Abstract Understanding barriers to organizational learning is central to understanding firm performance. We investigate the role of time delays between taking an action and observing the results in impeding learning. These delays, ubiquitous in real‐world settings, are relevant to tradeoffs between long term and short term. We build four learning heuristics, with different levels of complexity and rationality, and analyze their performance in a simple resource allocation task. All reliably converge to the optimal solution when there are no/short delays, and when those delays are correctly assessed. However, learning is slowed significantly when decision makers err in assessing the length of the delay. In many cases, the decision maker never finds the optimal solution, wandering in the action space or converging to a suboptimal allocation. Results are robust to the organization's level of rationality. The proposed heuristics can be applied to a range of problems for modeling learning from experience in the presence of delays. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract In a concurrent development process different releases of a software product overlap. Organizations involved in concurrent software development not only experience the dynamics common to single projects, but also face interactions between different releases of their product: they share resources among different stages of different projects, including customer support, they have a common code base and architecture that carries problems across releases, they use the same capabilities, and their market success in early releases impacts their resources in later ones. Drawing on two case studies we discuss some of the feedback processes central to concurrent software development and build a simple simulation model to analyze the resulting dynamics. This model sheds light on tipping dynamics, the nature of inter‐project feedback loops, and alternative resource allocation policies relevant to management of concurrent software development. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract Domestic violence is a major social problem. In the United States, the failure of communities and police departments to intervene resulted in a push to implement pro‐ and mandatory arrest policies for domestic violence. These policies have led to an unexpected increase in the number of victim arrests. Competing explanations have been offered. This paper describes the development of a system dynamics model of victim arrests. Results of model structure analysis suggest that these policies may have created or strengthened a crossover mechanism that shifts the risk of arrests in domestic violence cases from aggressors to victims. Model analysis also demonstrates how the changing role of cooperation between advocates and police can help explain the trends in victim arrests. Implications for research and policy are discussed. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract The authors advocate building a bridge between two systems approaches, namely system dynamics (SD) and the viable system model (VSM), which is the main exponent of organizational cybernetics (OC). Such a synthesis is aimed at opening a path towards a better capability of actors to deal with complex issues in both organizations and society. Given their respective strengths—modeling and simulation of content issues in the case of SD, and providing a viable organizational context in the case of OC—a combination of the two approaches is claimed to be potentially fertile. That argument gets twofold support. Firstly, the complementarity of SD and the VSM is cogently shown. Secondly, the authors refer to examples of synergy development through a combination of the two approaches. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract The purpose of this paper is to discuss the phenomenon of why some system dynamics projects fail to generate substantial impact in organizations—despite the fact that they are based on an apparently valid system dynamics model and are conducted by experts in the field. The approach followed in the paper is a conceptual discussion, extended by two short case studies. Findings are that the quality of the model and the expertise of the modeler are necessary but not sufficient requirements for organizational impact. Further research should concentrate on the detailed analysis of additional requirements. Practical implications are an increased embedding of system dynamics projects in organizational intervention architectures. The originality of the paper lies in its focus and discussion of failed projects that are invaluable sources for insight generation. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract In this paper a theoretical approach to group facilitation is introduced, based on the work of the so‐called Palo Alto school in communication and psychotherapy. This approach permits an analysis of group facilitation processes on the basis of several important principles that also inform system dynamics model building and simulation. On the basis of this analysis existing lists of appropriate facilitation skills and attitudes may be supplemented with three guidelines, leading to greater insight into the quality of the process of group model building and possible ways to evaluate that process. Ultimately, the growth and proliferation of system dynamics models and simulations depend on improvement of both process and content of modeling and simulation. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract I present a personal recollection of the history of system dynamics and observations about its present state. The article treats the history in two parts: first, my personal background and how all the threads came together to initiate the field of system dynamics; and second, the historical development of the cornerstone projects that shaped the field. These early works include industrial dynamics, urban dynamics, world dynamics, and the national economic model. The paper continues with an assessment of the present condition of the field. A companion paper (System Dynamics—The Next Fifty Years, also in this issue of System Dynamics Review), highlights challenges for the future. Copyright © 2007 Jay W. Forrester.

Abstract Chronic illness is the largest cause of death and source of health care costs in developed countries and a growing problem in developing countries. Here we build on past work in system dynamics and present a generic model of chronic illness, its treatment and prevention, applied to the U.S. population. The model explains the rising prevalence of illness and responses to it, including the treatment of complications and management activities designed to reduce complications. We show how progress in treatment and disease management has slowed since 1980 in the U.S., largely due to competition between health care payers and providers, resulting in price inflation and an unstable climate for health care investments. We demonstrate the impact of moving “upstream” by managing known risk factors to prevent illness onset, and moving even further upstream by addressing behaviors and living conditions linked to the initial development of these risk factors. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract Fifty years after its creation, I review the current status of the field of system dynamics and assess prospects for the next fifty. I focus on the challenges the field must face if it is to realize its potential.The first 50 years of system dynamics have established an introduction to the field. We have shown the importance of achieving a better understanding of complex systems in nature and human affairs. Now, the field is on a plateau ready to launch the next great thrust forward.We can better understand the present status of system dynamics by comparison to professions that have developed earlier. We are now at about the same state of advancement that engineering was when MIT first opened its doors in 1865, or that medicine was in the late 1800s when the Johns Hopkins School of Medicine was established.We have as much to learn yet about high‐order nonlinear feedback structures around us as those earlier professions have already learned about their fields in the last 150 years. Now is the time to plan how the next 50 years can start to close this huge knowledge gap.Like those early days in more mature professions, we do not yet have universities devoted to 4‐year and 6‐year programs in system dynamics. Like the older professions at their beginning, we do not yet have the equivalent of programs in science and biology in kindergarten through 12th grade education to prepare students for more advanced study at the university level. Nevertheless, there has been major progress in system dynamics during the last 50 years just as there had been in those older professions before they became formalized in advanced educational programs and before they were publicly recognized. Copyright © 2007 Jay W. Forrester.