A rank test for constancy of a location oil scale parameter

X nonlinear rank statistic is proposed to test whether a location or scale parameter of a continuous distribution has remained constant over time. The test is based on frequency domain characteristics of the data and uses the periodogram of appropriate rank scores. The test has good power against alternatives involving multiple abrupt up and down changes     

Substance abuse, suicidality, and self-esteem in South African adolescents

Associations among six different domains of self-esteem (peers, school, family, sports/athletics, body image, and global self-worth) and risk behaviors related to substance use and suicidality were investigated in a sample of South African adolescents. Students enrolled in Grades 8 and 11 at independent secondary schools in Cape Town (N = 116) completed the Self-Esteem Questionnaire (SEQ) and a questionnaire that asked about their participation in a range of risk behaviors. Logistic regression analyses indicated that particular domains of self-esteem were differentially associated with indicators of alcohol, cigarette and drug use and suicidal ideation or behaviors in adolescents. Family self-esteem showed the strongest overall pattern of associations with the risk behaviors. Overall, the findings of this study suggest that interventions which aim to protect adolescents from engaging in risk behaviors by increasing their self-esteem are likely to be most effective and cost-efficient if they are aimed at the family and school domains.     

The Association Between Gay Men's Stereotypic Beliefs About Drag Queens and Their Endorsement of Hypermasculinity

To date, few researchers have investigated gay men's stereotypic beliefs about drag queens and the association between these beliefs and individual difference variables such as hypermasculinity. To address this omission, 118 men self-identifying as non-heterosexual completed an online survey consisting of an adjective checklist about drag queens and a psychometrically sound indicant of hypermasculinity. As predicted, participants who were more likely to endorse hypermasculine belief statements tended to perceive negatively valenced attributes as more characteristic of drag queens. Possible explanations for this relationship, limitations associated with the current study, and directions for future research are delineated.     

WOMEN'S RISING MARKET OPPORTUNITIES AND INCREASED LABOR FORCE PARTICIPATION

This paper examines the secular increase in the labor market activity of married women in the United States from 1975 to 1991. The research stresses two findings consistent with the hypothesis that married women increased their attachment to the labor force during this time period. First, increasing duration, not incidence, of married women's employment spells contributes the most to the increase in their rate of employment from 1975 to 1991. Second, the increase in married women's employment over the 1980s is largely due to their increased willingness to work more at any given wage, not their rising wage opportunities. ( JEL J22, J31, J64)     

The impact of social transformation on the non-government welfare sector and the social work profession

This article examines changes to non-government social welfare, their impact on service delivery and on the social work profession. To redress the legacy of the past and the consequent inequalities in social welfare, in the first decade of democracy the government allocated the bulk of its welfare resources to transforming the social security system at the expense of social service delivery. As a result, South Africa has a costly social security budget with social services on the brink of collapse, leaving social workers and other social service professionals with low morale in the face of the huge challenge of providing welfare services with scarce resources, especially in the non-government sector. Nevertheless, social work remains an important role player in social development. From its marginalised position in the first decade of democracy, in the second decade it is repositioning itself as a recognised contributor to reconstruction and development in South Africa.     

Asymptotic distributions of quadratic forms occurring in changepoint problems

A stochastic-process approach is used to derive the asymptotic distributions of quadratic forms occurring in the analysis of changepoint data.     

A multivariate rank test for comparing mass size distributions

Particle size analyses of a raw material are commonplace in the mineral processing industry. Knowledge of particle size distributions is crucial in planning milling operations to enable an optimum degree of liberation of valuable mineral phases, to minimize plant losses due to an excess of oversize or undersize material or to attain a size distribution that fits a contractual specification. The problem addressed in the present paper is how to test the equality of two or more underlying size distributions. A distinguishing feature of these size distributions is that they are not based on counts of individual particles. Rather, they are mass size distributions giving the fractions of the total mass of a sampled material lying in each of a number of size intervals. As such, the data are compositional in nature, using the terminology of Aitchison [1 Aitchison, J. 1986. “The Statistical Analysis of Compositional Data”. London: Chapman and Hall. [Crossref] , [Google Scholar]] that is, multivariate vectors the components of which add to 100%. In the literature, various versions of Hotelling's T ² have been used to compare matched pairs of such compositional data. In this paper, we propose a robust test procedure based on ranks as a competitor to Hotelling's T ². In contrast to the latter statistic, the power of the rank test is not unduly affected by the presence of outliers or of zeros among the data.     

Horizontal plane sound source localization and auditory enhancement

Accurate sound source localization has advantages for the performance of work by humans. The ability to accurately localize sound sources contributes to perception, decision making and task performance. Two studies were conducted to investigate the prevalence of accurate sound source localization and the enhancement that spatially separated sound source locations can have on speech perception. The first study was conducted to characterize the ability to detect the location of horizontal plane sound sources. A sample of 117 participants with the hearing capacity within the normal limits participated in the study. The results indicated that sound sources located towards the front of the participant were identified more frequently than those sound sources located towards the rear positions. Based on the results found in the first study, a second study was conducted to assess performance within a listening task. Three different spatial configurations were used to assess if similar trends in performance translated to sound sources through headphones. Fifteen research participants performed a Coordinated Response Measure (CRM) task requiring the identification of a speech phrase and its associated information for a diotic configuration and two different spatial sound source configurations. Performance measured for the diotic configuration was significantly (p(0.05) less than for the two spatial configurations. The current studies indicate distinct advantages of utilizing localized sound sources to present auditory signal and speech to listeners.