PLUG-IN ESTIMATION OF GENERAL LEVEL SETS

Given an unknown function (e.g. a probability density, a regression function, …) f and a constant c, the problem of estimating the level set L(c) ={f≥c} is considered. This problem is tackled in a very general framework, which allows f to be defined on a metric space different from . Such a degree of generality is motivated by practical considerations and, in fact, an example with astronomical data is analyzed where the domain of f is the unit sphere. A plug‐in approach is followed; that is, L(c) is estimated by L_n(c) ={f_n≥c} , where f_n is an estimator of f. Two results are obtained concerning consistency and convergence rates, with respect to the Hausdorff metric, of the boundaries ?L_n(c) towards ?L(c) . Also, the consistency of L_n(c) to L(c) is shown, under mild conditions, with respect to the L₁ distance. Special attention is paid to the particular case of spherical data.     

Just-in-time purchasing: an empirical study of operational practices, supplier development and performance

This paper examines the role of supplier development in establishing and managing efficient buyer–supplier operational links. The paper develops and assesses a measurement instrument for “operational” and “supplier development” just-in-time purchasing practices, followed by an examination of the relationships between the two sets, and an investigation into whether the use of “operational” and “supplier development” practices has a bearing on higher plant performance. A plant-level survey was carried out on a sample of electronics and machinery plants. The study empirically:

• documents the close connection between the buyer–supplier operational link and the buyer’s practices for supplier development;

• demonstrates that recourse to supplier development programs and their nature depend on the kind of vendor–vendee operational connection;

• test whether different plant performance outcomes result from the implementing of different “operational” and “supplier development” practices. It demonstrates that better-performing plants exhibit more advanced design and logistic links with sources, more formalised vendor-rating and ranking procedures, greater use of organisational devices for supplier-organisational integration and place greater importance on supplier assistance and training.

Plurality of Worlds, Plurality of Risks

Risk management decisions are not made only on the basis of expert risk assessment. In numerous instances, public controversy erupts, questioning the results of previous risk assessment procedures and shaping the development of risk management episodes. This article presents a case study of risk management in the context of a 1980s controversy over aerial spraying against a spruce budworm epidemic in Quebec and draws some general conclusions concerning the relationship between risk analysis and public controversies. Actors in public controversies define risks more broadly than risk assessment experts. Moreover, public controversies only partly concern issues of risk. They are first and foremost debates about social choices in which actors carry with them a multidimensional social experience of technology, trust, credibility and decision-making institutions. This experience contributes to the construction of a plurality of emergent representations of what is at stake in a controversy, referred to in this paper as "worlds of relevance." Analysis shows that in any given public controversy, there are not just two parties arguing against each other. Rather, several "worlds of relevance" can be found that link, in a variety of ways, a variety of entities not necessarily shared by all these worlds. Each "world of relevance" presents a different definition of what the issues and the stakes of the controversy are. Risks are only part of the picture, and they are embedded in "worlds of relevance" from which they take their significance. The successful management of a controversy entails the association of entities from different worlds.     

Money, real output, and deficit effects of coffee booms in Colombia

This paper develops a Vector Error Correction (VEC) model and uses the recently developed technique of ‘generalized’ impulse response analysis to test the empirical relationships in the Colombian economy between coffee revenues and a set of macro variables. We find that coffee price (revenue) shocks have exerted an important influence on money growth, inflation, and real exchange rates, and the direction of these effects are in line with some of the predictions of traditional Dutch Disease type models. The major difference between our results and the results of Dutch Disease type models arise in the effects of coffee booms on real output. We find that in the time horizon of 5 years after the boom, real output has increased in response to the effects of the coffee boom. The finding that coffee booms can result in positive long-run output effects is an important finding since it contradicts the traditional conclusion of Dutch Disease type models which envision an adverse long-run effect on output. We also find that the long-run effect of coffee booms is to reduce both current account and government deficits. These results illustrate strikingly that the term “Dutch Disease” is an unfortunately pejorative term that obscures the fact that coffee booms need not be viewed as a “disease” but as an extraordinary opportunity to strengthen internal and external balances.     

Compatible prior distributions for directed acyclic graph models

Summary.  The application of certain Bayesian techniques, such as the Bayes factor and model averaging, requires the specification of prior distributions on the parameters of alternative models. We propose a new method for constructing compatible priors on the parameters of models nested in a given directed acyclic graph model, using a conditioning approach. We define a class of parameterizations that is consistent with the modular structure of the directed acyclic graph and derive a procedure, that is invariant within this class, which we name reference conditioning.     

On the sustainability of bargaining solutions in family decision models

This paper analyses the sustainability of family bargaining agreements by developing a non-cooperative game between two spouses with symmetric preferences. To that end, we develop, by using a general utility function, a repeated non-cooperative game involving two players with symmetric preferences, where the characterization of a Nash sub-game perfect equilibrium allows us to demonstrate that the spouse with the greater bargaining power has a greater incentive to reach an agreement. This result is also reproduced by using a particular example of linear preferences in consumption. However, the influence of the bargaining power on the sustainability of a bargaining solution depends on the specification of the individual preferences, as well as the degree of altruism between the spouses.

Quantifying Littered Cigarette Butts to Measure Effectiveness of Smoking Bans to Building Perimeters

Abstract

Objective: The authors estimated the number of violations of a university policy that prohibited smoking within 25 ft of all campus buildings. Participants: The project was conducted by 13 student researchers from the university and a member of the local public health department. Methods: Students quantified cigarette butts that were littered in a 30-day period inside the prohibited smoking area of 7 campus buildings (large residential hall, small residential hall, administrative building, 2 academic buildings, campus cafeteria, and student union). Results: Investigators found a total of 7,861 cigarette butts (large residential hall: 1,198; small residential hall: 344; administrative building: 107; 2 academic buildings: 1,123 and 806; campus cafeteria: 2,651; and student union: 1,632). Conclusions: Findings suggest that there is low compliance with the university's smoking policy. The described project may be repeated by students at other universities as a method to advocate for policy change.     

Mandatory Testing of Drivers on the Basis of Age and Degenerative Diseases: Stakeholder Opinions

Concerns about the driving competence of older drivers have led to policy discussions about mandatory aged-based and disorder-based assessments. This study explored the attitudes, beliefs, and preferences of older adults, law enforcement officers, and licensing authorities toward reexamination of driving skills for persons with Alzheimer's disease (AD) and Parkinson's disease (PD) and at varying ages. With few exceptions, participants across all groups supported retesting drivers with AD. Moderate support was given for further evaluation of 90-year-olds and those with PD. Least endorsement was given for reassessment of 70-year-old drivers. Findings have implications for legislative changes to address drivers with AD and PD and at older ages.