Prof. em. Dr.
+41 71 224 2382
Now showing 1 - 10 of 23
PublicationContributions to Model Validation: Hierarchy, Process, and CessationIn the domain of dynamic modeling and simulation, the assurance of model validity is a prominent challenge. An extensive number of contributions concerning model tests, terminology, and the epistemological foundations of validation have been elaborated. These contributions, however, do not fully answer the questions for novice modelers, namely, which validation tests to choose, when and how to apply them, and at what point to cease their formal validation efforts. Our intention here is to help close this gap by introducing a complexity hierarchy of validation tests, an integrative validation process, and a decision heuristic about when to stop formal validation efforts. The paper concludes by providing directions for future research.Type: journal articleJournal: System Dynamics ReviewVolume: 28Issue: 2DOI: 10.1002/sdr.1466
Scopus© Citations 61
PublicationOperational Closure and Self-Reference : On the Logic of Organizational ChangeThe concept of autopoiesis introduced by Maturana and Varela has, in the last four decades, triggered intellectual efforts for the understanding of phenomena of self-organization in general. This contribution aims at conceptualizing and applying two aspects of autopoiesis-operational closure and self-reference-in respect of social organizations. We formalize these concepts and demonstrate their power to explain change processes. This is achieved by means of a qualitative case study and a quantitative simulation model, which lead to counterintuitive insights about the dynamics of organizational transformation.Type: journal articleJournal: Systems Research and Behavioral ScienceVolume: 29Issue: 4DOI: 10.1002/sres.2111
Scopus© Citations 9
PublicationSystem Dynamics as Model-Based Theory BuildingThis paper introduces model-based theory building as a feature of system dynamics (SD) with large potential. It presents a systemic approach to actualizing that potential, thereby opening up a new perspective on theory building in the social sciences. The question addressed is if and how SD enables the construction of high-quality theories. This contribution is based on field experiment type projects which have been focused on model-based theory building, specifically the construction of a middle-range theory - not a general one. The process of model building and validation is analysed from a theory-building perspective. The resulting theory is evaluated by means of a set of criteria for high-quality theories. As a conclusion, the insighths thus gained are presented and condensed in a tentative set of heuristic principles for model-based theory building.Type: journal articleJournal: Systems Research and Behavioral ScienceVolume: 25Issue: 4
PublicationCrisis Prevention : What Is Necessary to Avoid the Next Crisis?The current economic crisis could deliver valuable lessons for economic agents. However, it seems that those have not learnt essential lessons, continuing their "business as usual". A dynamic simulation model presented in this chapter highlights that this is likely to lead to the next crunch in the offing. Even before we have mastered this crisis the next one is already looming. Does prevention have a chance? How can it be achieved?Type: conference paper
PublicationA Validation Methodology for System Dynamics ModelsThis paper joins into the effort of the System Dynamics community for higher model quality. The literature in the field has bred a number of contributions concerning tests for the validation of System Dynamics models and the epistemological foundations of validation. To date, however, little has been said about a validation methodology for simulations, especially for System Dynamics models. By validation methodology, we understand the systematic elicitation, description, and reflection of issues related to the subject ‘validation'. The paper's over-all contribution is a blueprint for a validation methodology. We explicitly address the follow-ing three topics: Complexity engineering through validation tests, integrated validation proc-ess, and finally the ‘cessation decision'. The first defines validation tests according to their capability to absorb model complexity; the second designs a validation process which ad-dresses the domains of validation (structure, behaviour and context validation) and the degree of resolution (micro, meso, macro) integratively and iteratively. And third, ‘cession decision' creates a heuristic method for the saturation of a System Dynamics model and conceptually defines when to cease with validation efforts. The paper concludes by pointing out further directions of research about a validation methodology.
PublicationNew Frontiers in the Validation of Simulation Models - Structural Dominance AnalysisModels should be relevant for coping with the complexity of the real world. At the same time, the methods by which they are constructed and validated must be rigorous; otherwise the quality of the model suffers. We take a test of model structure, demonstrating a new technique of analysis of the model's structure called Structural Dominance Analysis (SDA). SDA has been developed in the science of complex systems [Kampmann and Oliva 2006; Kampmann and Oliva 2009]. SDA makes use of one axiom of System Dynamics: model structure influences the behavioral outcome of a simulation [Forrester 1993]. In principle, SDA evaluates the relative partial influence of individual feedback loops on the behavior of the variables of interest. Based on this evaluation, loop dominance then signifies which particular piece of model structure is dominant, i.e., most influential for the behavior in a certain period of time. Research about loop dominance has bred several formal and informal techniques to enable SDA [Kampmann and Oliva 2008]. In this paper, we revert to an behavioral technique by Ford . The rationale for using SDA as a validation method is to compare the discovered dominant model structures with the model structures the modeler or expert perceives as dominant in the real system under study. Especially, the comparison of the shifts of dominance between structures over time is a fruitful source for model validation. In this respect, the presented approach is based on a formal quantitative analysis, but for the interpretation it relies on a qualitative comparison of the model with the real system under study. The Structural Dominance Test (SDT) is a means of validating the macro-structure of a simulation model. To apply SDA for the issue of validation is a novelty of this paper. Its application requires a feedback based, continuous-time simulation model, as used in System Dynamics. A brief case study demonstrates the new technique for validation purposes.Type: conference paperJournal: Lecture Notes in Computer Science (LNCS)Volume: Volume 5717
Scopus© Citations 3
PublicationModeling as Theory-BuildingThe purpose of this contribution is to make the idea of modeling as theory-building operational. We conceive the modeling process as a theory-building process, thereby opening up a new perspective on the methodology of modeling in the social sciences. By reconceptualizing the notion of modeling, we hope to convey the advantages of more conceptual thinking in management. Practitioners could gain effectiveness in dealing with external complexity if they would espouse the modeling task as a disciplined reflection and communication geared toward the elaboration of theories. This contribution is based on projects in which System Dynamics models for real-world issues were constructed together with corporate partners. To clarify the isomorphic nature of theory-building and formal modeling and illustrate the approach to modeling as theory-building, one of these modeling ventures is described in detail
PublicationModeling as Theory-BuildingThe purpose of this contribution is to make the idea of modeling as theory-building operational. We conceive the modeling process as a theory-building process, thereby opening up a new perspective on the methodology of modeling in the social sciences. By reconceptualizing the notion of modeling, we hope to convey the advantages of more conceptual thinking in management. Practitioners could gain effectiveness in dealing with external complexity if they would espouse the modeling task as a disciplined reflection and communication geared toward the elaboration of theories. This contribution is based on projects in which System Dynamics models for real-world issues were constructed together with corporate partners. To clarify the isomorphic nature of theory-building and formal modeling and illustrate the approach to modeling as theory-building, one of these modeling ventures is described in detail.Type: conference paper
PublicationModellbasiertes Management : Konferenz für Wirtschafts- und Sozialkybernetik KyWi 2013 vom 4. bis 5. Juli 2013 in BernType: bookVolume: 1. Auflage Januar 2014Issue: 29
PublicationSystem Dynamics Modeling: Validation for Quality AssuranceType: book section