Methylmercury Risks and EPA + DHA Benefits Associated with Seafood Consumption in Europe

The intake of methyl‐Hg and EPA + DHA through consumption of seafood in Europe as well as the associated probability of exceeding the provisional tolerable weekly intake (PTWI) and the recommended daily intake (RDI), respectively, were estimated by combining methyl‐Hg and EPA + DHA contents in the five most consumed seafood species with hypothesized consumption distributions for eight European countries, chosen on the basis of size and representative significance. Two estimators were used: plug‐in (PI) and tail estimation (TE). The latter was based on the application of the extreme value theory to the intakes distribution curves. Whereas contents data were collected from own database and published scientific papers, consumption data were obtained from statistical sources of the various countries. Seafood consumption levels varied considerably between countries, from 140 in the United Kingdom to 628.5 g/(person.week) in Iceland. The main consumed species were also different between countries. The probability of exceeding the methyl‐Hg PTWI ranged from 0.04% in the United Kingdom to 9.61% in Iceland. Concerning the probability of exceeding the RDI of EPA + DHA, Iceland was third, after Portugal (66.05%) and Spain (61.05%) and the United Kingdom was the last (0.32%). While TE was most accurate for small probabilities, PI yielded best estimates for larger probabilities.     

Mapping the Timing,Pace, and Scale of the Fertility Transition in Brazil

Between 1960 and 2000, fertility fell sharply in Brazil, but this transition was unevenly distributed in space and time. Using Bayesian spatial statistical methods and microdata from five censuses, we develop and apply a procedure for fitting logistic curves to the fertility transitions in more than 500 small regions of Brazil over this 40‐year period. Doing so enables us to map the main features of the Brazilian fertility transition in considerable detail. We detect early declines in some regions of the country and document large differences between early and late transitions in regard to both the initial level of fertility and the speed of the transition. We also use our results to test hypotheses regarding changes in the level of development at the onset of the fertility transition and identify a temporary stall in the Brazilian transition that occurred in the late 1990s. A web site with project details is at http://schmert.net/BayesLogistic .     

Likelihood Elasticity and Error Bounds

In this note it is shown that the Fisher information can be related to elasticity, a very important concept in economics. This economic concept can be used to provide a more intuitive meaning of the Fisher information in some important situations.     

Describing extra-binomial variation with partially correlated models

Data in the form of proportions are often analyzed under a binomial model. However, because genuine random sampling is often infeasible, the subjects in the sample may be collected in clumps and the variances of the observed proportions may be considerably larger than those corresponding to the binomial model. A set of data from a study of the proportion of subjects testing positive to the disease toxoplasmosis is used in this article to motivate partially correlated binomial models capable of describing data observed in practical situations where clumped sampling is likely to appear, According to these models, the extra-binomial variance of the observed frequencies may range from a linear to a quadratic function of the sample size. An efficient algorithm for the evaluation of the resulting probability mass function is given.     

Space‐time cluster identification in point processes

The authors propose a new type of scan statistic to test for the presence of space‐time clusters in point processes data, when the goal is to identify and evaluate the statistical significance of localized clusters. Their method is based only on point patterns for cases; it does not require any specific knowledge of the underlying population. The authors propose to scan the three‐dimensional space with a score test statistic under the null hypothesis that the underlying point process is an inhomogeneous Poisson point process with space and time separable intensity. The alternative is that there are one or more localized space‐time clusters. Their method has been implemented in a computationally efficient way so that it can be applied routinely. They illustrate their method with space‐time crime data from Belo Horizonte, a Brazilian city, in addition to presenting a Monte Carlo study to analyze the power of their new test.     

