Online Content

1. Andersen, David F., "How Differences in Analytic Paradigms Can Lead to Differences in Policy Conclusions-- Two Case Studies"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
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System Modified Dtsi:
2020-01-02T18:34:24Z
Description:
This paper presents a conceptual framework for understanding the influence of alternative paradigms on policy conclusions. Two types of assumptions are associated with mathematical models--meta-assumptions or methodological priors and specification assumptions. Because two different paradigms must assume two different sets of methodological priors, the possibility exists that different problem definitions and hence policy conclusions may emerge from two parallel studies of the same area. In each of two cases presented here, a single problem area has been analyzed with two different methodologies. In each case, different policy conclusions have been reached as a result of the different methodological priors of the two paradigms. The first case involves two models used to analyze changes in retirement policies within the military enlisted system of the United States Armed Services. The second case involves two models used to analyze the determinants of equal educational opportunity in the United States. The dependence of the policy conclusions upon the analytic paradigm employed in a given study has important practical implications for the use of quantitative models in the analysis of social policy situations.

2. Bell, James A. with James F. Bell, "Views of Knowledge and System Dynamics: A Historical Perspective and Commentary"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/fj236j685?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:26Z
Description:
Views of knowledge contain methodological theories--theories of how knowledge progresses-- and epistemological theories-- theories about the nature of knowledge. The former serve four particularly important functions: providing formulas for the generation of knowledge, criteria for the legitimation of knowledge, reasons to suspect other ideas, and rules for the propogation of ideas.

3. Coyle, R.G., "A Method for Initial Formulation of System Dynamics Models"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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System Modified Dtsi:
2020-01-02T18:34:27Z
Description:
Even the experienced practitioner of system dynamics can encounter serious conceptual problems in getting started on a model, and is tempted to add more and more to his model. A technique – ‘list extension’ – is described which, from the purpose of the project and the importance of feedback loops, guides the evolution of the simplest adequate model. This model is expressed as an influence, or causal loop, diagram. The influence diagram should be tested to ensure that its structure contains the necessary elements of a dynamic model. If it fails the test attention is directed to the area of the system where further elucidation is needed. The techniques have been applied in many practical cases and have been found to give useful results and to increase the efficiency of the modelling process.

4. Dangerfield, B. C., "A System Dynamics Model of the U.K. Consumer Durables Manufacturing Industry: Some Preliminary Results"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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System Modified Dtsi:
2020-01-02T18:34:28Z
Description:
The paper describes a system dynamics model of the consumer durables manufacturing industry in the United Kingdom. The model purpose is to analyse the causes and effects of cyclical fluctuations in the industry with a view to encouraging government or operational policies that might improve industry stability. The paper extensively examines the consumer durables industry and explains the model in detail, each equation being accompanied by an account of its construction. The results of the simulation experiments conducted on the model using various test inputs are described. The paper appraises the technique of spectral analysis, which has served as one means of assessing model validity. The model, once validated, should form part of a larger model which will also represent the steel stockholding and steel manufacturing industries. Work on the larger model is in progress.

5. Graham, Alan K., "Parameter Formulation and Estimation in System Dynamics Model"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/ft8498095?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:29Z
Description:
The purpose of this paper is to convey the techniques and considerations normally involved in formulating and estimating parameters in system dynamics models. Ideally, model equations should be formulated so that the associated parameters each describe some unique observable characteristic of the real system. Thereby, translating observations and measurements below the level of aggregation of model structure (estimation from disaggregate data) into specific parameter values becomes very straightforward. Fewer assumptions about the structure of the system are needed than if the parameters were set by equation estimation or model estimation from data at the level of aggregation of model structure. Making additional assumptions provides more opportunities for systematic errors to creep into the parameter-setting process. Rather than using data at or above the level of aggregation of model structure to set parameters, such information might better be reserved for validity testing. When such data are not already used to set parameter values, the validity tests become simpler and depend upon fewer assumptions.Parameters need only be set accurately enough to allow the model to fulfill its purpose. One time-saving research strategy is to determine, by using only roughly-set parameters at first, how accurately the parameters must be set before investing time and effort in setting them accurately. Then, sensitivity testing can identify the relatively small number of parameters whose values significantly alter the model behavior or response to policy changes. The model can then be reformulated, the policies redesigned, or the sensitive parameters reset by more elaborate and hopefully more accurate techniques.

6. Hamilton, Margaret S., "Estimating Lengths and Orders of Delays in System Dynamics Models"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/pv63gh69w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:30Z
Description:
Delays are a ubiquitous feature of dynamic systems; they are present at every stage of an action. An understanding of delays is necessary if policy makers are to foresee the consequences of their actions. It is often not sufficient to rely on “expert” opinion to tell how long it will take for the repercussions of an action to be complete, because even the “experts” can seriously underestimated delay times. It is, therefore, important to have systematic methods of estimating the length of delays in system dynamics models. The time structure of delays is also important.Whether a delay is destabilizing or stabilizing will depend on whether the repercussions are concentrated or dispersed, as well as whether the time lag is long or short. Systematic methods of estimating the orders of delays are, therefore, also useful. This paper presents five statistical methods that can be used to estimate lengths and orders of delays in system dynamics models. The presentation contains a discussion of when each method is applicable and what problems may be encountered in using it. Empirical results from applying two of the methods are discussed. The empirical studies respectively involve the problem of estimating the delay between changes in export prices and changes in export market shares and the problem of estimating the delay between capital appropriations and capital expenditures.The paper also offers guidelines for choosing an estimation technique and discusses validation of the estimates obtained.

7. Krallmann, Hermann, "The Integration of Alternative Modelling with Dynamo"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/sb397t15t?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:31Z
Description:
Often system dynamics, and particularly the DYNAMO- language, is attacked for not integrating other modelling approaches into the field. This investigation offers alternatives that will hopefully stand up against the critics. The first part of this paper concerns the integration of external functions into system dynamics models. Modifications of the DYNAMO simulation language and of the DYNAMO compiler are explained, and conceptional questions about the integration are discussed. By means of examples of LP programs and statistical methods, the paper shows the philosophical improvements entailed by the system dynamics method.The same criteria are applied in the second part of this paper to the model-method integration of a system dynamics model with an input-output method, considered to be representative of a complete economic structure.The last part of the paper explains the integration of system dynamics model into the higher program structure of an optimizing feedback loop. The best combination of input vector parameters is calculated in the feedback loop at any time so that the output vector follows a predetermined objective function. The overall paper contents demonstrate the flexibility of the system dynamics method.

8. Lied, Finn, "Social Difficulties Versus Social Problems"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/34850069t?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:32Z
Description:
The opening address at the 1976 International Conference on System Dynamics points out that today's social ills are diffuse difficulties rather than clear-cut problems. Remedial action must start with attempts to clarify the problem, and develop alternative comprehensive strategies that consider a wide segment of society and also the long-term future in an open minded fashion. System Dynamics may serve as a tool for broad policy analysis of this kind.

9. Low, Gilbert W., "The Principle of Conservation and the Multiplier-Accelerator Theory of Business Cycles"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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System Modified Dtsi:
2020-01-02T18:34:33Z
Description:
The principle of conservation states that physical quantities are confined to their own identifiable channels and can enter, circulate within, or depart from a system only by explicit processes. This paper applies the conservation principle to an analysis of the multiplier-accelerator theory of business cycles. Section I describes and critiques a well-known model of the multiplier-accelerator interaction. By ignoring accumulations of inventory and fixed capital investment, the model fails to observe the conservation of important physical flows. Section II proposes a system dynamics model that incorporates the multiplier and accelerator processes within a closed, conserved-flow framework. Section III uses computer simulation to portray the impact of conservation on the multiplier-accelerator interaction. Simulations of the system dynamics model reveal plausible long-term cycles, rather than the short-term fluctuation associated with traditional multiplier-accelerator models. At the end of Section III, the model is modified to account explicitly for labor, as well as capital, in the production process. This revised model produces both short-term and long-term oscillation when submitted to a noise input. The short-term oscillations, averaging about 5 years, reflect the attempt to adjust inventories by varying the labor input to production. The longer fluctuations in capital stock, averaging 19 years, reflect the management of investment in fixed capital. In all of the tests, the incorporation of conserved flows considerably reduces the sensitivity of system behavior to changes in parameter values. The simulations provide theoretical evidence for divorcing short-term business cycles from the interaction of the multiplier and accelerator.

