Exploring Structure -Behavior Relations in Nonlinear Dynamic Feedback Models
Guneralp, Burak
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Permalink
https://hdl.handle.net/2142/83116
Description
Title
Exploring Structure -Behavior Relations in Nonlinear Dynamic Feedback Models
Author(s)
Guneralp, Burak
Issue Date
2006
Doctoral Committee Chair(s)
George Gertner
Department of Study
Natural Resrouces and Environmental Sciences
Discipline
Natural Resrouces and Environmental Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Environmental Sciences
Language
eng
Abstract
Formal dynamic model analysis tools are essential in understanding how model structure drives behavior. A model analysis approach is formulated based on eigenvalue elasticity analysis in this dissertation. Eigenvalue elasticity analysis, although a potentially strong formal model analysis tool, has drawn criticisms over the years for a number of reasons. The approach proposed in this study attempts to bring proper solutions to the issues raised by those criticisms. First, a ten-step procedure is proposed to increase the accessibility of the EEA to a wider audience. Among the most prominent features of the proposed procedure is a new measure that takes all modes of the model into account and a normalization approach for calculated elasticity values. Others include the ability to track the loop dominance dynamics over time, and an attempt at codifying the proposed features of the EEA and the ability to track the influences of feedback loops on a specific variable of interest. Several programming codes written for these proposed features are also presented. The proposed approach is applied on a number of dynamic feedback models, taken from the literature. These case studies not only demonstrate the application of the proposed methodology but also bring an improved theoretical/practical understanding to the issues these models address. The analysis on a tree mortality model proved useful in understanding how the simulated tree responds to various stresses according to two apparently different hypotheses. The methodology is also implemented on a budworm outbreak model, which provided some insight on potential policy options for prevention and management of a budworm outbreak but also revealed some of the areas where the EEA needs further improvement. An off-shoot of this study is an improved procedure to loop selection in demographic population studies. The proposed procedure increases the power of demographic loop analysis by identifying only those loops that are forward flowing with positive elasticity values. Finally, the contributions of the proposed improvements to formal model analysis, the areas where there is a need for further improvement and testing of the EEA, and the major findings from the case studies are discussed.
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