Assessing Adjustment to Aging: A Validation Study for the Adjustment to Aging Scale (AtAS)

Adjustment to aging (AtA) is a multifactor adjustment process with implications on aging well among older adults. The aim of this study was to develop and validate a scale to assess the factors that older adults recognized as indicators of their AtA, with a cross-national comparative perspective towards aging well. Convenience sampling was used to gather questionnaire data, including demographics and the proposed scale. Complete data was available for 1,291 older community-dwelling adults, aged between 75 and 102 years (M = 83.9; SD = 6.68), who represented four different nationalities. Exploratory and confirmatory factor analyses were performed for dimension reduction and exploration of the factorial structure. Data gathered with the 22-items AtA five-factor scale showed overall good psychometric properties (in terms of distributional properties, statistical significant factor weights, factorial, convergent, discriminant criterion and external-related validities, as well as reliability). Five factors were selected for the Adjustment to Aging Scale: (a) sense of purpose and ambitions (b) zest and spirituality; (c) body and health; (d) aging in place and stability; and (e) social support. We present a 22-item scale with five factors for AtA estimation in a cross-national elderly population which produced valid and reliable data for elder persons from four different nationalities. Results showed that this scale is an adequate cross-cultural instrument for research, clinical practice and program development in the health care context. These may benefit from clearly understanding AtA as an important component for reducing health disparities and for aging well, across nationalities.     

Non‐Gaussian geostatistical modeling using (skew) t processes

We propose a new model for regression and dependence analysis when addressing spatial data with possibly heavy tails and an asymmetric marginal distribution. We first propose a stationary process with t marginals obtained through scale mixing of a Gaussian process with an inverse square root process with Gamma marginals. We then generalize this construction by considering a skew‐Gaussian process, thus obtaining a process with skew‐t marginal distributions. For the proposed (skew) t process, we study the second‐order and geometrical properties and in the t case, we provide analytic expressions for the bivariate distribution. In an extensive simulation study, we investigate the use of the weighted pairwise likelihood as a method of estimation for the t process. Moreover we compare the performance of the optimal linear predictor of the t process versus the optimal Gaussian predictor. Finally, the effectiveness of our methodology is illustrated by analyzing a georeferenced dataset on maximum temperatures in Australia.     

An Analysis of the Eco‐Efficiency of Remanufactured Personal Computers and Mobile Phones

Remanufacturing, long perceived as an environmentally friendly initiative, is supported by a number of governments. Yet, the assumption that remanufacturing is desirable to society has never been systematically investigated. In this paper, we examine the effectiveness and eco‐efficiency of remanufacturing in the personal computer and mobile phone industries. We investigate whether remanufacturing substantially reduces the environmental impact, as measured by cumulative energy demand (CED), generated over the life cycles (LCs) of these products, and the size of any reduction. We also examine the relative eco‐efficiency of remanufacturing compared with virgin manufacturing for these two products, where eco‐efficiency includes both willingness‐to‐pay (WTP) for the products as well as the energy consumed in producing the products. Our main findings are the following. One, remanufacturing is an effective way to reduce the total energy consumed during the LCs of personal computers and mobile phones, with one notable exception, when the life spans of remanufactured products are substantially shorter than the life spans of their new counterparts. Two, a remanufactured personal computer or mobile phone is not always more eco‐efficient than a corresponding new product. Three, the WTP for remanufactured personal computers and mobile phones, and consequently, their eco‐efficiencies, are a function of the prices of the correspondent new products at launch and years elapsed between launch and remanufacturing. Four, remanufactured units are sold at a discount relative to the price of new personal computers and mobile phones. Five, on the whole, the market for remanufactured mobile phones is more eco‐efficient than the market for new mobile phones. Six, the market for remanufactured computers is more eco‐efficient than the market for new computers. Lastly, because the group of remanufactured products is heterogeneous, not all remanufactured units are more eco‐efficient than the average new computer and mobile phone. We conclude with a discussion of the impact of our findings on European WEEE and WEEE‐like legislation.     

Recursive characterization of a large family of discrete probability distributions showing extra-Poisson variation

This article analyses the broad family of discrete probability distributions generated by relating Prob (y) to Prob (y?1), …, Prob (y?n), for some n≥1, through a recursive equation. This family contains the binomial, negative binomial and Poisson distributions as well as the Katz family of distributions. In addition, the suggested family contains some convolutions of Poisson distributions and other generalized distributions, which provide models for Poisson overdispersion or underdispersion.     

Application domains for the Delta method

The Delta method uses truncated Lagrange expansions of statistics to obtain approximations to their distributions. In this paper, we consider statistics Y=g(μ+X), where X is any random vector. We obtain domains 𝒟 such that, when μ∈𝒟, we may apply the distribution derived from the Delta method. Namely, we will consider an application on the normal case to illustrate our approach.