MULTICRITERIA OPTIMIZATION: A GENERAL CHARACTERIZATION OF EFFICIENT SOLUTIONS*

In the context of deterministic multicriteria maximization, a Pareto optimal, nondominated, or efficient solution is a feasible solution for which an increase in value of any one criterion can only be achieved at the expense of a decrease in value of at least one other criterion. Without restrictions of convexity or continuity, it is shown that a solution is efficient if and only if it solves an optimization problem that bounds the various criteria values from below and maximizes a strictly increasing function of these several criteria values. Also included are discussions of previous work concerned with generating or characterizing the set of efficient solutions, and of the interactive approach for resolving multicriteria optimization problems. The final section argues that the paper's main result should not actually be used to generate the set of efficient solutions, relates this result to Simon's theory of satisficing, and then indicates why and how it can be used as the basis for interactive procedures with desirable characteristics.     

THE USE OF ARCS AND NODES FOR THE DETERMINATION OF CRITICAL PATHS IN PERT/CPM NETWORKS

The critical path in a PERT/CPM network is determined in various textbooks by finding the path with associated minimal slack for the network arcs or by finding the path with associated minimal slack for the network nodes. This paper points out that the use of nodes can result in a network path being incorrectly identified as a path of maximum length.     

ON PREDICTING COMPUTATIONAL TIME OF A BRANCH AND BOUND ALGORITHM FOR THE ASSIGNMENT OF FACILITIES

Experience with branch and bound algorithms indicates that computational time is a function of not only the size of the problem, but also the nature of the input data. This paper formulates statistically-based variables which describe certain characteristics of the input data and experimentally evaluates their ability to predict computational time for one branch and bound algorithm, the relative location of facilities or “plant layout” problem. Results suggest that the described experimental procedure may be useful for an a priori assessment of the computational difficulty of specific branch and bound problems.     

The Politics of Hope and Despair: The Effect of Presidential Election Outcomes on Suicide Rates*

Objectives. This article examines the effect of election outcomes on suicide rates by combining the theory of social integration developed by Durkheim with the models of rational choice used in economics. Methods. Theory predicts that states with a greater percentage of residents who supported the losing candidate would tend to exhibit a relative increase in suicide rates. However, being around others who also supported the losing candidate may indicate a greater degree of social integration at the local level, thereby lowering relative suicide rates. We therefore use fixed‐effects regression of state suicide rates from 1981 to 2005 on state election outcomes during presidential elections to determine which effect is stronger. Results. We find that the local effect of social integration is dominant. The suicide rate when a state supports the losing candidate will tend to be lower than if the state had supported the winning candidate—4.6 percent lower for males and 5.3 percent lower for females. Conclusion. Social integration works at many levels; it not only affects suicide risk directly, but can mediate other shocks that influence suicide risk.     

The impact of ethnicity on attitudes toward health care reform in New Mexico

Latinos tend to have significantly lower levels of access to general and top quality medical care than do non-Latino whites, and although disparities in access to health care have diminished for all other minority groups over time, they have widened for Latinos. Given these trends, current attempts to provide universal health care at both the national and state levels across the United States have large implications for the health status of Latinos. The objective of this analysis is to determine whether Latinos have different attitudes regarding health reform than non-Latino whites. Our data are from a statewide random digit dialing telephone survey of New Mexico residents, age 18 and older, conducted in the Fall of 2007. With a Latino population of 44% and ongoing health care reform efforts by the state legislature, New Mexico is an ideal location for this analysis. After controlling for a host of individual level factors, our findings suggest that while Latinos are less likely to identify health care as a salient state issue relative to the economy and crime, they are more likely than non-Latino whites to believe affordable health care programs are important. Finally, Latinos view employers, more than government or individuals, to be responsible for expanding health care coverage.     

Interplay between Friends' Aggression and Friendship Quality in the Development of Child Aggression during the Early School Years

The aim of this study was to investigate the unique and combined role of friendship quality and friends' aggression in regard to the persistence of young children's physical aggression from kindergarten to grade 2. The sample included 1555 children (808 girls) assessed annually using teacher ratings. Two theoretical perspectives (i.e., the social learning and the social bonding perspectives) served as frameworks to guide the analyses and interpret the results. In line with the social learning perspective, friends' aggression was related to a significant increase in children's physical aggression. However, in line with the social bonding perspective, good friendship quality played both a compensatory and a protective role, by, respectively, reducing children's initial level of physical aggression and by mitigating, albeit marginally, the associations between friends' and children's physical aggression. These results suggest that fostering a positive relationship between friends in the early school years may decrease physical aggression even if the friends are aggressive.     

Non-parametric estimation of population size from capture–recapture data when the capture probability depends on a covariate

Summary.  In capture–recapture experiments the capture probabilities may depend on individual covariates such as an individual's weight or age. Typically this dependence is modelled through simple parametric functions of the covariates. Here we first demonstrate that misspecification of the model can produce biased estimates and subsequently develop a non-parametric procedure to estimate the functional relationship between the probability of capture and a single covariate. This estimator is then incorporated in a Horvitz–Thompson estimator to estimate the size of the population. The resulting estimators are evaluated in a simulation study and applied to a data set on captures of the Mountain Pygmy Possum.     

Stochastic Modelling of Times to Temperature for Furnaces Supplying Titanium Blooms to a Rolling Mill at TIMET

In conjunction with TIMET at Waunarlwydd (Swansea, UK) a model has been developed that will optimise the scheduling of various blooms to their eight furnaces so as to minimise the time taken to roll these blooms into the finished mill products. This production scheduling model requires reliable data on times taken for the various furnaces that heat the slabs and blooms to reach the temperatures required for rolling. These times to temperature are stochastic in nature and this paper identifies the distributional form for these times using the generalised F distribution as a modelling framework. The times to temperature were found to be similarly distributed over all furnaces. The identified distributional forms were incorporated into the scheduling model to optimise a particular campaign that was run at TIMET Swansea. Amongst other conclusion it was found that, compared to the actual campaign, the model produced a schedule that reduced the makespan by some 35%.     

Institutions,inculcation, and black racial identity: pigmentocracy vs. the rule of hypodescent

This research paper investigates the effect political institutions have on black racial identity. In particular, I study individual inculcation in contexts where political institutions institutionalize either of two forms of racial social structures – a pigmentocracy (the Dominican Republic), or the rule of hypodescent (the US South), and the effect such inculcation has on black racial identity. I sampled 101 respondents from the Dominican Republic and 102 from the state of Mississippi, USA. Consistent with the basic assumptions of my hypotheses, respondents in the Dominican Republic study sites showed a weaker degree of identification with blackness vis-à-vis something ‘whiter’. Nevertheless, respondents in the Dominican Republic sites demonstrated a stronger identification with blackness than what most conventional observers would have anticipated. Respondents in the Mississippi study sites showed a stronger sense of identification with blackness. Surprisingly, however, Mississippi respondents demonstrated a larger degree of neutrality than expected in their belief of being of a mixed racial heritage rather than just a black African heritage.