Interpreting semilogarithmic regression coefficients in labor research

Labor economists frequently misinterpret coefficients of variables in semilogarithmic regression equations. The proportional rates of change in the dependent variable that are implied by these coefficients are often erroneously assumed to be valid over arbitrarily large intervals. This note provides mathematical and empirical evidence on how serious the error can be. A simple formula is developed for making correct interpretations of semilog regression coefficients. The authors thank David Greenaway for helpful comments.     

Measuring the probability of patch detection for four spatial sampling designs

In this paper, we derive the probabilities that four chosen sampling schemes will detect a circular patch of organisms whose location is at some random location in the study area. We also describe simulations which indicate the variation of patch detection probabilities for different realizations of the sampling design. We comment briefly on how probabilities would be affected by multiple and different shaped patches. Our results are a useful guide for practitioners when choosing a design and an appropriate sampling intensity.     

Ecological regression analysis of environmental benzene exposure and childhood leukaemia: sensitivity to data inaccuracies, geographical scale and ecological bias

Benzene is classified as a group 1 human carcinogen by the International Agency for Research on Cancer, and it is now accepted that occupational exposure is associated with an increased risk of various leukaemias. However, occupational exposure accounts for less than 1% of all benzene exposures, the major sources being cigarette smoking and vehicle exhaust emissions. Whether such low level exposures to environmental benzene are also associated with the risk of leukaemia is currently not known. In this study, we investigate the relationship between benzene emissions arising from outdoor sources (predominantly road traffic and petrol stations) and the incidence of childhood leukaemia in Greater London. An ecological design was used because of the rarity of the disease, the difficulty of obtaining individual level measurements of benzene exposure and the availability of data. However, some methodological difficulties were encountered, including problems of case registration errors, the choice of geographical areas for analysis, exposure measurement errors and ecological bias. We use a Bayesian hierarchical modelling framework to address these issues, and we investigate the sensitivity of our inference to various modelling assumptions.     

Uncertainty Quantification in the Ensemble Kalman Filter

The ensemble Kalman filter (EnKF) provides an approximate, sequential Monte Carlo solution to the recursive data assimilation algorithm for hidden Markov chains. The challenging conditioning step is approximated by a linear updating, and the updating weights, termed Kalman weights, are inferred from the ensemble members. The EnKF scheme is known to provide unstable predictions and to underestimate the prediction intervals, and even sometimes to diverge. The underlying cause for these shortcomings is poorly understood. We find that the ensemble members couple in the conditioning procedure and that the coupling increase multiplicatively in the recursive conditioning steps. Under reasonable Gauss‐independence assumptions, exact expressions for this correlation are developed. Moreover, expressions for the precision of the predictions and the downward bias in the empirical variance introduced in one conditioning step are found. These results are confirmed by a Gauss‐linear simulation study. Furthermore, we quantitatively evaluate an alternative, improved EnKF scheme on the basis of transformations of ensemble members under the same Gauss‐independent assumptions. The scheme is compared with the frequently used ensemble inflation scheme.     

Defining and Estimating the Scope of U.S. Faith-Based International Humanitarian Aid Organizations

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This study illuminates the size, scope, and impact of U.S. faith-based nonprofits in the international affairs sector....     

Psychosocial and Environmental Determinants of Eating Behaviors,Physical Activity,and Weight Change Among College Students: A Qualitative Analysis

Abstract

Objective: The goal of this study was to identify factors that college students perceived as contributing to healthy and unhealthy eating patterns, physical activity (PA) levels, and weight change. Participants: Forty-nine 18- to 22-year-old students at a midwestern university participated. Methods: Six focus groups (3 with each gender) were conducted, and data were analyzed using qualitative software to code and categorize themes and then reduce these to clusters according to commonly practiced methods of qualitative analysis. Results: Eating and PA behaviors appear to be determined by a complex interplay between motivations and self-regulatory skills as well as the unique social and physical environment comprising college life. Moreover, there appear to be gender differences in how these determinants impact behavior. Conclusions: Future research should examine these interactions in the college context in order to further our understanding of potential interventions or environmental modifications that support healthy eating and PA.     

Index insurance and climate risk management: Addressing social equity

Fair distribution of benefits from index insurance matters. Lack of attention to social equity can reinforce inequalities and undermine the potential index insurance holds as a tool for climate risk management that is also pro‐poor. The aims of this article are to: (a) examine social equity concerns raised by index insurance in the context of climate risk management, (b) consider how greater attention can be paid to social equity in index insurance initiatives, and (c) reflect on the policy challenges raised by taking social equity into account as a mechanism for climate risk reduction. The article draws on learning from the CGIAR's Research Program on Climate Change, Agriculture and Food Security (CCAFS) and presents the cases of the Index Based Livelihoods Insurance (IBLI) and Agriculture and Climate Risk Enterprise Ltd. (ACRE) in East Africa. It proposes a framework for unpacking social equity related to equitable access, procedures, representation and distribution within index insurance schemes. The framework facilitates identification of opportunities for building outcomes that are more equitable, with greater potential for inclusion and fairer distribution of benefits related to index insurance. The article argues that systematically addressing social equity raises hard policy choices for index insurance initiatives without straightforward solutions. Attention to how benefits and burdens of index insurance are distributed, suggests the unpalatable truth for development policy that the poorest members of rural society can be excluded. Nevertheless, a focus on social equity—facilitated by the framework—opens up opportunities to ensure index insurance is linked to more socially just climate risk management. At the very least, it may prevent index insurance from generating greater inequality. Taking social equity into account, thus, shifts the focus from agricultural systems in transition per se to systems with potential to incorporate societal transformation through distributive justice.     

Visual mediation of critical illness: an autobiographical account of nearly dying and nearly living1

This article is concerned with the portrayal of the impact of critical illness on the author's life. An autobiographical approach is used to illustrate how imagery mediates personal trauma. A personal journey over a four‐year period, from the onset of illness towards recovery, is portrayed in the form of snapshots of critical events. Running parallel to the visual dimension is the application of mountain climbing as a metaphor for first understanding critical illness and then as a vehicle to aid recuperation. The journey is described in a narrative style that represents one reality.