Mixture designs for five components in orthogonal blocks

The methods developed by John and Draper et al. of partitioning the blends (runs) of four mixture components into two or more orthogonal blocks when fitting quadratic models are extended to mixtures of five components. The characteristics of Latin squares of side five are used to derive rules for reliably and quickly obtaining designs with specific properties. The designs also produce orthogonal blocks when higher order models are fitted.     

Concentrating on the Worst Performers

There is a substantial variation in the quality of operators of nuclear power plants, and it is therefore widely believed that regulatory attention is best directed at the worst performers. What is not immediately apparent is a strategy for the optimal allocation of regulatory resources. We study a simple model for this problem, and find that, under reasonable assumptions, the optimal allocation does indeed behave as expected. The proper degree of unbalance, however, depends upon the effectiveness of regulation itself and on the variation among performers, ineffective regulation leading to more concentration on the bottom of the list and a net reduction in attention to the top. Not surprisingly, the optimal strategy is to press toward parity in risk, even if it means allowing some plants to become riskier. This strategy leads to a minimized net probability of accident anywhere.     

Estimation of Potential Health Effects from Acute Exposure to Hydrogen Fluoride Using a "Benchmark Dose" Approach

Communities across the United States are examining the manufacture, use, transport, and storage of hydrogen fluoride (HF) near residential areas as a consequence of a major release of HF in Texas in 1987. Reference exposure levels for routine and accidental HF emissions are calculated using existing animal and human data. The approach employs a logprobit extrapolation of concentration-response data to the 95% lower confidence limit on the toxic concentration producing a "benchmark dose" of 1% response (TC01), called a practical threshold. Species-specific and chemical-specific adjustment factors are applied to develop exposure levels applicable to the general public. Using this method, the 1-hr reference exposure level to protect the public against any irritation from a routine emission (REL-1) is 0.7 ppm and the level to protect against severe irritation from a once-in-a-lifetime (REL-2) release is 2 ppm. This approach is compared to a modified "uncertainty factor" approach.     

Statewide substance abuse prevention planning

The State of Rhode Island contracted with the authors to prepare a statewide, comprehensive substance abuse prevention plan. The literature review revealed a lack of research on statewide planning for prevention services. To obtain data for Rhode Island's plan, the authors conducted a family of studies including synthetic estimation, key informant interviews, a telephone survey of agency directors, program budget analysis, construction of a statistical index for estimating the optimal geographic allocation of prevention dollars, and a review of General Laws regarding tobacco, alcohol, and other drugs. Their recommendations include the increased funding and coordination of prevention services, allocating services according to need rather than population size, greater use of social policy as a prevention tool, and a shift in primary prevention programming from senior high to lower grades and in program emphasis from information-education to psychosocial programs.     

Estimation of group means in generalized linear mixed models

In this study, we investigate the concept of the mean response for a treatment group mean as well as its estimation and prediction for generalized linear models with a subject‐wise random effect. Generalized linear models are commonly used to analyze categorical data. The model‐based mean for a treatment group usually estimates the response at the mean covariate. However, the mean response for the treatment group for studied population is at least equally important in the context of clinical trials. New methods were proposed to estimate such a mean response in generalized linear models; however, this has only been done when there are no random effects in the model. We suggest that, in a generalized linear mixed model (GLMM), there are at least two possible definitions of a treatment group mean response that can serve as estimation/prediction targets. The estimation of these treatment group means is important for healthcare professionals to be able to understand the absolute benefit vs risk. For both of these treatment group means, we propose a new set of methods that suggests how to estimate/predict both of them in a GLMMs with a univariate subject‐wise random effect. Our methods also suggest an easy way of constructing corresponding confidence and prediction intervals for both possible treatment group means. Simulations show that proposed confidence and prediction intervals provide correct empirical coverage probability under most circumstances. Proposed methods have also been applied to analyze hypoglycemia data from diabetes clinical trials.     

Urban politics and the study of urban poverty: Promising developments and future directions

The study of urban poverty is alive and well in sociology. The study of urban politics, by contrast, has stagnated. Though scholars agree that politics shapes the creation and durability of urban poverty, analytical connections between the two subfields are rarely made explicit. In this article, I make the case for a more integrated body of research. I first illustrate how urban poverty scholars implicitly discuss politics, and conversely, how urban politics scholars implicitly discuss poverty. I then highlight recent developments in the literature and propose two paths forward—by no means the only paths forward, but two ways to jumpstart greater conversation across both subfields. For the urban poverty literature, a focus on organizations can help scholars analyze political dynamics more directly. And for the urban politics literature, an emphasis on political mechanisms rather than overarching perspectives can disrupt the current theoretical malaise. These two moves can advance both literatures while drawing them closer together.     

YOUR SECOND LIFE?

This article examines the performativity of intellectual property in digital gaming environments, with a focus on Massively Multi-Player On Line Games (MMOGs). The analysis centers on the creation and management of goodwill, an intangible asset of considerable value to corporations based on affective bonds between consumers, corporations, and their commodities in the marketplace. Most critical analyses of intellectual property consider neither the centrality of goodwill to corporate management of their intellectual properties in digital environments, nor the significance of the legal conditions that structure activity in such contexts. We develop a theoretical framework based on cultures of circulation involving network sociality, circuits of interactivity and the extensibility of the computer/user interface. This enables us to better understand shifting relations of power and reciprocity between corporations and consumers in digital gaming contexts, where the division between player-consumption and player-production is increasingly blurred. Technological capacities for consumers to become producers of gaming content changes the terrain upon which conflicts between corporations and consumers about intellectual property are negotiated and enhances the value of goodwill. An examination of Linden Lab's Second Life – one of the fastest growing MMOGs and the first to affirm players’ intellectual property rights in their digital creations – provides an illustration of both the limits and possibilities afforded by goodwill as a form of emerging governance in game worlds.