Bayesian belief networks are being increasingly used as a knowledge representation for reasoning under uncertainty. Some researchers have questioned the practicality of obtaining the numerical probabilities with sufficient precision to create belief networks for large-scale applications. In this work, we investigate how precise the probabilities need to be by measuring how imprecision in the probabilities affects diagnostic performance. We conducted a series of experiments on a set of real-world belief networks for medical diagnosis in liver and bile disease. We examined the effects on diagnostic performance of (1) varying the mappings from qualitative frequency weights into numerical probabilities, (2) adding random noise to the numerical probabilities, (3) simplifying from quaternary domains for diseases and findings—absent, mild, moderate, and severe—to binary domains—absent and present, and (4) using test cases that contain diseases outside the network. We found that even extreme differences in the probability mappings and large amounts of noise lead to only modest reductions in diagnostic performance. We found no significant effect of the simplification from quaternary to binary representation. We also found that outside diseases degraded performance modestly. Overall, these findings indicate that even highly imprecise input probabilities may not impair diagnostic performance significantly, and that simple binary representations may often be adequate. These findings of robustness suggest that belief networks are a practical representation without requiring undue precision.

Dimensional analysis, traditionally used in physics and engineering to identify quantitative relationships, has recently been applied to qualitative reasoning of physical systems. We illustrate some problems of this approach. In the light of this, we reexamine the fundamentals of dimensional analysis in order to more precisely characterize its scope and limitations as a tool in qualitative reasoning. We also explore its relationship to state equation representations of physical systems. In particular, we describe its value in providing a set of constraints to reduce the ambiguity that bedevils qualitative reasoning schemes. We argue that dimensional analysis should not be seen as a substitute for knowledge about the physics but rather a supplement to other sources of knowledge.

'Explaining away' is a common pattern of reasoning in which the confirmation of one cause of an observed or believed event reduces the need to invoke alternative causes. The opposite of explaining away also an occur, where the confirmation of one cause increases belief in another. A general qualitative probabilistic analysis of intercausal reasoning is provided and the property of the interaction among the causes (product synergy) that determines which form of reasoning is appropriate is identified. Product synergy extends the qualitative probabilistic network (QPN) formalism to support qualitative intercausal inference about the directions of change in probabilistic belief. The intercausal relation also justifies Occam's razor, facilitating pruning in the search for likely diagnoses.>

Despite their different perspectives, artificial intelligence (AI) and the disciplines of decision science have common roots and strive for similar goals. This paper surveys the potential for addressing problems in representation, inference, knowledge engineering, and explanation within the decision-theoretic framework. Recent analyses of the restrictions of several traditional AI reasoning techniques, coupled with the development of more tractable and expressive decision-theoretic representation and inference strategies, have stimulated renewed interest in decision theory and decision analysis. We describe early experience with simple probabilistic schemes for automated reasoning, review the dominant expert-system paradigm, and survey some recent research at the crossroads of AI and decision science. In particular, we present the belief network and influence diagram representations. Finally, we discuss issues that have not been studied in detail within the expert-systems setting, yet are crucial for developing theoretical methods and computational architectures for automated reasoners.

Some key issues in evaluating advanced information systems are illustrated by the evaluation of a system, named Demos, for decision modeling and uncertainty analysis. Evaluating an information system is particularly hard when it is intended not just to help users do something faster or more reliably, but also to transform the way they do it. Demos is a nonprocedural modeling system designed to encourage policy analysts to deal more effectively with uncertainty. It is intended to facilitate and encourage more systematic sensitivity analysis, a probabilistic treatment of uncertainty, exploration of alternative model formulations, and clearer communication of model assumptions and implications. A wide variety of approaches to experimentation and evaluation of the use of the Demos system for decision modeling suggest that such an environment can indeed facilitate more effective modeling, at least by expert analysts, but its power also opens up new pitfalls for novices. Implications for further developments of such systems and the need for better tutorial material are explored. © 1986 John Wiley & Sons, Inc.

article Glide: a language for design information systems Share on Authors: Charles Eastman Carnegie-Mellon University Carnegie-Mellon UniversityView Profile , Max Henrion Carnegie-Mellon University Carnegie-Mellon UniversityView Profile Authors Info & Claims ACM SIGGRAPH Computer GraphicsVolume 11Issue 2Summer 1977 pp 24–33https://doi.org/10.1145/965141.563863Online:20 July 1977Publication History 37citation489DownloadsMetricsTotal Citations37Total Downloads489Last 12 Months21Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access