Robustness of Risk Maps and Survey Networks to Knowledge Gaps About a New Invasive Pest

In pest risk assessment it is frequently necessary to make management decisions regarding emerging threats under severe uncertainty. Although risk maps provide useful decision support for invasive alien species, they rarely address knowledge gaps associated with the underlying risk model or how they may change the risk estimates. Failure to recognize uncertainty leads to risk‐ignorant decisions and miscalculation of expected impacts as well as the costs required to minimize these impacts. Here we use the information gap concept to evaluate the robustness of risk maps to uncertainties in key assumptions about an invading organism. We generate risk maps with a spatial model of invasion that simulates potential entries of an invasive pest via international marine shipments, their spread through a landscape, and establishment on a susceptible host. In particular, we focus on the question of how much uncertainty in risk model assumptions can be tolerated before the risk map loses its value. We outline this approach with an example of a forest pest recently detected in North America, Sirex noctilio Fabricius. The results provide a spatial representation of the robustness of predictions of S. noctilio invasion risk to uncertainty and show major geographic hotspots where the consideration of uncertainty in model parameters may change management decisions about a new invasive pest. We then illustrate how the dependency between the extent of uncertainties and the degree of robustness of a risk map can be used to select a surveillance network design that is most robust to knowledge gaps about the pest.     

A Model for Setting Performance Objectives for Salmonella in the Broiler Supply Chain

A stochastic model for setting performance objectives for Salmonella in the broiler supply chain was developed. The goal of this study was to develop a model by which performance objectives for Salmonella prevalence at various points in the production chain can be determined, based on a preset final performance objective at the end of the processing line. The transmission of Salmonella through the broiler production chain was modeled. The prevalence at flock level was calculated from the measured prevalence at sample level. The transmission model is based on data on the occurrence of Salmonella collected in the Dutch broiler production chain during several years. The developed model can be used by policymakers and industry to determine economically and politically acceptable performance objectives for various points of the production chain and to draw conclusions about which interventions are most appropriate.     

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.     

Scheduling Truck Arrivals at an Air Cargo Terminal

We consider the scheduling of truck arrivals at an air cargo terminal. By coordinating arrivals of cargo delivery trucks with outbound flight departure schedules, some of the shipments can be transferred directly to the departing flights, while others will be stored at the terminal's storage facility and incur extra handling and storage costs. The objective is to obtain a feasible schedule so as to minimize the total cost of operations. We formulate the problem as a time‐indexed integer program and show that, even with limited number of unloading docks at the terminal, the problem is non‐trivial (NP‐hard in the strong sense). Our solution method includes an exact solution procedure to determine an optimal unloading sequence for the shipments carried by each truck, together with a Lagrangian relaxation‐based heuristic for assigning trucks to truck docks and determining truck arrival times. We conducted computational experiments to test the performance of our solution method. Computational results show that our method can generate near‐optimal solutions efficiently. Our simulation results indicate that the scheduling approach proposed in this paper has the potential to generate significant cost savings over a first‐come, first‐served approach currently used at the air cargo terminal that we observed.     

Competitive Strategies and Firm Performance: a Comparative Analysis of Pure,Hybrid and ‘Stuck‐in‐the‐middle’ Strategies in Spanish Firms

The purpose of this study was to examine the viability of hybrid competitive strategies, which combine differentiation and cost elements, and their impact on organizational performance in comparison to pure strategies and ‘stuck‐in‐the‐middle’ combinations. Previous studies have focused above all on US data. The analysis carried out in this paper has centred on a multisectorial sample of 164 Spanish firms. The findings show that a large number of the organizations use different types of hybrid strategies and also that such strategies tend to be associated with higher levels of firm performance, particularly those strategies which place emphasis on a greater number of strategic dimensions, and specifically on innovation differentiation.     

Bringing About Changes to Corporate Social Policy through Shareholder Activism: Filers,Issues, Targets,and Success

We examine shareholder initiated social policy proposals' capacity to exert pressure on management to force it to adopt the suggested changes in policy. We show that social proposals, filed under the U.S. Securities and Exchange Commission's Rule 14a‐8, have a more limited capacity to change corporate social policy than it has been previously reported. However, the capacity to exert pressure on firms can be substantially higher for some types of filers, notably pension funds and mutual funds. The analysis also suggests that the capacity to influence management is higher for some types of issues presented in the resolution, such as those related to board diversity, energy and environment, and international laborand human rights. We also provide suggestions explaining why shareholder activism is a persistent practice despite its limited results.     

Does Ownership Form Matter for Corporate Social Responsibility? A Longitudinal Comparison of Environmental Performance between Public,Private, and Joint‐venture Firms

This study examines whether a firm's ownership form has any influence on its social performance. Conventional wisdom suggests that public (publicly traded) corporations are more susceptible to corruption and socially irresponsible behavior than privately owned corporations because of the intense short‐term profit maximization pressure from shareholders and the lack of sufficient monitoring mechanisms. This study introduces an alternate perspective in thinking about the relationship between ownership form and corporate social responsibility. This study reasons that public corporations are more likely to become socially responsible because of their greater exposure to external influence and greater dependence on external actors with diverse interests. Using a panel data on the pollution management practices of 118 industrial facilities over a 13‐year period, this study shows that public corporations were indeed subject to greater external pressure to reduce pollution, and the pressure led to consistently stronger environmental performance.     

LINGUISTIC DIVERSITY AND REDISTRIBUTION

This paper investigates the effect of linguistic diversity on redistribution in a broad cross‐section of countries. We use the notion of “linguistic distances” and show that the commonly used fractionalization index, which ignores linguistic distances, yields insignificant results. However, once distances between languages are accounted for, linguistic diversity has both a statistically and economically significant effect on redistribution. With an average level of redistribution of 9.5% of GDP in our data set, an increase byone standard deviation in the degree of diversity lowers redistribution by approximately one percentage point. We also demonstrate that other measures, such as polarization and peripheral heterogeneity, provide similar results when linguistic distances are incorporated. (JEL: D6, D74, H5, Z10)     

The Microeconomics of Efficient Group Behavior: Identification1

Consider a group consisting of S members facing a common budget constraint p'ξ=1: any demand vector belonging to the budget set can be (privately or publicly) consumed by the members. Although the intragroup decision process is not known, it is assumed to generate Pareto‐efficient outcomes; neither individual consumptions nor intragroup transfers are observable. The paper analyzes when, to what extent, and under which conditions it is possible to recover the underlying structure—individual preferences and the decision process—from the group's aggregate behavior. We show that the general version of the model is not identified. However, a simple exclusion assumption (whereby each member does not consume at least one good) is sufficient to guarantee generic identifiability of the welfare‐relevant structural concepts.