Using information criteria to determine the number of regimes in threshold autoregressive models

Threshold autoregressive models can be used to study processes that are characterized by recurrent switches between two or more regimes, where switching is triggered by a manifest threshold variable. In this paper the performance of diverse information criteria for selecting the number of regimes in small to moderate sample sizes (i.e., n=50,100,200) is investigated. In addition it is investigated whether these information criteria can be used to determine whether the residual variances are identical across the regimes. It is concluded that for small sample sizes should be preferred, while for larger sample sizes either BIC or should be considered: The latter is the only information criterion that includes a penalty for the unknown threshold parameters.     

Age of Onset of ADHD in a Sample of Elementary School Students

Examined the age of onset of ADHD symptoms and subtypes using parent ratings of a large sample of elementary school students. Results showed: (1) in children with ADHD-combined type, hyperactive-impulsive symptoms emerged at younger ages than inattention symptoms; (2) about one-fifth of children who met symptom count and impairment criteria for ADHD did not meet the age of onset criterion; (3) Children who did not meet the age of onset criterion consisted primarily of children with inattention problems; and (4) children who did not meet the age of onset criterion had more impaired parent-child relationships, self-esteem, family functioning, and higher overall impairment ratings than children who did meet the criterion. These results raise questions about the validity of the age of onset criterion for ADHD as formulated in DSM-IV.     

A dynamic objective–subjective structure for forest management focusing on environmental issues

In this paper a decision-making process is applied to a Chilean forestry firm that must deal with a host of environmental variables as well as profit making. At the core of this process is a ‘dynamic objective–subjective structure’ founded on the approach that decision making is about comprehending the preferences of the various parties involved and expanding the set of alternatives open to the decision makers. This is in contrast to many models that aim at finding the ‘best alternative’ and to decision analysis approaches that focus on presenting preferences via value functions. The paper describes in chronological order, following the sessions of a decision-making process, how the various components of the structure emerged. In doing so it demonstrates how the process led to an understanding of the real effects of dealing with the environment and how comprehending the preferences led to the introduction of new decision variables. Copyright © 2007 John Wiley & Sons, Ltd.     

Evolution of multi‐criteria analysis: a scientometric analysis

The field of multi‐criteria analysis has known very important developments during the last 20 years, if one considers the very large amount of activities that it has generated and continues to generate (papers in journals, a dedicated journal, books, meetings, applications, …). Even if multi‐criteria analysis has reached some maturity, its future is subject to questions and debate among its researchers: what is the evolution of the field? What is its structure? Is it integrating new topics? In order to answer such questions at least partially, we have studied multi‐criteria analysis literature by means of the method of associated words (scientometric analysis) and the software ‘Leximappe’. All the abstracts of the papers which are relative to multi‐criteria analysis and are included in the bibliographic ABI‐INFORM database from 1985 to 1996 have been analysed. In this paper, we will present some results of this study. Copyright © 1999 John Wiley & Sons, Ltd.     

Multi‐criteria minisum facility location problems

This paper deals with the multi‐criteria Weber (minisum) problem. Several new solution concepts are introduced, related to ideas of equilibrium between the different aspects covered by the objectives. Structural results are presented characterizing the proposed solution sets and showing the relationships existing with the efficient sets in the point objective location problem. Also, algorithms to solve this problem for the polyhedral norm case are developed. The proposed approach is more general than previously studied on multi‐criteria location problems and is particularly applicable in the real world when different scenarios must be compared. Copyright © 1999 John Wiley & Sons, Ltd.     

Reduction of pairwise comparisons in decision making via a duality approach

Although pairwise comparisons have been seen by many as an effective and intuitive way for eliciting qualitative data for multi‐criteria decision making problems, a major drawback is that the number of the required comparisons increases quadratically with the number of the entities to be compared. Thus, often even data for medium size decision problems may be impractical to be elicited via pairwise comparisons. The more the comparisons are, the higher is the likelihood that the decision maker will introduce erroneous data. This paper introduces a dual formulation to a given multi‐criteria decision making problem, which can significantly alleviate the previous problems. Some theoretical results establish that this is possible when the number of alternatives is greater than the number of decision criteria plus one. Copyright © 1999 John Wiley & Sons, Ltd.     

An Experiment on the Numerical Modelling of Verbal Ratio Statements

Verbal statements are intuitively attractive for preference elicitation. In the analytic hierarchy process (AHP) the verbal responses to pairwise comparisons of relative importance are converted into real numbers according to the nine-point integer scale. Several alternative scales have been proposed for the conversion, but sufficient empirical evidence has not been produced to support the choice among these scales. We performed a comparative study in which subjects were requested to quantify verbal ratio statements by adjusting the heights of visually displayed bars. Subjects were also asked to employ verbal expressions in pairwise comparisons of areas of figures with different shapes. The principal result of the experiment was that the perceived meaning of the verbal expressions varies from one subject to the next and also depends on the set of elements involved in the comparison. Our results indicate that there are alternative numerical scales which yield more accurate estimates than the usual 1-to-9 scale and reduce the inconsistency of the comparison matrices. Alternative ways of using verbal preference statements are suggested to overcome the difficulties that arise from the context dependence of verbal pairwise comparisons. © 1997 John Wiley & Sons, Ltd.     

The European school of MCDA: Emergence,basic features and current works

Multiple-criteria decision analysis has evolved considerably since its birth during the 1960s. As part of this evolution, several schools of thought have developed emphasizing different techniques and, more generally, different attitudes as to the way of supporting or aiding decision making. One of these schools is now commonly referred to as the ‘European School’, its members being part of a European Working Group entitled ‘Multicriteria Aid for Decisions’. In the first part of this paper (Section 1) we follow a historical perspective in order to trace the emergence of the European School. Its distinctive features and main ideas are then outlined in Section 2. Finally we provide a general review of the current major research topics developed within this framework (Section 3).     

Combining Patient Utility with Health Status Assessment to Improve Medical Decision Making

Physicians often use health status assessment tools to evaluate a patient's condition, then apply established guidelines to determine the most medically effective treatment. Yet additional criteria, such as the appropriateness of the treatment given the particular patient's preferences and attitude toward risk, are also highly relevant to quality care. While such preferences could be addressed via patient utility functions, their use in actual practice is somewhat limited because elicitation is often considered too burdensome for patients, unreliable, or redundant given other measures. For a small group of real patients who have suffered a stroke, we measure both traditional health status and patient utility for the current state to determine whether limited, focused utility assessment is a practical means of obtaining additional and relevant patient information. We find that utility assessment is perceived as reasonable and useful by patients, even when quite ill, and that utilities and health status are not redundant. In fact, investigating apparent inconsistencies between patient utility and observed health status can alert the physician to patient concerns and criteria not captured by more traditional measures. We propose an approach to medical decision making that uses both measures to improve patient–physician communication.     

Detecting local convexity on the pareto surface

Recent regain in interest in multi‐criteria optimization approaches to provide a designer with multiple solutions to select from and support decisions has led to various methodologies to generate such solutions and possibly approximate the Pareto set. This paper introduces the notions of H‐ and w‐convexities, and develops a simple method to identify local convexity of Pareto hyper‐surfaces since their shape can dictate the choice of the method to use to obtain Pareto solutions and possibly to build an approximation of that set. The method is based on comparing the results from the weighting method to those of the Tchebycheff method at any point on the Pareto hyper‐surface. If, under some conditions, the points obtained from the two methods are identical or not, a local convexity or its lack can be assumed at that location and in its immediate neighbourhood. A numerical example is included. Copyright © 2002 John Wiley & Sons, Ltd.