Rainfall or price variability: what determines rangeland management decisions? A simulation-optimization approach to South African savannas

Savannas cover the greater part of Africa and Australia and almost half of South America and contribute to the livelihoods of more than 350 million people. With the intensification of land use during the second half of the 20th century, savannas have become increasingly degraded through bush encroachment as a consequence of increased grazing pressure. Research on rangeland dynamics, however, provides contradicting answers with regard to the causes and possible remedies of bush encroachment. In this article we present results from an application of a simulation-optimization model to the case of extensive rangeland management in South Africa. Our model differs from previous approaches in that it explicitly accounts for the influence of stochastic prices and rainfall on economically optimal management decisions. By showing the implications of neglecting price variation and stochasticity in rangeland models we provide new insights with regard to the determinants of bush encroachment and rangeland managers' economic return. We demonstrate that, in the case of South Africa, optimal rangeland management is likely to lead to bush encroachment that eventually makes livestock holding unprofitable. Yet, we identify the costs of fire management to be a limiting factor for managers to counteract bush encroachment and explore the impact of policy measures to reduce fire control costs on the ecological and economic sustainability of livestock holding.     

Forecast performance of WASDE price projections for U.S. corn

We conduct a comprehensive evaluation of the season‐average price projections for U.S. corn as published by the U.S. Department of Agriculture's World Agricultural Supply and Demand Estimates (WASDE), an important issue given reduced resources and increased program scrutiny within the Federal Government. This study is the first in the literature to evaluate the WASDE corn projections relative to futures adjusted forecasts throughout the forecasting cycle using a lengthy evaluation period (1980/81–2012/13). We find that WASDE projections provide lower RMSEs relative to futures adjusted forecasts for 9 of the 16 forecast periods, 4 of which are statistically different. Encompassing tests show that WASDE projections often provide incremental information not present in the futures adjusted forecasts. Composite forecasts based on futures adjusted forecasts and WASDE projections reduced the RMSEs over all forecast periods by an average 12–16%. Favorable average trading profits may be generated for some forecast months using WASDE projections. Overall, our results suggest that WASDE projections of the U.S. corn season‐average price provide useful information to the market and could enhance the efficiency of the agricultural sector.     

Understanding applicant behavior in employment interviews: A theoretical model of interviewee performance

The purpose of this article is to present a theoretical model of interviewee performance in selection interviews. Our model positions the construct of interviewee performance as a central mediating variable between candidate attributes and interviewer ratings. The model includes six sets of factors that may influence interviewee performance, interviewer ratings, or both (e.g., interviewer–interviewee dynamics). This model promotes a fundamental shift in the way we think about employment interviews, from a focus on interviewer ratings to a focus on interviewee performance. Factors like culture and interview specific self-efficacy, while receiving little attention in current literature, take on greater significance when viewed through the lens of interviewee performance. A number of avenues for future research are developed and presented, which we hope will encourage future research in this area.     

Making Benefit Transfers Work: Deriving and Testing Principles for Value Transfers for Similar and Dissimilar Sites Using a Case Study of the Non-Market Benefits of Water Quality Improvements Across Europe

We implement a controlled, multi-site experiment to develop and test guidance principles for benefits transfers. These argue that when transferring across relatively similar sites, simple mean value transfers are to be preferred but that when sites are relatively dissimilar then value function transfers will yield lower errors. The paper also provides guidance on the appropriate specification of transferable value functions arguing that these should be developed from theoretical rather than ad-hoc statistical approaches. These principles are tested via a common format valuation study of water quality improvements across five countries. While this provides an idealised tested, results support the above principles and suggest directions for future transfer studies.     

Conflicting tasks and moral hazard: Theory and experimental evidence

We study a multi-task principal-agent problem in which tasks can be in direct conflict with each other. In theory, it is difficult to induce a single agent to exert efforts in two conflicting tasks, because effort in one task decreases the success probability of the other task. We have conducted an experiment in which we find strong support for the relevance of this incentive problem. In the presence of conflict, subjects choose two efforts significantly less often when both tasks are assigned to a single agent than when there are two agents each in charge of one task.     

Saving babies? Revisiting the effect of very low birth weight classification

We reconsider the effect of very low birth weight classification on infant mortality. We demonstrate that the estimates are highly sensitive to the exclusion of observations in the immediate vicinity of the 1,500-g threshold, weakening the confidence in the results originally reported in Almond, Doyle, Kowalski, and Williams (2010).     

The recession's effect on hospital registered nurse employment growth

Recessions are not uncommon in the United States, but the most recent recession is arguably the most severe economic downturn since the Great Depression of the 1930s. Although recessions result in increases in national unemployment in most sectors of the economy, they have resulted in increases in registered nurse (RN) employment as many non-working married RNs re-enter the workforce when their spouses lose their jobs. Over the past decade, hospital RN employment increased by more than 400,000 with virtually all of this growth associated with the two recessions that occurred during this period. The most recent recession led to an increase in hospital RN employment that was not only unprecedented in size, estimated at nearly 250,000, but was marked by the employment of large numbers of RNs over 50 years of age. While national unemployment rates remain high, hospitals should prepare for an eventual jobs recovery when many RNs are likely to leave the workforce.     

新环境下投资思维的转变

随着QE2的推出,欧债危机的进一步扩散,中东地区的不稳定事件,以及我国面临经济转型,国际国内形势更加错综复杂。2010年上证指数的萎靡而中小创业板的活跃,使多数投资者转变为概念炒作。追涨杀跌。2011年,权重股的价值回归而中小创业板的一路下跌,使多数投资者的收益大幅缩水。在这新环境下,通过分析各因素对我国A股市场的影响,得出结论：投资者应适时转变投资思维,采取价值投资并结合技术分析进一步扩大收益。     

The impact of the amount of available information on decision delay: The role of common features

In two studies, we show that features shared by products (common features) do not cancel out during the decision-making process but in fact are consequential as they decrease desire for delay in decision making. In study 1, we show that as the amount of available information about product features increases, decision delay decreases in spite of the additional information being identical across the products. Further, we also find that this effect is partially mediated by information adequacy. In study 2, we show that despite the overall difficulty of making decisions under avoidance?Cavoidance versus approach?Capproach conflict, an increase in common features decreases decision delay under both conflict conditions.     

Empirical and Heuristic-Based Evaluation of Collaborative Modeling Systems: An Evaluation Framework

Within the field of groupware systems, collaborative modeling systems play an important role. They are useful and promising tools for many fields of application. In this paper we begin with the evaluation of the usefulness of one of these tools, SPACE-DESIGN, by applying it to a specific domain and by comparing it to a single-user tool which is shared by means of a shared window system. We have performed a study in two phases in order to evaluate usability aspects and the awareness support of both software tools. The first phase is an empirical study with users who have worked with both software tools, whilst the second is a heuristic study with some heuristic models that are well known in the context of the research work. Taking into account this study, we propose a complete evaluation framework, to be used as a theoretical lab which could be used to evaluate interactive and usability aspects of any collaborative modeling tool. This is based on a comparison strategy and proposes a specific sequence of phases: selection of collaborative modeling tools, empirical evaluation, heuristic evaluation, analysis of results, and obtaining of conclusions.