Complex adaptive systems-of-systems are inherently multi-scale across several dimensions, including temporal, geographical, and organizational. We present a multi-model paradigm integrating a localized community-scale individual-based model (IBM) with a population scale system dynamics (SD) model to analyze long term results of potential policy interventions for obesity prevention. The IBM uses virtual agents embedded in a social network to simulate the spread of opinions relating to nutrition and physical activity (N&PA) behaviors such as dieting and exercise, and the effects of these opinions on individual behaviors. The network structure uses a mixture of scale-free and uniformly random connections to represent a social network of relationships and interactions within a local community. The N&PA related health behaviors of individuals change dynamically relative to endogenous influences within their social network and exogenous influences from industry-based advertising and public health-related educational policies. The outputs of the IBM, seen as changes in obesogenic (N&PA unhealthy) behavior prevalences, can be used as inputs to a SD model to calculate the resulting changes in mortality and morbidity over the ensuing decades. We analyze and compare effects of possible policy interventions, and illustrate a policy cocktail that addresses multiple aspects of the obesity problem, resulting in amplification of desirable results and a strong uncertainty reduction.
In order to cope with the vast range of ambiguous, multi-causal and multi-faceted potential causes for firm success, managers tend to look for critical success factors as a reduced number of essential factors that determine future business success. Although scholars have been serving this need for more than four decades, the insights derived from empirical research on critical success factors have low impact on strategy in practice. We take this phenomenon to discuss potential causes and propose to complement empirical methods with the dynamic feedback perspective of System Dynamics modeling.
A dynamic model of maintenance services is presented in this paper. The focus is on the service (i.e. value co-creation) perspective and the main purpose of the model is to facilitate the understanding of the added value of services. Determining the monetary value of services is important since the pricing of services is based on the value rather than on the cost. The modeled services vary by their complexity and their effects on the system. The model was built to be a communication tool for customer and the service provider to enable shared understanding of the system and the effects of different collaborative services.
In the aftermath of the expansive fiscal policy stimuli dealing with the consequences of the world financial crisis of 2007/2008 the public indebtedness around the world has increased dramatically. As a consequence the world-wide interest in policy measures to limit and reduce public debt has increased drastically. In Germany the parliament has altered the constitution which encompasses now a new article regarding a seemingly tight debt rule. In many member states of the EU and around a political discussion has started whether the German debt rule could serve as a guideline. This article explains the German rule and analyses its effects by employing system dynamics methods. The mainly qualitative analysis demonstrates that the German debt rule has important shortcomings and that there are severe side effects which have to be addressed by public policy.
The overall objective of this work is to improve the holistic value of energy development strategies by integrating management criteria for water availability, water quality, and ecosystem health into the energy system planning process. The Snake River Basin (SRB) in southern Idaho is used as a case study to show options for improving full economic utilization of aquatic resources given multiple scenarios such as changing climate, additional regulations, and increasing population. Through the incorporation of multiple management criteria, potential crosscutting solutions to energy and water issues in the SRB can be developed. The final result of this work will be a multi-criteria decision support tool usable by policy makers and researchers alike that will give insight into the behavior of the management criteria over time and will allow the user to experiment with a range of potential solutions. Because several basins in the arid west are dealing with similar water, energy, and ecosystem issues, the tool and conclusions will be transferrable to a wide range of locations and applications. This is a very large project to be completed in phases. This paper deals with interactions between the hydrologic system and water use at a basin level. Future work will include the interdependency between energy use and water use in these systems.
In this paper we demonstrate how the Major League Baseball (MLB) free agent compensation system (FA-CS), intended to achieve parity across MLB teams, has the unintended and adverse consequence of increasing inequality. The FA-CS compensates teams that release a Type A Free Agent by giving them a compensation pick the highest draft pick from the team that signs the free agent. The cost of each lost pick decreases as teams sign multiple Free Agents. This characteristic lowers the cost per Free Agents, when multiple Free Agents are signed. However, such benefits are solely accessible to teams that are relatively resource unconstrained, giving rise to an inequality-increasing positive feedback. To explore the importance of the FA-CS positive feedback, we develop a dynamic model of the flow of Type A Free Agents through their MLB career, including their maturation from draft picks, to minor league, to major league, to free agency, and finally to retirement. Additionally, we model teams free agent hiring process to understand free agent dispersion within the league. Isolating the FA-CS feedback from other scale effects and calibrating the model to MLB data we estimate the strength of this adverse inequality-increasing effect.
Throughout history some societies, including the Maya, Anazi and Easter Island, have collapsed, while others facing similar challenges, such as New Guinea and Japan, have succeeded. The Maya and New Guinea cases were taken from Jared Diamond's study, "Collapse," to create a system dynamics model capable of producing both the collapse and success behavior. The endogenous pressures described by Diamond were used to develop the feedback story. Policy interventions undertaken in by the society in the model were controlling family size, increasing farming intensity, reducing resource usage and composting. In the initial attempt the society enacted these interventions in response the cues of food shortages, perceived environmental degradation and falling crop yields (an indicator of soil quality). However, this version of the model was incapable of creating the success behavior mode, ruling out these cues as ones successful societies could have used. In version two, the society used a target land fraction occupied as its main cue and the gap between needed food production per acre and actual food production per acre as the drive to increase composting. This version was able to produce success behavior, which establishes these cues as possible cues a successful society could have used.