Inverse Adaptive Cluster Sampling with Unequal Selection Probabilities: Case Studies on Crab Holes and Arsenic Pollution

Adaptive cluster sampling is an efficient method of estimating the parameters of rare and clustered populations. The method mimics how biologists would like to collect data in the field by targeting survey effort to localised areas where the rare population occurs. Another popular sampling design is inverse sampling. Inverse sampling was developed so as to be able to obtain a sample of rare events having a predetermined size. Ideally, in inverse sampling, the resultant sample set will be sufficiently large to ensure reliable estimation of population parameters. In an effort to combine the good properties of these two designs, adaptive cluster sampling and inverse sampling, we introduce inverse adaptive cluster sampling with unequal selection probabilities. We develop an unbiased estimator of the population total that is applicable to data obtained from such designs. We also develop numerical approximations to this estimator. The efficiency of the estimators that we introduce is investigated through simulation studies based on two real populations: crabs in Al Khor, Qatar and arsenic pollution in Kurdistan, Iran. The simulation results show that our estimators are efficient.     

Causes and Consequences of the Divergent Working-Time Patterns of Employed Mothers in the UK and the US: Developing a Comparative Analysis

The paper aims to develop a framework to understand the variant use of part-time work by employed mothers in the UK and US. In particular, this paper seeks to explore how diversity in the use of part-time work can be explained when both countries are associated with a neo-liberal form of capitalism (Hall and Soskice, Varieties of Capitalism: the institutional foundations of comparative advantage, 2001) and welfare regime (Esping-Andersen, The three worlds of welfare capitalism, 1990). It is argued here that by combining aspects of the Varieties of Capitalism (VoC) and welfare regimes literatures with Gender Regime theory (Walby, Social Politics, 11(1):4–29, 2004), a gender centred analysis of both the causes and consequences of divergent working-time patterns can be more adequately achieved.

Sampling television programs for content analysis of sex on TV: how many episodes are enough?

Content analysis is widely used to analyze sexual themes and messages on television. Although researchers generally use a sampling procedure to identify programs for analysis, there is currently no gold standard for the number of episodes needed to establish a valid, representative sample. This study sought to explore how many episodes of weekly television programs should be examined for an accurate assessment of sexual content present throughout the season. Various sampling strategies were used to select episodes from programs that ran in the 1998-1999 season, and results were compared with data collected from all episodes of these programs to test representativeness. Findings suggest that to provide a representative assessment of sexual content on television programs for behavior-level variables, a random sample of five episodes of weekly television programs is sufficient, while three episodes may be acceptable if variation is minimal. A random sample of seven episodes is needed for character-based analyses.     

A review of research on women's use of violence with male intimate partners

This article provides a review of research literature on women who use violence with intimate partners. The central purpose is to inform service providers in the military and civilian communities who work with domestically violent women. The major points of this review are as follows: (a) women's violence usually occurs in the context of violence against them by their male partners; (b) in general, women and men perpetrate equivalent levels of physical and psychological aggression, but evidence suggests that men perpetrate sexual abuse, coercive control, and stalking more frequently than women and that women also are much more frequently injured during domestic violence incidents; (c) women and men are equally likely to initiate physical violence in relationships involving less serious "situational couple violence," and in relationships in which serious and very violent "intimate terrorism" occurs, men are much more likely to be perpetrators and women victims; (d) women's physical violence is more likely than men's violence to be motivated by self-defense and fear, whereas men's physical violence is more likely than women's to be driven by control motives; (e) studies of couples in mutually violent relationships find more negative effects for women than for men; and (f) because of the many differences in behaviors and motivations between women's and men's violence, interventions based on male models of partner violence are likely not effective for many women.     

Effect of certified personal trainer services on stage of exercise behavior and exercise mediators in female college students

OBJECTIVE: The authors examined the effect of certified personal trainer services on exercise behavior by using the transtheoretical model of behavioral change. PARTICIPANTS: Female college students (n = 449) completed surveys during the first week (T1) and last week (T2) of the fall semester. METHODS: Students receiving personal trainer services during the fall semester (experimental group, n = 31) were cross-matched with students who had not received services (control group, n = 31). RESULTS: The control group demonstrated a statistically significant regression in stage of exercise change scores; the experimental group did not. The authors found the 2 groups to have a statistically significant difference in the pattern of exercise behavior change over the course of the semester, with more active maintainers and progressors in the experimental group. CONCLUSIONS: Cognitive and behavioral processes of change, decisional balance, and scheduling self-efficacy significantly decreased in the control group, whereas cognitive processes of change, decisional balance, and scheduling self-efficacy remained statistically unchanged in the experimental group.     

Non-estrogen-based treatments for menopausal symptoms

The British Menopause Society Council is committed to provide up-to-date authoritative reviews to aid health professionals to inform and advise women about key issues in postreproductive health. This guidance refers to non-estrogen-based treatments for menopausal symptoms, such as hot flushes, symptoms of urogenital atrophy and lack of sexual desire. Treatment of choice should be based on up to-date information and targeted to individual women's needs. Non-hormonal strategies may be useful for women with estrogen-dependent disease such as breast cancer.     

Stepfamily childbearing in Sweden: quantum and tempo effects, 1950-99

Several studies have demonstrated that stepfamily couples have a higher risk of childbearing than couples in a stable union with the same total number of children. Analysing retrospective data from a nationally representative sample of Swedish adults, we find that the risk of a second or third birth is higher when it is the first or second child in a new union. We also find a faster pace of childbearing after stepfamily formation than after a shared birth. The risk of a second birth (in total) is only a little higher in the first two years after stepfamily formation than in the first two years after a shared birth, and thereafter the risk is lower for stepfamilies. The risk of a third birth (in total) is particularly high early in the stepfamily union and remains higher than that of couples with two shared children for at least five years. The stepfamily difference was lower after than before 1980, when the Swedish government introduced parental leave incentives for short birth intervals.     

A comparison of estimators for regression models with change points

We consider two problems concerning locating change points in a linear regression model. One involves jump discontinuities (change-point) in a regression model and the other involves regression lines connected at unknown points. We compare four methods for estimating single or multiple change points in a regression model, when both the error variance and regression coefficients change simultaneously at the unknown point(s): Bayesian, Julious, grid search, and the segmented methods. The proposed methods are evaluated via a simulation study and compared via some standard measures of estimation bias and precision. Finally, the methods are illustrated and compared using three real data sets. The simulation and empirical results overall favor both the segmented and Bayesian methods of estimation, which simultaneously estimate the change point and the other model parameters, though only the Bayesian method is able to handle both continuous and dis-continuous change point problems successfully. If it is known that regression lines are continuous then the segmented method ranked first among methods.     

The Impact of Devolution on Nonprofits

The following article reviews the results of a multiphase study of nonprofit social service organizations serving children and youth in Cuyahoga County, Ohio. The purpose of the study was to assess the impact of devolution and related efforts to introduce the new public management in the nonprofit sector. Study results strongly suggest that the capacity of community-based and faith-based organizations to adopt the business-oriented approach required to meet the expectations of government contracts is profoundly limited by their financial and human resources and by the conflict that a market orientation can present to the nonprofit mission.