An extension of Horvitz–Thompson estimator used in adaptive cluster sampling to continuous universe

In this paper, an extension of Horvitz–Thompson estimator used in adaptive cluster sampling to continuous universe is developed. Main new results are presented in theorems. The primary notions of discrete population are transferred to continuous population. First and second order inclusion probabilities for networks are delivered. Horvitz–Thompson estimator for adaptive cluster sampling in continuous universe is constructed. The unbiasedness of the estimator is proven. Variance and unbiased variance estimator are delivered. Finally, the theory is illustrated with an example.     

A Probabilistic Arsenic Exposure Assessment for Children Who Contact CCA-Treated Playsets and Decks, Part 1: Model Methodology, Variability Results, and Model Evaluation

Concerns have been raised regarding the safety of young children who may contact arsenic residues while playing on and around chromated copper arsenate (CCA)-treated wood playsets and decks. Although CCA registrants voluntarily canceled the production of treated wood for residential use in 2003, the potential for exposure from existing structures and surrounding soil still poses concerns. The EPA's Office of Research and Development developed and applied the probabilistic Stochastic Human Exposure and Dose Simulation model for wood preservatives (SHEDS-Wood) to estimate children's absorbed dose of arsenic from CCA. Skin contact with, and nondietary ingestion of, arsenic in soil and wood residues were considered for the population of children in the United States who frequently contact CCA-treated wood playsets and decks. Model analyses were conducted to assess the range in population estimates and the impact of potential mitigation strategies such as the use of sealants and hand washing after play events. The results show predicted central values for lifetime annual average daily dose values for arsenic ranging from 10(-6) to 10(-5) mg/kg/day, with predicted 95th percentiles on the order of 10(-5) mg/kg/day. There were several orders of magnitude between lower and upper percentiles. Residue ingestion via hand-to-mouth contact was determined to be the most significant exposure route for most scenarios. Results of several alternative scenarios were similar to baseline results, except for the scenario with greatly reduced residue concentrations through hypothetical wood sealant applications; in this scenario, exposures were lower, and the soil ingestion route dominated. SHEDS-Wood estimates are typically consistent with, or within the range of, other CCA exposure models.     

Should occupational codes be obtained from census data or from retrospective survey data in studies on occupational health?

The aim of this study was to assess the quality of occupational history information obtained via retrospective interview questions by comparison with occupational information for the same individuals obtained via a number of censuses. Moreover, morbidity patterns were investigated for different occupational exposure categories that were constructed either on occupational data gathered retrospectively or on data gathered longitudinally through censuses. The study population consisted of 6764 men and 2104 women who were interviewed within the Swedish Survey on Living Conditions. Census data on occupation from 1960, 1970 and 1975 were used for comparison. There was high level of agreement between the two data bases for occupational categories containing workers who were stable in their occupations. The correspondence was better for women. Prevalence rates for different long-term illnesses were almost the same for the categories, no matter which of the data bases was used for constructing the categories. Thus, we have found that self-reported work histories might be a useful way of controlling for occupational exposures in the past.     

Towards Integrated Community Care for the Frail Aged

The growing awareness of family support among the frail aged has yet to be incorporated into a clear strategy for developing comprehensive community care. A starting point is to identify the characteristics of target populations, the range of tasks associated with aged care, and the capabilities of various informal and formal providers. Fully appropriate services would take into account the availability of family support as well as the needs of older people themselves. It is suggested that services be designed to (1) supplement support from spouses; (2) periodically substitute for other co-resident carers; (3) complement assistance from nonresident family; and (4) substitute for the unavailability of family support. Community services currently provide modest supplements, principally to nonresident support, but do little to address the other contexts of care. Suggestions are made for program developments that would provide genuine alternatives to institutionalisation without devolving the social costs entirely onto families.     

Good girls don't comment on politics? Gendered character of online political participation in the Czech Republic

The article aims to contribute to the still relatively unexplored area of the relationship between gender and online political participation. Using two complementary methods – a representative, post-election survey of the adult Czech population and a content analysis of communication on the selected Czech political parties’ Facebook profiles during the campaign for the 2013 Parliamentary Elections – we attempt to challenge some established assumptions regarding the allegedly equalizing effect of the Internet and social media on participatory behaviour of men and women. While survey data discovered subtle yet statistically significant differences between men and women in some online expressive activities on Facebook, mainly commenting on other users’ statuses, content analysis further revealed that there are not only notable gender gaps among the Facebook users who commented on the campaign, but also differences in the tone of communication produced by the respective gender groups, with men posting more negative comments addressed to parties as well as to other Facebook users. We suggest that these results question the prevailing perception about the narrowing of the ‘gender gap’ in the online environment and call for a more nuanced methodological approach to different forms of online political expression.     

SENSITIVITY ANALYSIS OF THE STOCHASTIC GROWTH RATE: THREE EXTENSIONS†

The perturbation analysis of population growth rate plays an important role in population biology. The sensitivity and/or elasticity (proportional sensitivity) of population growth rate to changes in the vital rates are regularly used (i) to predict the effects of environmental perturbations, (ii) to characterize selection gradients on life‐history traits, (iii) to evaluate management tactics, (iv) to analyse life table response experiments, and (v) to calculate the sampling variance in population growth rate. In a stochastic environment, population growth is described by the stochastic growth rate, which gives, with probability 1, the asymptotic time‐averaged growth rate of any realization. Tuljapurkar derived the sensitivity and elasticity of the stochastic growth rate to changes in the entries of the stochastic matrices. This paper extends his result to cover three cases, each of which has arisen recently in applications. The first gives the response of the stochastic growth rate to environment‐specific perturbations, applied only in a specified subset of the possible environments. The second gives the sensitivity and elasticity of the stochastic growth rate to changes in lower‐level parameters. The third applies to stochastic seasonal models, in which the projection matrix for each year is a periodic product of matrices describing seasonal transitions. In this case interest focuses on the sensitivity of the stochastic growth rate to changes in the entries of the seasonal matrices, not entries in the annual matrices. The paper describes examples of problems where each of these extensions is needed, and the algorithms for each of the new calculations.