Computer-assisted Reasoning

Published in: Computing in science and engineering, v. 3, no. 2, Mar./Apr. 2001, p. 71-76

Posted on on January 01, 2001

by Steven C. Bankes, Robert J. Lempert, Steven W. Popper

Read More

Access further information on this document at

This article was published outside of RAND. The full text of the article can be found at the link above.

Computer models provide a powerful tool for reasoning about difficult problems. Most computer modeling to date has used a familiar strategy for creating models. Those details that matter most are represented as accurately as possible, and all details not central to the problem are simplified or omitted. This traditional use of computer models has helped with many problems, but those that combine significant complexity with deep uncertainty can make this classical strategy difficult to employ. In these circumstances, knowing which details matter is difficult-models are prone to be incomplete, leaving out details that could matter under some conditions. Parametric or even structural uncertainties remain implicit so that no matter how detailed a model we create, we cannot confidently rely on its predictions about the real system's behavior. For these hard problems, any model we construct is a flawed mirror, potentially deceiving as well as illuminating.

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.