10. Mass, Nathaniel J., "Stock and Flow Variables and the Dynamics of Supply and Demand"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/pc28b212p?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:34Z
Description:
This paper contrast two viewpoints for analyzing the concepts of supply and demand. The first viewpoint, which dominates most economic thinking, treats supply and demand as rates of flow. For example, supply in economic models tends to be measured by a rate of production, while demand is measured by a flow of consumption or purchases. The second viewpoint sees supply and demand primarily as stock variables or integrations. According to this viewpoint, for example, supply would be measure by the available inventory of a commodity while demand would be measured by a backlog of unfilled orders. The central point of the paper is that stock-variable concepts of supply and demand must be incorporated explicitly in economic models in order to capture the full range of disequilibrium behaviour characteristics of real socio-economic systems. More specifically, the paper shows that consideration of stock-variable measures of supply and demand is necessary to describe the price- and quantity-adjustment mechanisms linking supply and demand; to analyze properly the stability characteristics of an economic systems; to analyze short-run and long-run disequilibrium behaviour; and to assess the desirability of economic policies intended to influence such disequilibrium modes behaviour as economic growth and fluctuation.

11. Mass, Nathaniel J. with Peter M. Senge, "Alternative Tests for the Selection of Model Variables"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/j6731m78w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:35Z
Description:
This paper contrasts two approaches to testing the importance of model variables: single-equation statistical tests and model-behavior tests. The paper demonstrates that, both theoretically and operationally, tests which analyze the impact of individual variables on model behavior are better suited to the task of selecting model variables. Conversely, the statistical tests should not be viewed as tests of model specification per se, but as tests of a particular type of data usefulness. When viewed as tests of data usefulness, the statistical tests have a clear, albeit quite narrow, role in model validation: they warn the modeler when available data do not permit accurate estimation of model parameter. However, as a detailed example illustrates, a model relationship may be difficult to estimate yet extremely important for overall model behavior.

12. Meadows, Donella H., "The Unavoidable A Priori"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/8w32rq04w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:36Z
Description:
This paper is a summary of the major assumptions underlying the field of computer modeling and the specific assumptions that differentiate four modeling methods used to represent social systems: system dynamics, econometrics, input-output analysis, and optimization. The primary conclusions are: 1. Each modeling method is based on a set of techniques and priors that suit it well to some sorts of policy problems and poorly to others. 2. Misunderstandings between different kinds of modelers and between modelers and clients often arise from failures to recognize these implicit priors and the various strengths and weaknesses of the various modeling schools. 3. Some modeling schools, especially system dynamics and econometrics, are based on such different basic world views and assumptions about the nature of human knowledge that communication from one school to another is almost impossible.

13. Nilsson, Jan-Evert, "A Framework for Understanding Social Phenomena"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/1g05fw27q?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:37Z
Description:
In this report we discuss our possibilities to attain insight about social phenomena. In the first part of the report we argue the nature of social phenomena is different from natural phenomena. Therefore there is a danger connected with the fact that social science for so long time has been dominated by techniques and goals which were successfully developed for the purpose of natural science. In the second part of the report we identify and discuss four essential problems in the study of social phenomena. The problems are: (a) the definition problem, (b) the issue of limitation, (c) the problem of causality and (d) the problem of stability. In the last part of the report we discuss in what way social phenomena can be understood. Six conditions for a successful paradigm in social science are presented and we can conclude that used in a proper way System Dynamics can be one paradigm that fulfill these conditions.

14. Phillips, W. G. B., "Monte Carlo Tests of Conclusion Robustness"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/hm50v9152?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:38Z
Description:
Conclusions derived from world models have little value if they do no include an estimate of the uncertainty associated with the outputs. This paper describes the System Analysis Research Unit World Model and gives an account of the application of Monte Carlo techniques to testing the model. Samples of uncertain data encoded in probability densities are used as input for model runs. The model output is analysed statistically and the contribution to total uncertainty by the variance of the inputs is determined. The output is also to be additive over a limited range. Due to the strong negative feedback loops in the model, the model usually attenuates any variation in inputs. The cost of Monte Carlo methods is justified by the quality of the results obtained.

15. Rahn, R. Joel, "Delays and Aggregation in System Dynamics Model"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/pz50hd740?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:39Z
Description:
This paper focuses on the aggregation that is implicit in the use of distributed delays in dynamic models. The aggregation process relates the continuous time-dependent response of a delay structure to the underlying distribution of delay times of the disaggregated events which constitute the delay. The discussion covers in particular the special case of exponential delays used in system dynamics models.

16. Randers, Jørgen, "System Dynamics: A Tool for Broad Policy Analysis"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/hh63td14j?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:40Z
Description:
Industrialized societies are presently characterized by rapid change, strong interactions and an abundance of new phenomena. To increase the likelihood of policies having the intended effects, there is a need for policy analysis with a broader perspective and longer time horizon. The main task in such broad policy analysis should be to integrate the vast amount of available information into a useful conceptual structure of the problem area. System Dynamics (SD) –relying heavily on descriptive information for a data base, on a theory of the structure of social systems for theory formation, and on computer simulation for relating structure to behaviour—offers one method of attaining such broad policy analysis. This paper reviews the historical development of the field and examines the major system dynamics literature. The impatient questions of “what is?”, “why does one do?”, “when should one do?”, and “how does one do SD?” are all answered in summary fashion. Within the system dynamics profession, intense conflicts abound as to what constitutes “proper procedure” for the policy analysis process, particularly concerning model conceptualization and testing. Much disagreement arises from implicit differences in modeling objectives. Explicit recognition of objectives and procedures could reduce much of the conflict.

17. Randers, Jørgen, "A System Dynamics Study of the Transition from Ample to Scarce Wood Resources"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
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/downloads/ng452186v?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:41Z
Description:
The Scandinavian countries are approaching full utilization of the regrowth in domestic forests, and the forest industry is facing a period of much slower expansion in volume than in the past. Slower growth implies problems for the industry, forestry, and society at large. The “transition” from ample to scarce wood resources could take several forms, depending on actions taken both inside and outside the forest sector. A system dynamics simulation model has been constructed to describe different possible transition paths, and to highlight potential problems. The model purpose is not to predict what will actually happen in the future, but to describe possible futures in an internally consistent way. Such insights about the consequences of various management strategies are useful to interest groups as a basis for discussing how to reach their goals. Within the industry, there is a tendency toward temporary overexpansion of capacity. The forest sector's ability to survive under slow growth conditions could be enhanced by technological and organizational remedies. The necessary remedies will be less traumatic the earlier one accepts and acts upon the problems of finite wood supply.

18. Randers, Jorgen, "A Framework for Discussion of Model Conceptualization"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/34850070k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:42Z
Description:
The process of attaining a useful model embraces the conceptualization, formulation, and testing stages. This paper argues that effective conceptualization can be achieved through a dynamic hypothesis (that is, a chosen time development of interest and hypotheses about the underlying mechanisms). The resulting rough, conceptual model should then be improved gradually through a recursive procedure where the model is tested, redesigned and tested again, in as many ways as possible and as long as is feasible. The paper attempts to structure the hazy topic of model construction by defining a number of terms and presents lists of dysfunctional tendencies in and guidelines for model construction.

19. Rechenmann, F., "Top-Down Systems Analysis and Modeling"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/p2677d06r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:43Z
Description:
According to an implicit “start simple” principle widely accepted by system dynamics practioners, model’s complexity must be progressively increased during the modeling process. How this increase in complexity should come about has yet to be explained. In this paper, two strategies are discussed and evaluated. Since a top-down strategy starts with a high level of aggregation but includes in the model all the main variables since the first formulation, it is to be preferred to a bottom-up scheme. Moreover, the top-down strategy ensures the global coherence of the model at any stage of its conception and appears to be much more consistent with the system dynamics philosophy. This paper emphasizes the need for an adequate computer modeling language and briefly describes a first attempt. The main property of such a language is to allow a hierarchical description of models, where any composing unit can be altered without the need for a complete recompiling of the whole.

20. Robinson, Jennifer M., "Managerial Sketches of the Steps of Modeling"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/5d86ph39d?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:44Z
Description:
Observations of modeling efforts suggest that many models fail for managerial reasons. This paper is based on the hypothesis that 1) managerial failures occur because various facets of the modeling process are inherently hard to manage, and 2) that deliberate management can reduce or eliminate many common problems. The hypothesis is pursued by breaking the modeling procedure into a series of steps, sketching what typically does but should not happen at each of them, and putting forth some thoughts about what can be done to avoid the normal pitfalls. Particular attention is paid to mundane variables such as time allocations and finances and attitudes and emotional considerations. In general, when modeling study is not deliberately managed, the construction phase preempts the bulk of time and resources to the detriment of planning, conceptualization, testing, documentation, and client-modeler interaction. This phenomenon appears to be caused, in part, by an over-emphasis on the “harder”, more technical work of construction; by difficulty justifying work that produces no direct, tangible product; and by mental resistance to testing.

21. Runge, Dale, "Labor-Market Dynamics"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/0z709d205?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:45Z
Description:
This paper presents a system dynamics model of worker mobility and wage determination in a multi-sector economy. The paper reviews the background and structure of the model, illustrates the model validation process, and sheds light on the dynamics of the labor market.

