Proposed best practice for projects that involve modelling and simulation

Modelling and simulation has been used in many ways when developing new treatments. To be useful and credible, it is generally agreed that modelling and simulation should be undertaken according to some kind of best practice. A number of authors have suggested elements required for best practice in modelling and simulation. Elements that have been suggested include the pre‐specification of goals, assumptions, methods, and outputs. However, a project that involves modelling and simulation could be simple or complex and could be of relatively low or high importance to the project. It has been argued that the level of detail and the strictness of pre‐specification should be allowed to vary, depending on the complexity and importance of the project. This best practice document does not prescribe how to develop a statistical model. Rather, it describes the elements required for the specification of a project and requires that the practitioner justify in the specification the omission of any of the elements and, in addition, justify the level of detail provided about each element. This document is an initiative of the Special Interest Group for modelling and simulation. The Special Interest Group for modelling and simulation is a body open to members of Statisticians in the Pharmaceutical Industry and the European Federation of Statisticians in the Pharmaceutical Industry. Examples of a very detailed specification and a less detailed specification are included as appendices.     

EU Accession and Income Growth: An Empirical Approach

The dynamic effects from EU membership are crucial for the new member states to catch up with the average income level in the old member states. To gauge the dynamic effects we follow a two-step procedure in which a gravity equation for bilateral trade shows the trade effect of EU membership and a growth regression yields the income effect of trade. Shared EU membership is found to increase trade between two of its member states with about 27%. EU membership may contribute to trade by inducing countries to improve the quality of their institutions. Trade increases by another 23% if institutions improve, yielding a total trade increase of 50%. Improved openness increases income by 38% according to our estimates. Adding a small direct effect of improved institutions on income, the total income effect of EU membership is 40% for the 12 new members and Turkey. This implies that EU membership, or its effect on trade and institutions, could lead to large economic gains for the new member states, but does not bring them economically on par with the old member states.

Computational risk management techniques for fixed charge network flow problems with uncertain arc failures

We consider a formulation for the fixed charge network flow (FCNF) problem subject to multiple uncertain arc failures, which aims to provide a robust optimal flow assignment in the sense of restricting potential losses using Conditional Value-at-Risk (CVaR). We show that a heuristic algorithm referred to as Adaptive Dynamic Cost Updating Procedure (ADCUP) previously developed for the deterministic FCNF problem can be extended to the considered problem under uncertainty and produce high-quality heuristic solutions for large problem instances. The reported computational experiments demonstrate that the described procedure can successfully tackle both the uncertainty considerations and the large size of the networks. High-quality heuristic solutions for problem instances with up to approximately 200,000 arcs have been identified in a reasonable time.     

Organizational Effects on Race Relations in Schools

This article identifies organizational structures and practices in schools that influence the frequency of interracial interactions, the likelihood ofcross-race friendships, and students' attitudes and behaviors toward members of different racial and ethnic groups. These formal and informal organizational practices include curriculum tracking, assignment to classes, attendance at school level functions, and extracurricular activities. The article discusses how the quality of interracial interactions and the resultingrelationships among students is influenced by the contexts of these different organizational practices, including students' status expectations, cooperative versus competitive modes of academic and extracurricular interactions, and educators' views on racial/ethnic issues and their preferences for instructional methods. By taking these effects into account, schools can make significant advances in promoting positive race relations.     

Neither a Dinosaur Nor a Weathercock: The Construction of a Reputably Continuous Self in Czech Postcommunist Life Stories

This article explores an exemplary life story to show some of the ways in which men and women who had successful careers under communism attend to the potential stigma. It analyzes the overall life story as a structure of stories, reports, self-characterizations, and arguments, where the stories have an especially strategic significance. They are cultural stories (Miller and Glassner 1997) of the precommunist middle class; collective stories (ibid.) of communist-era professionalism; and continuity stories of revolution in local contexts.     

The implications of increased survivorship for mortality variation in aging populations

The remarkable growth in life expectancy during the twentieth century inspired predictions of a future in which all people, not just a fortunate few, will live long lives ending at or near the maximum human life span. We show that increased longevity has been accompanied by less variation in ages at death, but survivors to the oldest ages have grown increasingly heterogeneous in their mortality risks. These trends are consistent across countries, and apply even to populations with record-low variability in the length of life. We argue that as a result of continuing improvements in survival, delayed mortality selection has shifted health disparities from early to later life, where they manifest in the growing inequalities in late-life mortality.     

The use of geotechnologies for the identification of the urban flora in the city of Teresina,Brazil

Urban Ecosystems - Urban greenness is an element of vital importance for the population quality of life, and forest inventory is considered the most appropriate method for its assessment. Remote...