Automatic starting point selection for function optimization

Traditional (non-stochastic) iterative methods for optimizing functions with multiple optima require a good procedure for selecting starting points. This paper illustrates how the selection of starting points can be made automatically by using a method based upon simulated annealing. We present a hybrid algorithm, possessing the accuracy of traditional routines, whilst incorporating the reliability of annealing methods, and illustrate its performance for a particularly complex practical problem.Now at the Statistical Laboratory, University of Cambridge, 16 Mill Lane, Cambridge, CB2 1SB, UK.     

Voting rules and election outcomes: When does the true majority win?

Majority-in-unit (MIU) and method of majority decision (MMD) voting rules are investigated to determine their impact on the outcome of union elections. A theoretical foundation is established to explain why voters may rationally choose not to vote in these settings. Numerical simulations are employed to compute the probability that the population majority wins the election. The results for these two methods are compared to see which one is most likely to award the election to the true population majority.     

Risk Assessment for Aflatoxin: An Evaluation Based on the Multistage Model

Lifetime cancer potency of alfatoxin was assessed based on the Yeh et al. study from China in which both aflatoxin exposure and hepatitis B prevalence were measured. This study provides the best available information for estimating the carcinogenic risk posed by aflatoxin to the U.S. population. Cancer potency of aflatoxin was estimated using a biologically motivated risk assessment model. The best estimate of aflatoxin potency was 9 (mg/kg/day)⁻¹ for individuals negative for hepatitis B and 230 (mg/kg/day)⁻¹ for individuals positive for hepatitis B.     

Canadian immigration policy: state strategies and the quest for legitimacy

Selon les auteurs de cette communication, les données tirées d'entrevues avec les décideurs et de l'observation participante au processus d'élaboration des politiques militent en faveur d'une interprétation de la politique canadienne de l'immigration qui s'articule autour du rǒle de l'État. Pour eux, l'État est une entitéà double visage, à la fois puissante et vulnérable, et c'est ce caractère double qui conditionne les tendances actuelles en matière de politique de l'immigration. En élaborant sa politique, l'État cherche activement à accroǐtre sa propre légitimité en adoptant des mesures susceptibles de protéger une économie en difficulté, d'éviter les critiques sur la place publique et d'atténuer les conflits sociaux. L'état vise à assurer son hégémonie, en partie grǎce à un dialogue proactif destiné d'une part à recueillir de l'information et à mesurer les appuis et les oppositions, et d'autre part à contrǒler les divers groupes d'intérět. Ainsi, l'État est maǐtre du champ de l'élaboration des politiques, mais c'est un maǐtre qui se méfie des forces politiques qui pourraient miner sa légitimité. D'après les recherches des auteurs, les nouveaux intervenants, dont les groupes ethniques, les organisations humanitaires et les provinces, jouent un rǒle de plus en plus important dans un domaine dominé par 1'État fédéral. Deux intervenants traditionnels, le mouvement ouvrier et le patronat, en sont Venus à des positions considérablement moins polarisées. Le terrain politique est donc mouvant et plutǒt instable en cette époque où les principaux intervenants, y compris l'État, tentent de se réorienter dans un contexte international en pleine mutation. Data from interviews with policy actors and from participant observation of recent policy process support a particular state-centred interpretation of Canadian immigration policy. The state has a Janus-faced character - both powerful and vulnerable - and it is this ‘both-and’ feature which underlies current trends in immigration policy. Findings in this paper indicate that, in developing immigration policy, the state actively seeks to garner support for its own legitimacy by pursuing measures which will shore up the economy, avoid public criticism and mediate social conflict. The state is engaged in a hegemonic project involving a pro-active dialogue to gather information, to monitor support and opposition, and to attempt to control diverse interest groups. In sum, the state is both in control of the policy field and yet wary of political forces which potentially threaten its legitimacy. Our research shows that new social actors -ethnic groups, humanitarian organizations, the provinces - have come to play a more prominent role, within a field dominated by the federal state. Two traditional actors, labour and capital, have moved to less polarized views. The policy arena is shifting and prone to be unstable, as the key actors involved, including the state, struggle to come to terms with a changing global context.     

Seizing the means of reproduction: An illegal feminist abortion collective—How and why it worked

This paper describes an illegal feminist abortion collective [the Service] through whose efforts 11,000 abortions were performed between 1969 and 1973 when abortion was legalized. An analysis of interviews from 32 members of this lay group indicates how and why the collective was so effective in providing what is usually a physician-controlled medical procedure. After describing the structure of the organization and the process by which women obtained the abortion, including pre-abortion counseling and post-abortion follow-up, two sets of reasons for the collective's effectiveness are presented. The first five reasons derive from the interview themselves; they deal with the organization's social and historical context, its illegality, its charismatic leaders, its member satisfaction and its financial self-sufficiency. The next nine reasons deal with factors that make The Service a relatively typical democratic collective organization. The most important of these factors is its lack of concern for organizational survival per se. This account supports the Rothschild-Whitt model for collective democratic organizations. It also suggests that counseling is important both for the providers and for the receivers of abortions.     

A Flexible Evaluative Framework for Order Picking Systems

This paper develops a novel framework to evaluate the integral performance of order picking systems with different combinations of storage and order picking policies. The warehousing literature on order picking mostly considers minimizing either elapsed time or distance as the sole objective, whereas warehouse managers in a supply chain have to look beyond single‐dimensional performance and consider trade‐offs among different criteria. Thus managers still need a unified and efficient framework to select a portfolio of appropriate order picking policies from a multi‐criteria and contextual perspective. Our framework—combining data envelopment analysis, ranking and selection, and multiple comparisons—provides an efficient methodology to simultaneously analyze several interrelated problems in order picking systems with multiple performance attributes, such as service levels and operational costs. We demonstrate our approach through comprehensive evaluations of order picking policies in three low‐level, picker‐to‐parts rectangular warehouses facing demand variations.     

Optimal Planning Quantities for Product Transition

The replacement of an existing product with a new one presents many challenges. In particular, uncertainties in a new product introduction often lead to extreme cases of demand and supply mismatches. This paper addresses inventory planning decisions for product upgrades when there is no replenishment opportunity during the transition period. We allow product substitution: when a company runs out of the old product, a customer may be offered the new product as a substitute. We show that the optimal substitution decision is a time‐varying threshold policy and establish the optimal planning policy. Further, we determine the optimal delay in a new product introduction, given the initial inventory of the old product.