22. Runge, Dale, "The Reference Mode as a Guide to Transparent Causal Structure"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/6395wr729?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:46Z
Description:
This paper establishes the importance and usefulness of a well-defined reference mode as a guide to developing transparent causal structures for system dynamics models. The importance of a transparent causal structure is two-fold: it enhances understanding the model dynamics, and it facilitates communicating to others the model and the insights derived from model simulations. The paper offers a fundamental guideline for selecting transparent causal structures the following: strive for as highly-aggregated and as simple a structure that will generate the dynamics of interest. Ability to follow the guideline depends on a well-defined reference mode, which in turn requires a clear model purpose. To illustrate how a well-defined reference mode can guide the selection of a transparent causal structure, the paper traces the development of a model of the labor market. First, the model purpose is described. Next, the evolution of the basic causal structure is discussed, utilizing the reference mode embodied in the model purpose to select a transparent structure. Finally, the causal influences on model rates of flow are highlighted. To establish the suitability of the selected structure, the paper then summarizes the results of model tests. As the paper shows, the relatively transparent causal structure chosen for the model appears capable of providing insight into the real-world labor market, and of enhancing labor-market policy analysis.

23. Sharp, J.A., "Sensitivity Analysis Methods for System Dynamics Models"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/w9505j27m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:47Z
Description:
System Dynamics (SD) may be viewed as a process of designing ROBUST systems. The concept of ROBUSTNESS leads to a need for analyzing the effects on SD models of both parameter changes and stochastic inputs. It is demonstrated that the effects of large parameter changes can be measured by the use of hill climbing techniques given efficient computation. The paper describes the traditional ways of assessing sensitivities in SD models, together with methods based on perturbation techniques which unify the parameter and stochastic sensitivity problems. The computational characteristics of the various methods are analysed and the factors that affect their computational efficiency are discussed.The paper discusses the results of experiments to determine the accuracy and speed of the various methods on a 7 state variable, 16 parameter model and on a 70 state variable, 160 parameter model derived from it. The perturbation methods yield acceptable accuracy and for the models described reduce computer time by a factor of between 9 and 25. Compiler changes discussed in the paper would make sensitivity analysis easier and quicker and would improve techniques elsewhere in System Dynamic.

24. Stanley-Miller, John, "Guidelines for Model Refinement"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/qf85nv47g?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:48Z
Description:
Model building standards within the field of system dynamics are still evolving. This paper offers some general guidelines for development and presentation of refined models. Model refinement, the core of the modeling process, encompasses incremental structural and/or parametric changes to existing models. Development and presentation of refined models are enhanced through comparison of original and refined model behaviour and through comparison of policy response. Model comparison aids the modeler in identifying misspecification of new structure. In addition, presentation of comparison results assists the reader in evaluating the merits of the refined as compared to the original model, and helps to insure that the builder and user of the refined model is familiar with original model assumptions.

25. Stenberg, Lennart, "A Modeling Procedure for the Public Policy Scene. Experiences from a System Dynamics Study of the Scandinavian Forestry and Forest Industry"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/q524k6795?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:49Z
Description:
The basic assumption of this paper is that system dynamics in its original form was developed to suit policy-making in small organizations and that application of system dynamics in the field of public policy must be accompanied by change in research methodology and organization. To support this view, the paper describes experiences from a study of the Scandinavian forestry and forest industry.The model building process, interaction with decision-makers, and the organization of empirical research are analyzed separately. Based on the analysis a procedure for using system dynamics in public policy analysis is recommended. In the recommended procedure a reference group representing various client groups serves a source of qualitative information and as a channel for implementation. The need to keep model building well focused is stressed. Parallel studies of historical development on the micro- and the macro-level are suggested as a means to speed up modeling. It is finally recommended that the major results from the analysis are presented in a non-technical report.

26. Tank-Nielsen, Carsten, "Sensitivity Analysis in System Dynamics"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/jm215699w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:51Z
Description:
This paper describes some of the central, non-procedural aspects of sensitivity analysis in system dynamics.First section focuses on the objectives of sensitivity analysis in this particular field of modeling.The second section concentrates on the types of model change involved, with emphasis on changes in model structure and parameters.The third section discusses the interpretation of model response to changes. The central questions are how the sensitivity is judged and by whom.The final section discusses the parts in the modeling process entailing sensitivity testing.Overall the paper asserts a more comprehensive role for sensitivity analysis than seems to be commonly accepted among model builders and model users. The subjectivity and individuality of sensitivity analysis is also emphasized.

27. Thissen, Wil, "Guidelines and Tools for Understanding Dynamic Models"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/x059cr357?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:52Z
Description:
Starting from the aims and difficulties of social systems modeling this paper argues that a good understanding of dynamic mathematical models is indispensible. The author’s background, and its relation to System Dynamics is elucidated, and a number of definitions are given of concepts and terms that will be employed. A set of general guidelines, and a list of strategies and tools for understanding follow. Most of the methods presented have been applied successfully in an extensive study of the World Models by Forrester and Meadows et al., and are commonly used in systems and control engineering. The main emphasis is on techniques are points of view that are generally unknown to researchers and practicians in the non-technical disciplines.

28. Weil , Henry Birdseye, "Achieving Implement Results from System Dynamics Projects: The Evolution of an Approach"

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/9880w826z?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:53Z
Description:
This paper documents a series of lessons that the author and his colleagues have learned about how to achieve implemented results from system dynamics projects. Through a series of three case studies, the paper illustrates the evolution of their approach to implementation over the period of 1966 to 1975. These case studies focus on: client involvement in projects; the process of model development; the nature of the models developed; and the end of the projects. The paper draws upon the case studies and earlier writing on the subject by Roberts to generalize about the factors that are most critical in achieving successful implementation. These factors include: the sharpness of the project’s problem focus; the urgency of the problem addressed; the organizational position of the clients; the degree and nature of client involvement; the size of the model developed; the demonstrable validity of the model and the nature of the project’s end-products.

29. Wenstop, Fred, "How Can One Explicitly Represent the Fuzzy Nature of Social Causal Relations in Formal Models? Fuzzy Set Simulation Models

Type:
Document
Date Created:
1976
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 7f4e0cd9dcbf7a3743e13c4911e77bc2, and dbb17ec8affa7ecbcd419a760cb61093
Thumbnail Path Ss:
/downloads/6d570f006?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:54Z
Description:
This paper introduces and discusses the concept of verbally formulated simulation models. Such models can operate with linguistic values as ‘high’, ‘rather high’, ‘low’ and ‘not low’, etc. as inputs. The output will be similarly verbally formulated. The stimulation procedure is based on a fuzzy set-theoretical semantical model of a fragment of English language, which converts verbal expressions into numerical quantities. The paper applies one particular semantical model in a simulation example. Verbal models may be more believable, or significant, than conventional system dynamic models, in that they adequately represent the fuzzy knowledge of the system which is modeled. The cost of this significance is loss of precision in model output. Verbal models are also easier to test for sensitivity to parameter-, state- and input values than traditional models. Therefore, a comprehensive understanding of the model’s behavior patterns is more readily obtained. The realm of successful applications of verbal models seems, however, to be restricted to systems with variables which are not physically measurable, but whose values are only available through human intuition. Finally, verbal models may successfully be incorporated in conventional system dynamic models if technically feasible. Such a prosedure would allow for an adequate handling of non-quantifiable data.

30. Andersen, David F., "Why Mathematical Models of Public Policy Issues Often Don’t Work"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/r781x092k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:55Z
Description:
The central premise of this study is that complex models of social processes often fail to provide direct and useful evidence for policy makers because, of necessity, complex models are based upon five distinct classes of assumptions. At least two of these five classes of assumptions are based upon a priori or theoretical arguments rather than strict empirical arguments. Because of their inherent speculative nature (at least in part), complex models produce forecasts that are not admissible as evidence in an essentially political debate.

31. Beijdorff, Roland O. with Danny R. Davies and John Q. Rade, "An Analysis of the Dutch Paper Recycling System"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/1c18f0563?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:56Z
Description:
About five years ago a semi-governmental firm, the VAM (Vuil Afovoer Maatschappij) formulated plans to extend their efforts to convert domestic waste to compost to a real recycling industry. The idea was to install equipment to extract secondary paper pulp from domestic waste and sell it to paper and board industry. The Union of Old Paper Merchants opposed strongly: abundancy of low grade secondary paper pulp could ruin the old paper market and times were bad just after the oil crisis. A study was started to investigate possible consequences of the VAM plans. In the four following years a System Dynamics model was built to show the most important mechanisms of the problem.

32. Bencosme, Arturo J., "A System Dynamics Approach to Evaluating Transportation System Alternatives within a Development Planning Context with Reference to the Venezuelan Case"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/tm70nd66n?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:57Z
Description:
This paper describes a System Dynamics approach to the problem of linking national and regional transportation to other components of national development plans. A framework of interactions among social, economic, and transportation variables is constructed based on the proposed approach. Such a framework facilitates the analysis of the reciprocal impacts of transportation infrastructure and the socio-economic environment, thus providing an important input to the process of transportation policy making for development. Specific references are made to Venezuela, where a serious effort is being made to explicitly incorporate a transportation strategy into the national development plan.

