Benchmark Calculations in Risk Assessment Using Continuous Dose-Response Information: The Influence of Variance and the Determination of a Cut-Off Value

A benchmark dose (BMD) is the dose of a chemical that corresponds to a predetermined increase in the response (the benchmark response, BMR) of a health effect. In this article, a method (the hybrid approach) for benchmark calculations from continuous dose-response information is investigated. In the formulation of the methodology, a cut-off value for an adverse health effect has to be determined. It is shown that the influence of variance on the hybrid model depends on the choice of determination of the cut-off point. If the cut-off value is determined as corresponding to a specified tail proportion of the control distribution, P(0), the BMD becomes biased upward when the variance is biased upward. On the contrary, if the cut-off value is directly determined to some level of the continuous response variable, the BMD becomes biased upward when the variance is biased downward. A simulation study was also performed in which the accuracy and precision of the BMD was compared for the two ways of determining the cut-off value. In general, considering BMRs of 1, 5, and 10% (additional risk) the precision of the BMD became higher when the cut-off value was estimated by specifying P(0), relative to the case with a direct determination. Use of the square-root of the maximum-likelihood estimator of the variance in BMD estimation may provide a bias that is reflected by the cut-off formulation (downward bias if specifying P(0), and upward bias if specifying the cut-off, c, directly). This feature may be reduced if an unbiased estimator of the standard deviation is used in the calculations.     

Paas,T., Tafenau E. (eds.): Modelling the Economies of the Baltic Sea Region

Review of Journals and Books

Paas, T., Tafenau E. (eds.): Modelling the Economies of the Baltic Sea Region     

The Role of Family and Friends in Return Migration and Its Labor Market Outcomes

Population Research and Policy Review - Drawing on survey data on individuals’ motives for migration in Sweden (N?=?2172), we examine the importance of family and friends for...     

Impacts of Return Migration on Rural U.S. Communities

Rural population loss is caused as much by low in‐migration as by high out‐migration, and for geographically disadvantaged nonmetropolitan counties in the United States, return migration plays a crucial role. This research captures impacts of return migrants on population, economy, and society in declining rural U.S. communities using a qualitative, multisited approach. Interviews conducted at high school reunions with rural returnees in their late 20s to late 40s show that the vast majority of returnees brought spouses and children back with them, increasing the short‐term and long‐term population. They also brought back much needed human capital, including education, job skills, and life experiences, and filled professional positions that are often hard to fill in rural communities. Entrepreneurial activities and self‐employment of many return migrants favorably affected rural economies by improving the employment base and expanding available services. Interviews show how decisions to move back were grounded in social relations that promoted civic engagement. While they mainly moved back for their children and their families, return migrants valued involvement in familiar social networks and the opportunities to make a difference in their rural hometowns.     

Progression of functional limitations in relation to physical activity: a life course approach

In this minireview, we summarize the research results to date on the progression of functional limitations and the role of physical activity during the life course in preventing risk factor accumulation. In addition, socioeconomic and health disparities play a role in the development process of functional limitation throughout life. We discuss the potential role of physical activity in alleviating this process. Functional limitations usually develop gradually over an extended period of time while the level of physical functioning varies greatly already from midlife onwards. Current research strongly suggests that physical activity has a beneficial effect on functional limitations at different life stages on the population level. However, the potential impact of physical activity in alleviating the effects caused by socioeconomic disparities is inconsistent. Research findings are also conflicting on the extent of the effect of physical activity among certain subsets of the population, such as obese persons. Although the benefits of physical activity on physical impairments and functioning among the adult population have been confirmed, the number of adults who are physically active is too low and, for the majority, physical activity declines with older age. Thus, detailed research evidence is needed for designing effective preventive interventions starting from earlier ages and continuing throughout the lifespan across different subgroups in the population.     

Mit beiden Augen sieht man besser

In this article the author is discussing the characteristics and differences of expert consultation and process consultation. After deducting the necessity of an integrated approach, the author describes the key success factors of a synthesis and the resulting added-value for the client. Selected case studies show the substantial enrichment of expert consultation through process consultation and vice versa.     

Identifying and Structuring the Objectives of Terrorists

The risk of terrorism is of great concern to many countries and significant resources are spent to counter this threat. A better understanding of the motivation of terrorists and their reasons for selecting certain modes and targets of attack can help improve the decisions to allocate resources in the fight against terrorism. The fundamental question addressed in this article is: “What do terrorists want?” We take the view that terrorists’ preferences for actions are based on their values and beliefs. An important missing piece in our knowledge of terrorists’ preferences is an understanding of their values. This article uses a novel approach to determine these values and state them as objectives, using principles from decision analysis and value‐focused thinking. Instead of interviewing decisionmakers and stakeholders, as would be normal in decision analysis, we extract the values of terrorists by examining their own writings and verbal statements. To illustrate the approach, we extract the values of Al‐Qaeda and structure them in terms of strategic, fundamental, and means objectives. These objectives are interrelated through a means‐ends network. This information is useful for understanding terrorists’ motivations, intent, and likely actions, as well as for developing policies to counter terrorism at its root causes.