Models, Uncertainty, and the Sandia V&V Challenge Problem

ASME 2018 Verification and Validation Symposium ◽

10.1115/vvs2018-9308 ◽

2018 ◽

Author(s):

George A. Hazelrigg ◽

Georgia-Ann Klutke

Keyword(s):

Decision Theory ◽

Current Literature ◽

Ill Posed ◽

Solution Techniques

In this paper, we argue that the Sandia V&V Challenge Problem is ill-posed in that the answers sought do not, mathematically, exist. This effectively discredits both the methodologies applied to the problem and the results, regardless of the approach taken. We apply our arguments to show the types of mistakes present in the papers presented in J. of VVUQ along with the Challenge Problem. Further, we show that, when the problem is properly posed, both the applicable methodology and the solution techniques are easily drawn from the well-developed mathematics of probability and decision theory. The unfortunate aspect of the Challenge Problem as currently stated is that it leads to incorrect and inappropriate mathematical approaches that should be avoided and corrected in the current literature.

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Models, Uncertainty, and the Sandia V&V Challenge Problem

Journal of Verification Validation and Uncertainty Quantification ◽

10.1115/1.4046471 ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

George A. Hazelrigg ◽

Georgia-Ann Klutke

Keyword(s):

Probability Theory ◽

Decision Theory ◽

Uncertainty Quantification ◽

Model Validation ◽

Current Literature ◽

Current Approach ◽

Ill Posed ◽

Solution Techniques

Abstract The purpose of this paper is not to present new results; rather, it is to show that the current approach to model validation is not consistent with the accepted mathematics of probability theory. Specifically, we argue that the Sandia V&V Challenge Problem is ill-posed in that the answers sought do not, mathematically, exist. We apply our arguments to show the types of mistakes present in the papers presented in the Journal of Verification, Validation and Uncertainty Quantification, Volume 1,1 along with the challenge problem. Further, we argue that, when the problem is properly posed, both the applicable methodology and the solution techniques are easily drawn from the well-developed mathematics of probability and decision theory. The unfortunate aspect of the challenge problem as currently stated is that it leads to incorrect and inappropriate mathematical approaches that should be avoided and corrected in the current literature.

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The ambiguity dilemma in procurement projects

Journal of Business and Industrial Marketing ◽

10.1108/jbim-05-2018-0157 ◽

2019 ◽

Vol 34 (4) ◽

pp. 792-800 ◽

Cited By ~ 4

Author(s):

Mehdi Rajabi Asadabadi ◽

Keiran Sharpe

Keyword(s):

Game Theory ◽

Decision Theory ◽

Current Literature ◽

Design Methodology ◽

Imperfect Information ◽

Rational Agency ◽

Content Type ◽

Procurement Process

PurposeThe purpose of this paper is to use game theory and ambiguity theory to show how “economically rational” vendors will behave in a procurement process that runs over more than one period. In light of that behavior, we have proposed “economically rational” counter-strategies on the part of purchasers.Design/methodology/approachBased on a perception–expectation framework, a unique game-based approach is designed. The authors have proposed “economically rational” counter-strategies on the part of purchasers, which are premised on the theory of rational agency.FindingsAmbiguity in the procurement process is a bane for procuring principals and a boon for suppliers – for the former, it is an issue to be managed, and for the latter it provides an opportunity to extract “insurance rents” from the principals. The authors show that, under certain conditions, the contracting principal can be exploited by a rational, rent-extracting vendor. In particular, they show that there is an incentive for a vendor to delay the resolution of ambiguities in the contract until late in the procurement process, when the insurance rents are at a maximum.Originality/valueThis study contributes to the current literature by highlighting an existing problem in the procurement process and describing it using decision theory under ambiguity in a game-like setting. Specifically, the authors use game theory in a unique way to deal with imperfect information coupled with ambiguity.

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Representation, abstraction, and simple-minded sophisticates

Behavioral and Brain Sciences ◽

10.1017/s0140525x19002942 ◽

2020 ◽

Vol 43 ◽

Author(s):

Peter Dayan

Keyword(s):

Decision Theory ◽

Predictive Coding ◽

Bayesian Decision Theory ◽

Bayesian Decision ◽

Model Based ◽

Model Free

Abstract Bayesian decision theory provides a simple formal elucidation of some of the ways that representation and representational abstraction are involved with, and exploit, both prediction and its rather distant cousin, predictive coding. Both model-free and model-based methods are involved.

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Information and estimation in image processing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125142 ◽

1987 ◽

Vol 45 ◽

pp. 14-17

Author(s):

B. Roy Frieden

Keyword(s):

Image Processing ◽

Optical System ◽

Large Amplitude ◽

Communication Theory ◽

Image Data ◽

Direct Approach ◽

Ill Posed

Despite the skill and determination of electro-optical system designers, the images acquired using their best designs often suffer from blur and noise. The aim of an “image enhancer” such as myself is to improve these poor images, usually by digital means, such that they better resemble the true, “optical object,” input to the system. This problem is notoriously “ill-posed,” i.e. any direct approach at inversion of the image data suffers strongly from the presence of even a small amount of noise in the data. In fact, the fluctuations engendered in neighboring output values tend to be strongly negative-correlated, so that the output spatially oscillates up and down, with large amplitude, about the true object. What can be done about this situation? As we shall see, various concepts taken from statistical communication theory have proven to be of real use in attacking this problem. We offer below a brief summary of these concepts.

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Word Prompt Programs

American Journal of Speech-Language Pathology ◽

10.1044/1058-0360.0603.57 ◽

1997 ◽

Vol 6 (3) ◽

pp. 57-65 ◽

Cited By ~ 5

Author(s):

Lisa A. Wood ◽

Joan L. Rankin ◽

David R. Beukelman

Keyword(s):

Learning Disabilities ◽

Current Literature ◽

Word Processing ◽

Computer Software ◽

Written Language ◽

Written Communication ◽

Speech Language Pathologists ◽

Basic Word ◽

The Matrix ◽

Language Needs

Word prompt programs are computer software programs or program features that are used in addition to basic word processing. These programs provide word lists from which a user selects a desired word and inserts it into a line of text. This software is used to support individuals with severe speech, physical, and learning disabilities. This tutorial describes the features of a variety of word prompt programs and reviews the current literature on the use of these programs by people with oral and written language needs. In addition, a matrix that identifies the features contained in eight sample word prompt programs is provided. The descriptions of features and the matrix are designed to assist speech-language pathologists and teachers in evaluating and selecting word prompt programs to support their clients' oral and written communication.

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