33. Bienert, Kurt, "Dynamic Capacity and Location Planning of Physical Distribution Systems"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/0p096q69x?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:58Z
Description:
The model system is an approach to solve the dynamic multilocation warehouse (or plant) sizing problem by integrating different models and methods: (1) A simulation model of System Dynamics type for analyzing effects of different locations and capacities on demand, cost, and operating results; (2) An Integer Programming model for determining warehouse configurations, i.e. effective locations, and capacities. The model system has been applied to an important German wholesale distributor of pharmaceuticals. It has been used for analyzing the firm’s distribution system, and working out proposals in order to improve it.

34. Boyce, Stephen G., "Multiple-Use of Renewable Resources is Enhanced with System Dynamics Methods"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/g445cx744?file=thumbnail
System Modified Dtsi:
2020-01-02T18:34:59Z
Description:
A study of the multiple-use task produces a method for integrating quantitative and subjective information to enhance decision-making about the multiple use of renewable resources. Methods of resolving conflicts and applying system dynamics methods are given.

35. Braden, Charles H., "System Dynamics and Input-Output Analysis"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/vm40z873h?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:00Z
Description:
Input-output analysis for an “open” system relates production rates for various sectors of an economy to stipulated final demands. However, it is well known that the conventional dynamic analysis usually does not yield results which approach smoothly to those of the static analysis. In this work, the dynamic analysis is cast into the form of a system dynamics model. A modification of the rule which governs sector production rates is introduced so that stable results are obtained which do approach those of the usual static input-output analysis. The system equations are further modified to incorporate time-lagged stock indices and damping in the production rate rule. Prices are handled throughout as in conventional input-output analysis.

36. Bresser, A. H. M. with W. K. Pluym and W. I. Wils, "Optimization and Simulation in Planning of Systems of Drinking Water Supply: A Dutch Experience"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/r207v667s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:01Z
Description:
In the simulation model the development of the drinking water supply system of South Holland is simulated for the next thirty years given a policy strategy, a certain demand of drinking and subpotable water and some scenario assumptions like discount rate, water quality standards, increase of energy prices. An alternative policy strategy generates an alternative development over time of the supply system.

37. Breton, Louis, "MEDOC Model: A SD Approach to the Red Wine Market"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/nc581519z?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:02Z
Description:
To introduce system dynamics approach into interprofessional organization to built a model about agricultural market is not so original. That’s more interesting is the use of system dynamic to define what information system must be not only designed but scheduled to regulate the market. Since July 1979, MEDOC gives some useful informations to people who have the difficult challenge to follow the Bordeaux wines market.

38. Cavana, R.Y., "A Case Study in Problem Definition for a System Dynamics Model"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/3j333k98b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:03Z
Description:
This paper contributes to the discussion of academic training requirements for System Dynamics modelers. In particular, it suggest that training in Strategic Management can provide the System Dynamics modeler with some essential complementary tools and a “top management perspective” (or systems viewpoint), which is needed to define problems of real managerial interest. To illustrate these points, the author describes his experiences in defining a problem for system dynamics modeling. The future prospects for the New Zealand Forestry Sector, and the New Zealand Forest Service, are described and the problem for modeling is presented.

39. Chen, Fiona with David Andersen and Tanette Nguyen, "The Impacts of Implementing a Cost-of-Education Index on the Equalization of Education Expenditures per Pupil"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/9593vc50s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:04Z
Description:
In this paper, a pilot system dynamics simulation model, EDFIN1, is used to forecast the impacts of a cost-of-education index (COEI) on patterns of per pupil expenditures across various types of local school districts. Originally designed to compensate more fully those districts that incurred greater costs in the purchasing of educational inputs (i.e., higher teacher salaries or greater need for transportation), COEI adjustments are seen also to have direct impacts on the relative equity of per pupil expenditures across the states as a whole.

40. Chourci, Nazli, "Dynamic Adjustments and Change in the World Oil Market"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/47429t61j?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:05Z
Description:
The world oil market is undergoing substantial changes, in terms of overall structure, number of key participants, and market adjustment mechanisms. These changes will influence both price determination as well as critical decisions pertaining to the production capacity utilization.

41. Clark, Thomas D. Jr., "The United States Arms Transfer Process and Policy: A Systems Dynamic Approach"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/st74d885r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:06Z
Description:
This paper deals with the structure of the system of arms transfers by the United States to the rest of the world. Arms transfers play a significant role in the political, economic, and military affairs of most countries. Because of the diversity of opinion about the necessity for transfers and their true effect, a single policy concerning arms movement has been impossible to devise. This research is the first step in providing a model that can be used to study the effects of transfers and to evaluate policy concerning arms movement.

42. Clauset, Karl H. Jr. with Alan K. Gaynor, "The Dynamics of Effective and Ineffective Schooling: A System Dynamics Policy Study"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/z316qk741?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:07Z
Description:
In large numbers of U.S. urban elementary schools, there is a multiplier effect which operates to reinforce high achievement for initially high-achievers, average achievement for initially average-achievers, and failure for initially low-achievers. This problem is aggravated by the fact that initial levels and perceptions of achievement are systematically related to social class. In part, poor children enter school with less readiness for reading. Evidence also suggests that, actual achievement aside, teachers tend to perceive lower class children as low-achievers simply because they exhibit lower-class family, dress, and behavioral characteristics. In contrast, there are a relatively small number of “lighthouse” schools spread through out the country in which students, often minority and/or poor, achieve far better than home or SES variables would predict.

43. Coyle, R. G., "Survey of Business Schools Teaching System Dynamics"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/s46560860?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:08Z

44. Dangerfield, Brian C., "System Dynamics as a Potential Aid to Capacity Planning in the U.K. Steel Industry"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/0c484271b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:09Z
Description:
Any firm or industry which experiences marked cyclical fluctuations in both output and demand can provide a testimony of the damaging effects such oscillations have on profitability. Perhaps none more so than the British Steel Corporation (B.S.C.) whose record in this respect is rather poor. For such industries, therefore, any methods which management science can provide as a means of analysis of the causes and effects of such cycles are to be welcomed. It is suggested in this paper that system dynamics provides an important framework for analyzing the causes of cyclical behaviour in economic systems and that it is this area of application which possesses the greatest chance for successful demonstrations of its use. It is probably for this reason that work using the methods of system dynamics has concentrated, in Gt Britain, on economic systems.

45. Davies, D. R. with R. E. H. M. Smits, R. Tweehuysen and W. Wiis, "Staffgroup Strategic Surveys TNO: Mobility of Researchers in the Netherlands"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/bn999r37k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:10Z
Description:
At the beginning of the seventies, grave concern existed over low mobility of researchers due to the stagnation in growth in the research capacity available. Through a strong expansion in research capacity prior to this condition of stagnation, the age of researchers was relatively low. It was feared that the small natural turnover (as a result of a low average age) together with the low mobility would lead to a collective aging of the research corps itself. This aging factor was considered to be a threat to research as a whole since it could lead to mental fixation and loss of creativity. In addition to this, the expectations for making a career and the employment possibilities open to the then recently graduated university students had strongly decreased. This situation resulted in a loss of talent for research groups, and it was feared that there would be a decline in the motivation and development possibilities for researchers. The developments briefly described here formed no phenomena exclusive to the Netherlands but also made their appearances in substantially all of the western countries.

46. Day, Richard H., "Complex Behavior in System Dynamics Models"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/x633fh98s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:11Z
Description:
Nonlinear differential equation systems of the kind used in system dynamics are capable of exhibiting highly irregular, erratic, turbulent or “chaotic” behavior. Conditions for the existence of this phenomenon are discussed and their application in dynamic socio-economic modeling explored. In particular, irregularities in economic cycles might be explained by nonlinear feedback effects in contrast to the usual “random shock” model. Dynamo simulations are used to illustrate the basic concepts involved. The view, often emphasized by Forrester, that policy should not be based on level predictions but should focus on regulating qualitative modes would seem to be strongly supported. The positive economics position associated with Friedman that theories should be judged on their predictive performance would now appear to be too restrictive. Instead, the system dynamics view that the plausibility of model assumptions should be the main basis for establishing theory credibility is strongly reinforced.

