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Thematic Guide to Integrated Assessment Modeling
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Integrated Assessment Support Systems
Several developers of computer software are working on systems to facilitate the development and management of models and their ease of use by non-experts. These developments may substantially change the work of assessment and modeling. These tools promise to increase the ease, flexibility, and transparency with which component activities of assessment, such as building and revising models, describing and propagating uncertainty, and analyzing sensitivity, can be done. Increasing the accessibility, ease, and communicability of these tasks can change the fundamental organization of assessment activities by making them accessible to a wider community with less specialized technical training and making them easier and faster to do and to discuss. The borders of this set are not well-defined; in some respects, even powerful spreadsheet programs should be included. Consequently, this section describes a small set, largely chosen by accident of familiarity.Globesight from Systems Applications Inc., is a system for model management and scenario development that can bring together a variety of models describing the system to be studied, together with other forms of information, all accessible through a common user interface. Globesight is structured in the form of four "bases": an "Information base" that contains historical data time-series and text; a "Models base" that coordinates and manages runs of multiple models, including models at different resolutions or levels of aggregation; a "Tools base" that permits various forms of meta-model analysis, including sensitivity, uncertainty, and decision analysis; and an "Issues base" that holds scenarios and results from previously conducted analyses. Globesight has been applied to global climate change by creating a models base that includes the Edmonds-Reilly energy model and DICE Model, and to which will soon be added IMAGE, GREEN, and Global 2100 (Mesarovic 1994).
The driving principle of the Globesight project is to provide a system in which a senior policy-maker can interact intensively with suites of models and other related data. The goal is to integrate human decision-makers into a modeling system, both to allow the decision-makers to test hypotheses, develop scenarios, and learn about the implications of various causal structures of the modeled system and to allow the decision-maker's expert judgment to provide an iterative control on model assumptions or scenarios that generate implausible results.
Other modeling tools include DEMOS, from Lumina Decision Systems, a modeling system for the Macintosh that permits graphical construction of modular models through influence diagrams, flexible specification of probability distributions, and full propagation of uncertainty through models. This system is used for the ICAM models developed at Carnegie Mellon University. A version for UNIX systems has been under development for some time (Morgan and Henrion 1990). Stella and IThink, from High-Performance Systems, are a pair of modeling tools to support systems dynamics models. IMAGE was originally developed in Stella. WhatIf?, from Robbert Associates, is a transparent modeling system implemented on a UNIX server with Macintosh clients, allowing graphical construction of influence-diagram models and extremely powerful graphical presentation of results (ROBBERT Associates 1992). This system presently does not include any meta-model processing, such as scenario or sensitivity analysis or sampling and propagation of uncertainty. A system under development at RIVM, called M, will combine a dynamic mathematical modeling language with a graphical user interface (de Bruin et al. 1994). The M system is being used for development of the TARGETS model.
The next section is Facilitating Entities.
