Parameter estimation of Lindley step stress model with independent competing risk under type 1 censoring

Abstract

In literature, Lindley distribution is considered as an alternative to exponential distribution to fit lifetime data. In the present work, a Lindley step-stress model with independent causes of failure is proposed. An algorithm to generate random samples from the proposed model under type 1 censoring scheme is developed. Point and interval estimation of the model parameters is carried out using maximum likelihood method and percentile bootstrap approach. To understand the effectiveness of the resulting estimates, numerical illustration is provided based on simulated and real-life data sets.     

Finie mixures of canonical fundamenal skew $$$$-disribuions

This paper introduces a finite mixture of canonical fundamental skew \(t\) (CFUST) distributions for a model-based approach to clustering where the clusters are asymmetric and possibly long-tailed (in: Lee and McLachlan, arXiv:1401.8182 [statME], 2014b). The family of CFUST distributions includes the restricted multivariate skew \(t\) and unrestricted multivariate skew \(t\) distributions as special cases. In recent years, a few versions of the multivariate skew \(t\) (MST) mixture model have been put forward, together with various EM-type algorithms for parameter estimation. These formulations adopted either a restricted or unrestricted characterization for their MST densities. In this paper, we examine a natural generalization of these developments, employing the CFUST distribution as the parametric family for the component distributions, and point out that the restricted and unrestricted characterizations can be unified under this general formulation. We show that an exact implementation of the EM algorithm can be achieved for the CFUST distribution and mixtures of this distribution, and present some new analytical results for a conditional expectation involved in the E-step.     

Trustworthiness in evaluation practice: an emphasis on the relational

As canons for trustworthiness developed explicitly in the discourse of qualitative inquiry, the emphasis was on procedural matters rather than fundamentally relational ones. A nod was made to the relational in such strategies as “member checks” but the issues of how the evaluator actually relates to participants and to the larger communities of practice and discourse—matters subsumed under moral principles and ethical standards—were often marginalized. This chapter posits that the first consideration in designing and conducting rigorous evaluation inquiry, and in critiquing the results of any research, should be the study's trustworthiness. Judging a study's trustworthiness, however, should focus on much more than procedural matters; it should also rely on moral principles and ethical standards which specifically address how we relate to an evaluation's participants. Central to these considerations are cross-cultural sensibilities about the nuanced meanings associated with any principles and standards. The chapter provides a theoretical framework for this position and offers two illustrative examples in the form of dialogues.     

Characteristics of the female athlete triad in collegiate cross-country runners

The Female Athlete Triad is a life-threatening syndrome defined by disordered eating, amenorrhea, and osteoporosis. OBJECTIVE AND PARTICIPANTS: The author's purpose in this study was to examine female cross-country runners' (N=300) calcium consumption, along with the prevalence of 2 components of the triad: disordered eating and menstrual dysfunction. METHODS: The author used measures including the Orientation to Exercise Questionnaire, Calcium Rapid Assessment Method, and questions related to height, weight, exercise time, perceptions of eating disorders, and menstrual status. Previous or current eating disorders were reported by 19.4% of the women, 23.0% had irregular menstrual cycles, and 29.1% had inadequate calcium intake. RESULTS: Those athletes perceiving a previous/current eating disorder scored higher on the Orientation to Exercise questionnaire than did those who did not perceive such. CONCLUSION: The author recommends educational efforts for the prevention of components of the Female Athlete Triad.     

Pearls and pitfalls in evaluating a Student Assistance Program: a five-year case study

This article presents data from a five-year evaluation-research case study of a large urban schools district's internal Student Assistance Program (SAP). The district employed specially trained and licensed school-based counselors to implement an internal SAP expanded to include tertiary prevention, and modeled after an employee assistance program established for adults. From the population of more than 10,000 students who received some type of program assistance for at-risk behaviors, a stratified random sample of 2,238 cases, over a five year period, were reviewed. Results indicate a statistically significant decline (p < .05) in students' drug use and a significant improvement in internal locus of control occurred each year. While not statistically significant, the average number of student discipline referrals was less than the year prior to program admission; however, there was no significant change in academic performance. A significant correlation between students' drug use and the amount of time in program, the type of assistance received, and the student's custody status was also found.     

Religious Social Identities in the Hybrid Self‐presentations of Sikh Businesspeople

This paper explores the identity work practices of Thai Sikh businesspeople. The paper focuses on two important social identities in participants’ self‐presentations – those derived from religious (Sikh) and western business discourses – and identifies powerful tensions in their hybrid identity work. Conducting discourse analysis on identity work practices within interview settings, the authors explore how participants resolve, accommodate or reject these discursive tensions while attempting stable and coherent hybrid self‐presentations. They identify several different forms of hybridity, including what they term ‘equipollence’, which occurs when two equally powerful, contradictory discourses are incorporated in self‐presentations, producing potentially irresolvable intersections and leading to a lack of coherence. Contributions are made to the literatures on religion and work, hybrid identity work processes and social identities.     

Women and border policing at the edges of Europe

While states around the world have responded to mass mobility by increasing border policing, our knowledge of the daily reality of that form of policing remains limited. How migrant women are policed has been particularly neglected. The political and practical difficulty of examining the context, process and experience of border control practices appears often to be insurmountable. This article contributes to filling some of the gaps in our knowledge by drawing on ethnographic data collected over a 12-month period in Greek immigration detention centres from 2011 to 2012. In it we examine the experience of policing and irregular entry across the Greek Turkey border – an entry-point to Europe that is routinely regarded as being in crisis. As we will demonstrate, border policing at this site is capricious and unpredictable. It is also highly racialised and gendered.     

“Everything That We Can Do”: A Content Analysis of the Protective Strategies Used by GLBTQ Parents

Despite increased access to parenting rights through legal marriage and adoption, U.S. gay, lesbian, bisexual, transgender, and queer (GLBTQ) parents continue to experience varying levels of support for their families. This study explored protective strategies, or actions taken to meet one's safety needs when vulnerable, that GLBTQ parents pursue. This study included 454 GLBTQ parents from a national survey. Participants' open-ended responses about protective strategies were extracted from the survey and analyzed using content analysis. Responses were coded into 10 categories capturing strategies GLBTQ parents used to protect their families. While strategies utilizing legal supports were common, the most cited strategies were symbolic strategies, including creating a family name and developing written statements of parent wishes. Exploratory analyses revealed no difference in mean number of strategies used between parents who reported having legal status as a parent through adoption or listing on the birth certificate and those without legal parenting status. These results suggest that GLBTQ parents, regardless of their legal parenting status, take intentional measures to achieve a sense of safety and increase social support. The findings reiterate the importance of both legal and social support of GLBTQ parents.     

Variations in the Life Histories of Incarcerated Parents by Race and Ethnicity: Implications for Service Provision

ABSTRACT

Incarcerated parents have complex life histories that often remain unresolved during incarceration, can continue to create barriers to prosocial success on release, and present similar intergenerational challenges for their children. This study examines the life histories of incarcerated fathers and mothers from the Pacific Northwest and how their experiences vary based on race and ethnicity. Five areas examined were exposure to trauma, child welfare involvement, mental health and substance abuse problems, juvenile justice and adult criminal justice involvement, and intergenerational criminal justice involvement. The sample comprised 359 incarcerated parents, and their racial/ethnic composition was 59% White, 14% African American, 11% multiracial, 8% Native American, and 7% Latino. Few differences were found across racial and ethnic groups. Mothers appeared more similar to each other across groups than fathers. Results illustrated similarities yet some surprising differences with national trends on key study variables. Implications for future research and intervention and prevention are discussed.