47. DeGreene, Kenyon B., "Is System Dynamics Theory Complete? –Extensions and Interfaces"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/nc581520q?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:12Z
Description:
System Dynamics consists of a body of theory, philosophy, methodology, policy-related applications, and experience. Basic to system dynamics is the theory of the semi-closed, fully closed-loop system in which the feedback loop is the principal construct. In the 20 years of its existence, major emphasis has been placed on the methodology of model-building, on applications, and on philosophical debates involving alternative approaches, particularly the static econometric approach. Experience has produced improvements in the original theory. However, feedback loops are not the only constructs for dynamic theory-building, and cybernetic, self-regulating systems are not the only kinds of living systems, nor is the cybernetic perspective invariably the only or most appropriate perspective over the life history of a particular system. The processes of self-organization and the emergence of new structure deserve equal attention in the evolution of systems. This paper briefly reviews the history of system dynamics. An analysis is then made of present system dynamics theory. This is followed by summaries of three field theories—of critical phenomena, catastrophe theory, and disruptive structures—and attempts at synthesizing these theories and system dynamics. Then ways of enriching existing system dynamics models with fuller use of knowledge from behavioral/social science and sociotechnical systems, with particular relevance to the National Model, are discussed. The paper concludes with an identification of three immediate next steps in research.

48. Dobrowolski, G. with T. Rys and M. Zebrowski, "Analysis of SD Models Based on Experiments with Families of Trajectories"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/8049gp659?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:13Z
Description:
There is unquestionable need for sound and disciplined methodology of experimenting with SD models. A number of valuable papers shows various ways utilizing sensitivity analysis, programming of experiments and other approaches. But should we not attack the problem more fundamentally before getting into more specific and costly analysis? We would like propose a different kind of approach, it is analysis of SD models based on experiments with families of trajectories.

49. Drew, Donald R., "National Reconstruction and Development Model of Lebanon"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/cj82ks13b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:14Z
Description:
Lebanon, the country is new; Lebanese society is ancient.  Lebanon’s current geographic frontiers and political institutions were defined in the Constitution of 1926 and, except for slight modifications introduced on the eve of Lebanon’s independence 1943, remain in effect. The social and cultural characteristics of Lebanese society have their origins in the Phoenician, Greco-Roman, Arab, and Ottoman civilizations. The Lebanese state, with an area of ten thousand square kilometers, and Lebanese society with a resident population of three million persons (and almost an equal number of expatriates), have a significance in the Middle East and, indeed worldwide, out of proportion to their size, owing to their role as a vital link between East and West.

50. Fey, Willard, "The Dynamics of System Dynamics"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/th83mh04d?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:15Z
Description:
After twenty-five years of development and some notable achievements the field of System Dynamics is not as large, well-known, respected and influential as it should be based on the breadth and power of its principles and the need of industry and society for dynamic analysis of this kind. It is suggested that System Dynamics’ methods be used to analyze the growth of the field and improve its development. This paper initiates the self-analysis by presenting a review of performance and preliminary model structure for the field to encourage constructive criticism and to facilitate understanding and cooperative revitalization. The model structure may be general enough to apply to other fields as well.

51. Fjellså, Olav, "The Development of the Debt-Ratio in a Small Open Economy"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/b2774c70t?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:16Z
Description:
This paper describes a System Dynamics model of the foreign trade sector in a small open economy. The model is used to investigate the consequences of various economic policies aimed at solving problems which a high-cost country may experience when its debt-ratio begins to increase. With the model, we simulate some of the economic consequences of currency devaluation, tax increase, restrictive public policy and income freeze. Each of these measures significantly improve the debt-ratio, but only after a delay of 5-8 years, as a result of various bottlenecks in the decision-making process.

52. Ford, Andrew, "Lessons from Case 1454"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/nv935k82k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:17Z
Description:
The paper is organized in three parts. It begins with a brief review of the substantive exchange of views in the case, including the Company’s position, the Attorney General’s position, and the analyses and counter analyses presented in support of these positions. In Part Two, the paper describes the participants and the schedule of the hearings. It is argued that the rapid pace of these hearings and the background of the participants are important determinants of usefulness of System Dynamics models under adversary proceedings. The third part of the paper concludes with a discussion of the advantages and disadvantages of system dynamics under fast paced, adversary conditions.

53. Forrester,Nathan, "Macroeconomic Stabilization Policy in the Context of Inventory Dynamics"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/mc87q742r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:18Z
Description:
The aggregate demand-aggregate supply (AD-AS) model presented in most intermediate and advanced macroeconomic texts may provide misleading insights into the effects of economic stabilization policies. Conventional analysis of the AD-AS model shows that policies which raise demand during periods of peak unemployment and reduce demand during periods of low unemployment tend to stabilize the economy. This paper: (1) Develops a dynamic model of the AD-AS model; (2) Shows that the model produces a very long period of oscillation (approximately 50 years); (3) Shows that the conventional stabilization policies increase damping of the long cycle; (4) Adds inventories to the base model; (5) Shows that the inventories introduce a business cycle fluctuation to model behavior; (6) Shows that the conventional stabilization policies destabilize the business cycle behavior mode. This paper should help explain why standard “stabilization” policies tend to destabilize the business cycle in the System Dynamics National Model.

54. Franco, Douglas, "The Causal Loop Diagram"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/cc08hz52c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:19Z
Description:
The Causal Loop Diagram, a signed diagraph which shows the variables and interactions of a system Dynamic model, has been studied. It has been found convenient to start with the levels and their interactions. Then signed interactions between levels and rates may proceed. The transformation from signed level diagraph into Causal Loops, in terms of levels and rated, is presented. Dynamics properties such as stability, oscillations, controllability, and observability are related to the information contained in the Causal Loop Diagram. These dynamics properties have been found very useful in the synthesis of policies aimed to manipulate structure. Illustrations and examples are inserted in the exposition.

55. Gaynor, Alan K., "The Dynamics of Stability and Change in Public Schools"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/4m90fc37g?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:21Z
Description:
It was the purpose of this study to describe a modest theory of educational change which could be stated with some precision, which could reproduce observed historical behaviors, which could facilitate an understanding of the structural dynamics giving rise to those behaviors, and which would permit the examination of selected policies which have some historical currency.

56. Golüke, Ulrich, "Behavioral Science and System Dynamics: The Prospect of Symbiosis"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/rx914753v?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:22Z
Description:
To improve matters in the behavioral sciences, system dynamics can play the role of catalyst by providing both the holistic view which is needed to understand the behavior of human beings and not just bits and pieces of their actions and the necessary technical tools to map behavior over into manageable models. In return, system dynamicists will learn how to include a more differentiated and thus more realistic representation of human behavior in their models of social systems.

57. Gottschalk, Petter, "Railroad Decline and Revitalization"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/5425kt716?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:23Z
Description:
The purpose of this paper is to introduce an integrated framework for long-range strategic planning to a railroad. The framework is a computer simulation model designed to be useful to most freight –hauling railroads. The model can help to increase the understanding of problems facing the railroad and to aid in developing strategies for addressing these problems. It is designed to forecast railroad performance and to aid in developing more effective policies for railroad management. It can also be used by Federal agencies to evaluate impacts policy on railroad performance.

58. Graham, Alan K., "Lessons on Modeling from the System Dynamics National Model"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/0c484272m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:24Z
Description:
Since 1972, Jay Forrester and colleagues at MIT have been evolving the System Dynamics National Model (SDNM). The purpose of this model is to guide policy makers in dealing with today’s major problems. The ambitious scope of the project motivates careful examination of modeling practices and how they contribute to the success of the project. The above paper recounts incidents in the development of the SDNM and discusses the related modeling issues.

59. Hobbs, G. D., "A Model of the UK Economy: An Aid to Understanding Economic Behaviour"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/p55488446?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:25Z
Description:
The model in this paper is, therefore, directed towards an understanding of the mechanisms at work during the UK business cycle. Its time horizon is no greater than ten years, with the main emphasis on the next five. It is frequently argued that cycles of longer period than the business cycle exist, e.g. the 50 year long wave. It is not intended that this model should try to capture in detail the mechanisms believed to produce them. However, their role in determining the underlying trend must be recognized, and their effects incorporated exogenously, perhaps by reference “off-line” to other models designed to look at these more distant horizons.

60. Holmes, Robert Kevin, "Examination of Some Aspects of Control within a Framework of Managements and Objectives"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/ms35tt654?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:26Z
Description:
Planning and Control are essential for the success of any human endeavour and are now widely established concepts in most organizations, usually enshrined in formal corporate/planning systems. The process of planning may be analysed in a number of different ways, but generally there is a consensus on the need to split the process up into strategic planning, which directs the organization and tactical or operational planning which deals with the resource allocation for specific operational units and integrates them into the whole.

61. Homer, Jack B., "The Effect of Government Regulation on the emergence of a New Medical Technology"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/0r967n05s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:27Z
Description:
This paper explores the possible paths of emergence of a new medical technology and how those paths might be altered by government regulations of the sort now promulgated by the Food and Drug Administration (FDA). The purpose of the paper is to help clarify the role of FDA regulation in a dynamic context. The analysis focuses on the idea that an emerging technology’s effectiveness may change over time and that the benefits and losses due to regulation may themselves have a dynamic character. An increasingly complex story of the emergence (or dissemination and development) process is told with the help of causal-loop diagrams. Results from a preliminary system dynamics model based on this story are illustrated and discussed. They suggest that the FDA’s actions may have unintended effects, such as slower   development of a technique, which may or may not be harmful. They also suggest that, in certain cases, post-marketing surveillance and communication of results may be at least as important an activity for the FDA as pre-marketing evaluation.

