It attempted to establish a dialogue between the U.S. and the Soviet Union at the height of the Cold War. In addition to disarmament, the ENDC considered confidence-building measures and control of nuclear tests. ENDC had opened on March 14, 1962, on a foreign ministers level. Its test-ban subcommittee held fifty meetings and tried to find a formula for a comprehensive treaty, especially after the eight independent states offered a compromise in April 1962. Its committee of the whole held nine sessions to discuss collateral or partial disarmament measures.

Information about the several papers discussed at the European Federation Against Nuclear Arms which was held in Oxford, England on January 4-7, 1963 is presented. The delegates from the U.S. who are against nuclear weapons are reviewed. The conference tackled the pacifism issue and all non-aligned international organizations.

Information about several papers discussed at the Belgrade Conference in Belgrade, Serbia in 1961 is presented. The conference officially declared its refusal to create a third bloc which threatened other countries. It featured 25 prime ministers of non-aligned countries, presidents and princes who tried to sort out their ideas concerning war, peace, colonialism and neo-colonialism.

The article focuses on the development of a world disarmament conference, established at the twentieth United Nations General Assembly. Although there were 112 nations which unanimously voted in favor for the initiative, it can not occur earlier than January 1967 due to formidable challenges preventing it. During a debate by the United Nations Disarmament Commission, it was suggested that conference will be tackled as part of the five agenda items on disarmament. The debate also discussed the benefits of the conference including the initiative to draw military significant states and new force to disarmament discussions.

Information about several papers discussed during a world disarmament conference by the United Nations Disarmament Commission is presented. One of the two resolution passed during the session recommends that the United Nations General Assembly should provide urgent consideration to convening a world disarmament conference in which all countries would be invited.

Information about the topics discussed during Second Conference of Nonaligned Countries in Cairo, Egypt is presented. The conference talked about the differences in race, culture, history, geography, and social and economic systems. Delegates also pointed out the military blocs, great power alliances and pacts. It was suggested that an international treaty should be signed prohibiting the utilization of outer space for military purposes.

Information about disarmament and peace discussed during the World Congress for General Disarmament and Peace held in Moscow, Russia is presented. The event highlights discussion that allowed criticism on Soviet Union policy on nuclear warfare as well as issues on communism. It also includes details on the number of attendees, keynote speakers and delegates from participating countries.

The article highlights the Third World Conference against A- and H-bombs and for disarmament held in Tokyo, Japan on August 1957 sponsored by the Japan Council against Atomic and Hydrogen bombs. It is strictly nongovernmental and is called representative of all Japanese political parties and as a result the Japan Council incorporates considerable Communist and pro-Communist influence. Thus many Japanese scientists and religious leaders have little confidence in the Japan Council, however much they sympathize with its expressed purposes. This lack of confidence has spread abroad so that many responsible peace organizations in the United States and Western Europe hesitated to accept invitations to the Tokyo Conference.

Information about the Asian-African Conference that was held in Bandung, Indonesia in April 1955 is presented. The conference emphasized the significance of nuclear energy development for peaceful purposes for Asian and African countries. The conference also urged the speedy establishment of an International Atomic Energy Agency and recommended the Asian and African governments to take full advantage of the training and other facilities in the peaceful use of atomic energy.