This volume is an outgrowth of a NATO Advanced Research Workshop on "Expert Judgment and Expert Systems," held in Porto, Portugal, August 1986. Support for the Workshop was provided by the NATO Division of Scientific Affairs, the U.S. Army Research Institute, and the U.S. National Science Foundation. The Workshop brought together researchers from the fields of psychology, decision analysis, and artificial intelligence. The purposes were to assess similarities, differences, and complementarities among the three approaches to the study of expert judgment; to evaluate their relative strengths and weaknesses; and to propose profitable linkages between them. Each of the papers in the present volume is directed toward one or more of those goals. We wish to express our appreciation and thanks to the following persons for their support and assistance: John Adams, Vincent T. Covello, Luis da Cunha, Claire Jeseo, B. Michael Kantrowitz, Margaret Lally, Judith Orasanu, R. M. Rodrigues, and Sandor P. Schuman.

The subject of this volume--uncertainties in risk assessment and management--reflects an important theme in health, safety, and environ mental decision making. MOst technological hazards are characterized by substantial uncertainty. Recent examples include nuclear waste disposal, acid rain, asbestos in schools, carcinogens in food, and hazardous waste. realing with such uncertainty is arguably the most difficult and challeng ing task facing risk assessors and managers today. Four primary sources of uncertainty in risk assessment and management can be identified: (1) uncertainties about definitions; (2) uncertainties about scientific facts; (3) uncertainties about risk perceptions and atti tudes; and (4) uncertainties about values. Uncertainties about definitions derive primarily from disagreements about the meaning and interpretation of key concepts, such as probability. Uncertainties about scientific facts derive primarily from disagreements about failure modes, the probability and magnitude of adverse health or environmental consequences, cause and effect relationships, dose-response relationships, and exposure patterns. Uncertainties about risk perceptions and attitudes derive primarily from disagreements about what constitutes a significant or acceptable level of risk. Uncertainties about values derive primarily from disagreements about the desirability or worth of alternative risk management actions or conse quences. The papers in this volume address each of these sources of uncertainty from a variety of perspectives. Reflecting the broad scope of risk assess ment and risk management research, the papers include contributions from safety engineers, epidemiologists, toxicologists, chemists, biostatisticians, biologists, decision analysts, economists, psychologists, political scien tists, sociologists, ethicists, and lawyers.

This volume is the outcome of a recent NATO Advanced Study Institute (ASI) on "Technology Assessment. Environmental Impact Assessment. and Risk Analysis: Contributions from the Psychological and Decision Sciences." The Institute was held in Les Arcs. France and functioned as a high level teaching activity during which scientific research results were presented in detail by eminent lecturers. Support for the Institute was provided by grants from the NATO Division of Scientific Affairs. the u.S. Office of Naval Research. and the Russell Sage Foundation. The Institute covered several areas of research. including quantitative studies on decision and judgmental processes. studies on human intellectual limitations. studies on risk attitudes and perceptions. studies on factors contributing to conflicts and disputes about hazardous technologies and activities. studies on factors influencing forecasts and judgments by experts. studies on public preferences for decisionmaking processes. studies on public responses to technological hazards. and case studies applying principles and methods from the psychological and decision sciences in specific settings.