62. Jensen, Jens with Erik Mosekilde, "Dynamic Simulation of Human Ventilatory Regulation"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/hq37w633h?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:28Z
Description:
In order to investigate the regulation of breathing under various conditions, we have developed a dynamic model of the human respiratory and cardio-vascular systems. The model describes the flows of oxygen and carbon dioxide between the atmosphere and the tissues as well as the chemical regulation of breathing in a rather detailed manner. When testing the model with a step increase in muscular metabolism (simulating a transition from rest to physical activity), it reproduces clinical observations for the variation in ventilation and in arterial oxygen and carbon dioxide pressures. The model also reproduces the respiratory response to changes in the composition of the inspired air. Combined with a model of the Hafnia A anaesthetic system, the respiratory system model has finally been used to examine the life-threatening dynamical run-away effects which may occur, if the fresh gas flow is reduced too much, and the patient starts to rebreathe his own expiration.

63. Karsky, Michel, "The Development and Use of System Dynamics within an Industrial Context"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/qj72pr29s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:29Z
Description:
This paper is destined not so much for those who are present at this conference than for the members of the business community whose absence constitutes one of the main problem facing System Dynamics. Indeed, since its inception more than 20 years ago, quite a few Industrial or System Dynamics publications have dealt with industry or government related applications. However, very few of those have been effectively developed within and present by business or government representatives.

64. Kiefer, Charles with Peter M. Senge, "Metanoic Organizations: New Experiments in Social Evolution"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/dj52wp504?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:30Z
Description:
Our work during the past several years leads us to believe that there now exists a small but significant number of American corporations engaged in daring experiments in organizational transformation. These companies fundamentally alter our understanding of how a group of people can work together. They are committed to the absolute highest in organizational performance and human satisfaction. They view themselves as microcosmic demonstrations of how society could work towards everyone’s fulfillment.

65. Keloharju, Raimo Dynamic or ‘Dynamic’ Hypothesis?"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/9593vc512?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:31Z
Description:
The SD approach is based on control theory. As with general system theories, it postulates that system structure causes system behavior. Computer simulation used to be the only means of solving complicated models at the time SD was invented. Therefore: (1) only system structure and system behavior could be used as yardsticks in model validation (2) without an intuitive or intelligent guess, that related structural explanation to model behavior, all modelling work would have been fruitless or at least extremely laborious. In computer simulation, no automatic feedback from model behavior to structural changes is feasible. A human link is needed and, therefore, system dynamists have rightly argued about the significance of insights gained from the very modelling process. Without insights, no feedback mechanism would work properly in model construction. The authoritarian relationship between man and machine, prevailing in SD, is an outgrowth of this situation.

66. Kirchner, James W., "A Methodological Framework for System Dynamics Model Evaluation"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/v979vk77w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:32Z
Description:
The scientific technique known as the method of multiple hypotheses can be adapted to suit the purposes of system dynamics policy modeling.  This method would allow determination of a model’s value through comparison with other competing models. It would also diminish modelers’ emotional attachment to any single theory.  But in adopting this method, system dynamicists would need to develop a new philosophy of model evaluation, emphasizing disproof over verification and comparison among theories over improvement or elaboration on a single model.

67. Krallmann, Hermann, "System Dynamics Models as Decision Support Systems (DSS)"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/wd376d56c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:33Z
Description:
This abstract describes the further development of the project “Introduction `of innovative Products into a competitive Market”, the former stages of which have been already described into the Proceedings of the 1980 International Conference on Cybernetics Society, Cambridge 1980 (Krallmann (1980)). The management of the company we cooperated with wanted to get support in the decision making process of introducing innovative but similar products into a competitive market.

68. Levine, Ralph L., "A Dynamic Model of Recreational Usage"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/6395wr74v?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:34Z
Description:
The motivation for developing this model came from an academic interest in the dynamics of recreational behavior as well as in responding to passing recreational problems faced by state officials and tourist industry planners. The current energy picture and economic climate in Midwestern United States appears to be relatively bleak. Michigan, for example, whose economic life revolves around the state of the automobile industry, is reeling from sharp declines in auto sales. The cost of energy, for the most part, has been increasing over the past eight years at a phenomenal rate, not only increasing the cost of automobiles, but also affecting consumer choices and preferences for smaller and more economical cars.

69. Lyneis, James M., "Increasing the Effectiveness of Corporate Policy Models"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/gt54m562b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:35Z
Description:
The philosophy of constructing models requires that the models be sufficiently detailed in order for them to have a significant impact on the development of detailed corporate plans. Although dynamic behavior may adequately be captured by a “simple” model, our experience in preparing models for a number of corporations indicates that detail is useful to facilitate initial acceptance of the model, and is often essential in assuring the model’s continued use by the client.

70. Maier, Helmut, "Measuring Image and Efficiency in Public Administration: A Dynamic Approach with Empirical Results"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/44558x85w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:36Z
Description:
The background of this paper is an analysis carried out on the occasion of an election within an academic self-administration in West Berlin in 1980/81. This analysis considers (1) papers presented during the time before the election with opposing opinions as to image and efficiency of this administration, and (2) statistical data concerning possibilities within the structure of this administration and the realization of these possibilities by members of the staff over a period of seven years.

71. Mass, Nathaniel J., "Diagnosing Surprise Model Behavior: A Tool for Evolving Behavioral and Policy Insights"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/tx31r1535?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:37Z
Description:
Both in incipient and later phases of developing a model, unexpected behavior is frequently encountered—that is, behavior which is at odds with the initial expectations of the model builder or client. The appearance of such surprise behavior immediately raises two possibilities: either the behavior is implausible, and the model therefore must be revised; or the behavior withstands scrutiny and reveals previously unappreciated aspects of the system. In either instance, the process of diagnosing and interpreting surprise behavior gives a powerful basis for model for model evolution and generating policy insights. But frequently, it is quite difficult in practice to discern whether the incidence of surprise model behavior reveals errors or suggests insights. The paper is designed to contribute to the literature on model formulation, testing, and policy analysis, by discussing the criteria for diagnosing surprise model behavior. Several case examples are presented in which appropriate resolution of surprise model behavior led to significant model improvements and/or behavior insights. Moreover, operational guidelines are presented to increase the likelihood of uncovering and successfully treating surprise behavior.

72. Mode, V. Alan, "Applications of System Dynamics to a Nonprofit Research Organization"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/34850071v?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:38Z
Description:
A particularly interesting area for the application of system dynamics methodology is in business management; especially the interplay of quantitative (financial, economic) and qualitative factors (motivation, morale), and the decision-making choices which confront management. When a firm has a product which can be measured in economic terms, the construction of a model can be quite straight-forward. Even in non-quantitative areas such as research and development, models have provided insight into the decision-making process. While these models have been informative from both a system dynamics and management science perspective, the practical application of the results has been too often lacking. For a businessman, simulations and models are academic exercises unless they provide some measure of practical guidance. It was from a basis of requiring that the system dynamics model provide practical decision-making guidance in real-world environments that we have attempted several studies of R&D projects.

73. Morecroft, John D. W., "System Dynamics: Portraying Bounded Rationality"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/jm215700f?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:39Z
Description:
This paper examines the linkages between system dynamics and the Carnegie school in their treatment of human decision making. It is argued that the structure of system dynamics models implicitly assumes bounded rationality in decision making and that the recognition of this assumption would aid system dynamicists in model construction and in communication to other social science disciplines. The paper begins by examining Simon’s “Principles of Bounded Rationality” which draws attention to the cognitive limitations on the information gathering and processing powers of human decision makers. Forrester’s “Market Growth Model” is used to illustrate the central theme that system dynamics models are portrayals of bounded rationality. Close examination of the model reveals that the information content of decision functions is limited and that the information is processed through simple rules of thumb. In the final part of the paper there is a discussion of the implications of Carnegie philosophy for system dynamics, as it affects communication, model structuring and analysis, and future research.

74. Nguyen, Tanette N., "Comparing Tactical and Strategic Modeling Techniques in the Field of Public School Finance"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/cc08hz53n?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:40Z
Description:
This study proposes to compare two types of computer simulation techniques, namely tactical and strategic simulations. It explores the advantages and disadvantages of the two methods and stresses the importance of the insight to be gained by combining both approaches in the evaluation of public policies. A school finance reform policy is presented as a case study. More specifically, the research evaluates the implementation of a cost-of- education index (a mechanism to adjust for disparities in educational costs among school districts in a state) in the New York State aid formula. The study investigates, using two computer simulation techniques, the impact of this policy in terms of organizing per pupil expenditures.

75. Paich, Mark, "Architectural Cycles in the R"D Process"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/4f16cm05z?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:41Z
Description:
My paper focuses on an extension of the basic R&D model. The basic model uses the concept of an average product which the firm develops and eventually sells. The extended model used in my paper diaggregates products into products and architectures. In the extended model, products are developed and sold just as they are in the basic model. An “architecture” is a basic engineering development which, when completed, enables the firm to develop a large number of products. An investment of resources in architectural development is necessary before marketable products can be created.

76. Perri, Karla, "Designing Models for Policy Purposes: A View from Capitol Hill"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/2z10x733r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:42Z
Description:
Many Congressional and Executive Branch policymakers are becoming discontent with the contribution of models to the policy process. One reason the modeling process and modeling results are being questioned is because of their perceived incomprehensibility and limited utility. This discontent has intensified with the Administration’s proposed reductions in domestic programs. This new mood of austerity is forcing researchers to justify modeling as useful to government policymaking.

77. Polya, Lance, "Structure- Behavior Relations for Certain Nonlinear, Second-Order Systems"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/9k41zx80c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:43Z
Description:
An experiment was conducted using DYNAMO simulation to gain an understanding of the relation between the structure and behavior for a well-defined family of nonlinear, second-order systems. The result of the empirical investigation was 1) a taxonomy of structures—a categorization of the structures that give rise to all of the possible behavior modes; and 2) a set of observations and precepts—simply stated guidelines gleaned from the taxonomy that relate structure and behavior.

78. Probert, David E., "System Dynamics Modelling within the British Telecommunications Business"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/8049gp66k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:44Z
Description:
System Dynamics modeling has been used in the formulation and implementation of strategic planning models for nearly five years within the Long Range and Strategic Studies Division of the British Telecommunications Business. This modelling has proceeded in close collaboration with the Department of Control and Management Systems of Cambridge University. The business itself is a public corporation which means that despite a certain degree of autonomy, it is still ultimately dependent upon the Government for approval of its investment plans and also its investment capital.

79. Pugh, Jack with J. Werb, "Micro-DYNAMO"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/8910kc227?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:45Z
Description:
Mini-DYNAMO has been adapted for the Apple II computer operating under Apple’s PASCAL system. Working within the constraints of a micro-computer, Micro-DYNAMO offers surprising capacity and speed. Models with up to 25 active equations will run in tolerable lengths of time, and models with up to 100 active equations can be run, although the time required to simulate them is rather long.

80. Rahn, R. Joel, "Aggregation in System Dynamics"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/d217r7103?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:46Z
Description:
Stochastic aspects of systems have generally been ignored in most system dynamics studies except for purposes of sensitivity testing. Yet any model that claims to be more than simply an empirical description of a system must treat the underlying stochasticity explicitly in terms of its contribution to the dynamics. Recent work in chemical, biological, and hydrodynamic systems has shown that the aggregation of stochastic effects can lead to novel behavior (self-organization in dissipative systems). In this paper, an analogy between models of these physical and system dynamics models is developed, in which system dynamics models are seen to be an approximation (to lowest order in an expansion in system size) to a stochastic model for the system. The implications of theoretical results derived for the physical system models are evaluated for their application to the system dynamics models. A research strategy to elaborate this to analyzing systems is proposed.

81. Randers, Jørgen, "Waves and Oil Tankers: Dynamics of the Market for Oil Tankers to the Year 2000"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/b8516553n?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:47Z
Description:
The oil tanker market is interesting from a system dynamics point of view. The market exhibits regularities which appear to be caused by an underlying structure which has been stable for at least 30 years, and probably longer. This seemingly stable structure is primarily the result of the systematic, but not particularly rational, behaviour of the main actor in the oil tanker market: the community of shipowners. The collective effect of their individualistic actions, I believe, is a rather violent and rhythmic development in the market- on a timescale of years to decades. The regularity is, of course, superimposed on a non-recurring pattern of developments caused by events entirely outside the control of the oil tanker community. In this paper I describe the stable structure and discuss what it means for the likely development of the oil tanker market over the next decade.

82. Reid, George W., "An Approach for System Dynamics Awareness"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/2j62sn327?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:48Z
Description:
Civil Engineer curricula are made up courses. Curricula also lead to degrees and most engineering curricula provide rather narrow time allocation to fundamental categories of course offering. It is usually a tight curricula, designed to be achieved in four calendar years by the good student, five by the average. It is sequestial in nature.  The upper limit of course hours is usually a constraint,  the addition of new course material must be at the expense of older material. The present curricula are built on science, math, chemistry physics, tools (drafting, surveying, computer programming, statistics), mechanics, dynamics, thermo and materials followed by general engineering and then the various components of civil engineering, such as hydraulics, transportation, sanitary, water resources, structures, materials, etc. This sequence presently produces a B.S. degree holder, ready to emerge on the scene at $18,000 - $30,000/year.

83. Richardson, George P., "Managing R"D in a High-Growth Company: The Significance of Coordinating People and Products"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/rr172f66g?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:49Z
Description:
A number of high technology firms have recently reported increasing delays in the development of computer-related hardware and software. Experiencing increasing product development times and schedule overruns, one such company commissioned a system dynamics study of the management of its product development group. The purpose of this study has been to uncover potential sources for rising product development times in the company and to identify those over which management can exercise some control.

84. Richmond, Barry, "Endogenous Generation of Structural Change in System Dynamics Models: An Illustration from a Corporate Context"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/8s45qt40h?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:50Z
Description:
System Dynamics models have been used extensively for depicting the dynamic behavior which arises from a given underlying feedback structure. In a typical application, a feedback structure is specified, numerical values for model parameters are specified, and then a base-run simulation is conducted. Following the establishment of a Base Case, initial conditions, table functions, constants, policy variables and exogenous inputs are altered; with the resulting impact on model behavior noted and analyzed.

85. Roberts, Nancy, "An Evaluation of Introduction to Computer Simulation: The System Dynamics Approach"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/x633fh992?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:51Z
Description:
With the goal of introducing system dynamics to high school students, a set of six learning packages were written during the 1979-80 academic year under grant number GOD7903439 from the US Office of Education. Co-authors of the material are Nancy Roberts, David Anderson, Ralph Deal, Michael Garet, and William Shaffer. The evaluations from pilot testing done during the grant year in six Greater Boston high schools suggest that the materials indeed can effectively accomplish this introductory role. The teachers involved generally made very positive comments about both the value of system dynamics as an exciting high school project as well as the appropriateness of particular materials.

86. Rohrbaugh, John, "Evaluating Objective Function Trajectories: What is in the Eyes of the Beholder"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/9593vc52b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:52Z
Description:
Although the system dynamics literature covers issues of how to construct, analyze, test, validate, and implement dynamic models, surprisingly little attention has been paid to how managers react to and interpret the output from system dynamics models (see Gardiner and Ford, 1980; Rohrbaugh and Anderson, 1979). That is, system dynamicists construct feedback models that are simplifications of a complex reality and then conduct policy tests on these abridged representations. However, decision makers not trained in system dynamics may find that even these allegedly simplified models may be quite complex and difficult to evaluate, since model output typically consists of scores of variables interwoven over time.

87. Saeed, Khalid, "Rural Poverty and Development Policy in Pakistan: The Case of a Resilient Income Distribution System"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/x633fj00m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:53Z
Description:
This paper attempts to explain the causes of widespread rural poverty which has persisted in Pakistan in spite of the development effort. The paper also analyses the various rural development policies implemented and explains why these policies have had little if any impact on the income of the rural poor. The main instrument of analysis of the study is a system dynamics model incorporating income generation and disbursement processes in an agrarian economy consisting of a capitalist sector and a self-employed sector. The analysis takes into account only the economic factors arising out of the rational decisions of the capitalists and the cultivators. These factors are considered adequate for maintaining rural poverty, although, the role of social and political factors is acknowledged. The study suggests that the absence of an economic force that should encourage ownership of land by its cultivators is a key factor responsible for the poor economic condition of the working rural households. Land is easily separated from cultivators and is concentrated in the capitalist sector. This concentration significantly reduces income in self-employment and thus leaves the cultivators with very little bargaining power for negotiating compensation for labor. Thus, development policies striving to increase productivity may only serve to increase the claim to income on the basis of ownership of resources. If ownership is concentrated outside of the cultivators, such policies may worsen economic condition of the cultivators. The study proposes a general framework for rural development incorporating simultaneously fiscal instruments that should encourage transfer of land ownership to its cultivators and policies that should help increase productivity of land.

88. Spencer, Sue, "The Alcoholic Lifecycles Model"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/4f16cm067?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:54Z
Description:
Alcohol abuse and treatment in the United States cost nearly $43 billion in 1975- including $19.64 billion in lost production, $12.74 billion in health and medical costs, $5.4 billion in motor vehicle accidents, $2.86 billion in violent crimes, $1.94 billion in social responses, and $0.43 billion in fire losses. There are about 13 million problem drinkers (including alcoholics) in the United States. Of these, less than 10 percent seek treatment. For those receiving treatment, the overall improvement rate ranges from 30 to 70 percent, depending on how broadly improvement is defined.

89. Steinberg, Marian N., "Alternative Strategies for managing Long Island’s Hard Clam Resource"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/j6731m795?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:55Z
Description:
Dramatic declines in harvests strengthen the assumption that Long Island’s hard clam fishery may be heading for collapse. A family of predator-prey models has been developed to test and evaluate alternative strategies to reverse the decline in hard clam harvests and/or stabilize the clam population. Harvesting is simulated as a fixed percent of standing stock and the behavior of the baymen in response to price and supply of clams is not included in the models. Five types of policies are evaluated: closed season, maximum size limit, hatchery seeding, bounty on predators, and nursery sanctuaries (closed areas). Effectiveness is judged for both the short term (ten years) and the long term (eleven to twenty years after the policy was instituted). While seeding options produce modest short term improvement in the annual value (8.0 to 10.8 percent), only the two bounty policies produce significant improvement in both the short term (17.0 and 72.6 percent) and the long term (20.4 and 66.4 percent). The results of this model reflect the influence of specific management policies on the biological system alone. A later version, incorporating the behavior of the baymen, will introduce key social and economic factors.

90. Sterman, John D., "Macroeconomic Effects of the Energy Transaction: A Dynamic Policy Analysis"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/9019sk382?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:56Z
Description:
This paper explores the following questions: 1.What are the economic consequences of escalations in unconventional energy costs on terms of economic growth, inflation, real energy prices, energy production, consumption, and imports? 2. To what extent are escalations internally generated by interactions between the energy sector and the rest of the economy?

91. Sterman, John D., "The Growth of Knowledge: Testing a Theory of Scientific Revolutions with a Formal Model"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/bv73ch26b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:57Z
Description:
There has been a dramatic upheaval in our conception of science in recent years. The old notion that science is a logical, rational enterprise continually adding to the stockpile of knowledge has been challenged; many now recognize that the evolution of science is punctuated by violent disruptions. During such crises, or scientific revolutions, a tried and true theory is abandoned for an untested and often heretical alternative. The new theory destroys the old rather than building upon it, and thought he successor may flourish for centuries eventually another crisis develops and another revolution occurs. Some even claim that science is completely anarchic, more a no-holds-barred brawl than a calm, reasoned investigation of reality.

92. Tank-Nielsen, Carsten, "A Play in Four Acts or the Use of System Dynamics as a Catalyst in Public Policy Discussions"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/j098zv708?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:58Z
Description:
As a novice System Dynamicist one learns all the textbook rules and advice of system dynamics modeling. As a practicing System Dynamicist one learns the many shades of rules and advice.  The latter ones are only occasionally spoken about and seldom written down. The experience gained from applying formal modeling technique to a diffuse ambiguous reality, often exist as vague mental models of the various roles a formal simulation model and a policy analyst can play in the public policy formation process.

93. VanderWerf, Pieter, "The Use of Reference Modes in System Dynamics Modeling"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/nz806h10s?file=thumbnail
System Modified Dtsi:
2020-01-02T18:35:59Z
Description:
In the first lecture of the first system dynamics course I ever took the professor presented a list of the steps of a modeling project. During the rest of the semester it became apparent to all of us that actual projects never follow the list very closely. But it also became apparent that the list was useful anyway. It helped organize effort, gave direction to a stalled modeler, and provided a checklist of activities to be addressed (if not always accomplished).

94. Weil, Henry Birdseye, "Effecting Strategy Change with System Dynamics"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/4m90fc391?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:00Z
Description:
A System Dynamics project for a corporate client generally has three objectives: creation of an analytical tool, transfer of a new analysis technology into client organization, and managerial development. In many ways, the first two objectives are means toward the third. Development of new—and shared- perspectives, attitudes, and behaviors among the senior executives can be the most significant benefit from a System Dynamics project. This paper discusses how the process of System Dynamics has been used to draw out diverse points of view, to test and evaluate the differences, to build a consensus regarding key assumptions, to create confidence in the analytical tool which was developed, and, ultimately, to forge a managerial commitment to a new business strategy. The author draws upon several recent applications in the United States and Europe to illustrate the role of System Dynamics in effecting strategy change, and comments on how the process is affected by differences in organizational “culture”.

95. White, C., "Elements of Control in Alliance Force Development"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/w3763r053?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:01Z
Description:
This paper introduces an aggregate view of factors and policies that can influence the development of military forces in two international alliances which see each other as potential adversaries.  The growth of forces observed in the NATO and Warsaw Pact alliances is taken as a reference mode.  A conceptual System Dynamics Model is described which can accommodate a number of different perspectives on this issue.

96. Willett, Lois Schertz, "An Analysis of Energy-Economy Interactions"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/w6634n06m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:02Z
Description:
There is a growing interest in energy and energy policy analysis because of the gap between the United States’ energy consumption and energy production. Numerous policies for dealing with America’s “energy crisis” have been discussed and evaluated. Underlying these policy investigations have been a variety of simulation models designed to analyze energy demand, energy supply, and the interaction between the two. Several of the models used for energy policy analysis do not couple the energy sector to the rest of the economy. Some modeling efforts even assume that there is no causality from energy to GNP. The purpose of this study is to examine the structural relationships that govern the interaction between the energy sector and the rest of the energy policies, so as to contribute to the development of more effective national energy policies. A computer simulation model that illuminates the feedback coupling between the energy sector and the rest of the U.S. economy is used in the analysis. The model is used to analyze the effects of increasing capital intensity of the energy sector on the level of economic output and the efficiency of a general class of conservation initiatives in mitigating those effects. When conservation initiatives are introduced, cumulative energy consumption is reduced and sales and profits of the producing sectors are lower. Average GNP is lower and average general unemployment is higher when conservation is introduced.

97. Wolstenholme, E. F., "Designing and Assessing the Benefits of Control Policies for Conveyor Belt Systems in Underground Coal Mines"

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/sf268q284?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:03Z
Description:
This paper describes the application of System Dynamics in what is traditionally a hard engineering area, but where the application of analytical techniques are limited by the stochastic nature of the system driving forces (coalface output rates) and the need for highly credible, management orientated results. Methods and analysis have thus centered on using discrete simulation techniques based on open system models, primarily to assist in capacity design. The use of System Dynamics in this context is based on two premises. The first of these is that System Dynamics has, in addition to it s softer areas of application, considerable potential to both supplement and enhance Operational Research approaches in the analysis of such systems. Secondly, it is the author’s belief that the key to further development and acceptance of System Dynamics lies in bridging the gap between itself and associated subject fields, such as Operational Research, by direct demonstration of the approach within these fields. Recent technological advances within the coal clearance field have provided an excellent form for such a demonstration.

98. Zahn, Erich, "Systems Dynamics as a Tool for Corporate Planning

Type:
Document
Date Created:
1981
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, 4a97153f59047c298f3bcd6b15c284f5, and e8eac154b3129692f26c222dbc2c9466
Thumbnail Path Ss:
/downloads/1n79hn33c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:05Z
Description:
Corporate modeling in general and System Dynamics modeling in particular have now a history of more than two decades. Despite this fact impacts on the corporate planning process have not been very satisfactory. The reason is that in many cases system dynamics models (as well as other types of corporate models) had not been constructed, validated and implemented adequately for managerial use. They did not provide the information support which is needed in order to make the necessary decision in the various phases of a complex planning process that has a lot to do with major changes in markets, products, production processes, technologies, governmental regulations etc. Here, formal decisions rules as used in operation planning are impractical in most cases.

99. Appiah, R. K. with R.G. Coyle, "A Modern Control Engineering Approach to System Dynamics"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/vd66wh142?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:06Z
Description:
The paper reviews, briefly, the development of system dynamics (SD) and presents a modern control approach. It formulates and solves the SD policy design problem as a model-following control system design problem in an adaptive control framework. A computationally simple policy algorithm based on variable-structure system theory is used as an illustrative example of the stabilization of the dynamic characteristics of a production/raw materials system. Computer simulation results are given for the modern control approach as well as the classical SD techniques. Directions in which the modern control approach could be developed are indicated.

100. Bonnell,William S., "The Evolution of a Model: Computational Aid, Policy Making, Planning and Scheduling "

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/jw827v33c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:36:07Z
Description:
This paper describes the development of a limited resource, backward scheduling, network model for an assembly department using DYNAMO. The model evolved in three stages: a calculation device, a policy exploration tool and a planning and scheduling system. An interesting feature of the model is the representation of the complex flow through various disassembly operations. Graphics and report interfaces with DYNAMO are discussed. The enclosed programs are provided on an as-is basis, without warranty either express or implied. No assurance of successful installation can be given.