The competing risks analysis for parallel and series systems using Type-II progressive censoring

Abstract

Recently, the study of the lifetime of systems in reliability and survival analysis in the presence of several causes of failure (competing risks) has attracted attention in the literature. In this paper, series and parallel systems with exponential lifetime for each item of the system are considered. Several causes of failure independently affect lifetime distributions and observations of failure times of the systems are considered under progressive Type-II censored scheme. For series systems, the maximum likelihood estimates of parameters are computed and confidence intervals for parameters of the model are obtained using Fisher information matrix. For parallel systems, the generalized EM algorithm which uses the Newton-Raphson algorithm inside the EM algorithm is used to compute the maximum likelihood estimates of parameters. Also, the standard errors of the maximum likelihood estimates are computed by using the supplemented EM algorithm. The simulation study confirms the good performance of the introduced approach.     

HR systems and leadership attachment affecting idea generation and implementation: An experiment and two-source multi-level study

This paper focuses on the direct and interactive influence of leadership attachment styles (secure, anxious, and avoidant) and commitment HR system on two distinct stages of the individual innovation process—idea generation and implementation. We test our hypotheses in two studies. An experimental study of undergraduate students establishes a positive effect of secure attachment on idea implementation. The interplay between commitment HR system and avoidant attachment marginally predict idea generation; commitment HR system and neither secure nor anxious attachment predict implementation. A multisource multi-level field study in three EU-based private firms replicates the direct role of commitment HR system in stimulating idea implementation (but not generation) and suggests that secure attachment fosters both generation and implementation, whereas anxious attachment hinders both. Moderation analyses support only a marginal interaction between commitment HR system and secure attachment in fostering idea generation. We discuss theoretical, practical, and future research implications.     

The racialized patterns of police violence: The critical importance of research as praxis

The tragic killing of George Floyd at the hands of the police resulted in hundreds of thousands of protestors marching in the streets demanding change. The call for change criticized the killing of Blacks by law enforcement and challenged White supremacy as an institution of social control and racial violence. A key component of the marches and protests was a message to the residents of the United States: “Black Lives Matter.” As society grapples with a reckoning, researchers studying police violence for the past 6 decades have been empirically and theoretically debating the reasons why use of force by law enforcement continues to have a higher proportion of Black and Brown victims compared to Whites. Although the research on fatal police killings was studied by only a small number of individuals prior to 2014, after the killing of Michael Brown in Ferguson, Missouri the research in different areas of the country increased rapidly as did the forms of analysis and research disciplines making their own contributions. The Washington Post and Guardian news agencies established that deaths at the hands of the police were occurring for at least 900 to 1100 individual deaths per year for which firearms resulted in the greatest cause of death. As US government agencies failed to produce a national data source on police involved killings, the media took a leading role in providing greater national understanding. The authors examine what role academic researchers contribute to the discussion for solutions, particularly those from marginalized backgrounds. As protestors march, lawyers sue and defend, and politicians create new forms of legislation, researchers need to play a more important role initiating critical studies, making sense of the data, and providing a theoretical framework for which police violence can be understood. This article will provide an overview of the literature on racialized police violence, point out key patterns involving racial and ethnic disparities, and emphasize how researchers can play a more important role in advocating for change.     

Using small data to interpret big data: 311 reports as individual contributions to informal social control in urban neighborhoods

Informal social control is considered a vital component of the well-being of urban communities. Though some argue that the actions that constitute this social process are often said to reflect territoriality, little else is known about how individuals contribute to it. The current study leverages a database of over 600,000 requests for government services received by the city of Boston, MA's 311 system as a way to answer such questions, focusing particularly on reports of issues in the public space arising from incivilities. In order to establish construct validity for the “big data” of the 311 system, they are combined with the “small data” of a survey of 311 users, permitting the simultaneous analysis of objective reporting behaviors with self-report attitudes. The analysis occurs in two parts. First, reporting of incivilities is distinguished behaviorally from reporting public issues arising from natural deterioration, and people are found to specialize in one or the other. Second, the survey is used to test whether the reports are a reflection of territoriality. Reports of incivilities were unique in their association with a desire to enforce local social norms. They were also associated with a second territorial motivation to benefit the community. Implications for future research are discussed.     

When the Norwegian child-welfare services get involved: parents making sense of referrals

There is limited research exploring parents' views and understanding of referrals to the child-welfare services (CWS). This study explores parents' understanding of the circumstances leading to a child-welfare referral, and their understanding of the reporter's objectives in making the referral. Qualitative content analysis and frequency analysis was performed on open-ended survey responses from a sample of 683 Norwegian parents in contact with the CWS. The results showed that the majority (60.2%) of the parents perceived the referral to be initiated solely because of parental difficulties and multiple family life stressors. Some of the parents (22.8%) believed the referrals were initiated exclusively because of their children's problems, whereas a few (13.3%) perceived it to be a combination of parental/familial difficulties and children's problems. The findings reveal that close to half of the parents (46.4%) felt the objective of the person making the referral was to help the child, their parents and the family. Some (36.5%) saw it as a routine or mandated action by public or official services, while others (18.7%) reported that they did not know why referrals had been made, or gave no answer to the question. A small group of parents (6%) viewed the referral as an act of harassment. The main implications of these findings are discussed.     

Extremum sieve estimation in k-out-of-n systems

This article considers the non parametric estimation of absolutely continuous distribution functions of independent lifetimes of non identical components in k-out-of-n systems, 2 ? k ? n, from the observed “autopsy” data. In economics, ascending “button” or “clock” auctions with n heterogeneous bidders with independent private values present 2-out-of-n systems. Classical competing risks models are examples of n-out-of-n systems. Under weak conditions on the underlying distributions, the estimation problem is shown to be well-posed and the suggested extremum sieve estimator is proven to be consistent. This article considers the sieve spaces of Bernstein polynomials which allow to easily implement constraints on the monotonicity of estimated distribution functions.     

文学视野下的古栈道文化遗存

连云栈道是古代通行汉中和巴蜀的重要栈道之一,素以恢宏险峻而名驰天下。作为古代的交通要津,它承载着极为厚重的历史文化信息,记录着王朝兴废的更迭嬗变,演绎出一幕幕惊心动魄、可歌可泣的历史活剧,雄杰之士为之折腰,骚人墨客赋咏不绝。或直笔正描,赞叹栈道的奇伟险绝;或托物兴感,展示坎坷不遇的失意情怀;或触景生情,抒发古今变异、世事沧桑、兴亡倏忽的人生感触;或侧写旁点,表现伤时念乱的时代忧患意识,显示出多元的艺术视野。     

Healthy Barbs: Activism Confronts Mortality

Barbara Brenner, JD, was the Executive Director of Breast Cancer Action (BCA) from 1995–2010. Before that, she was a longtime activist in the anti-war movement and an attorney who, for most of her career, practiced public policy law. After she was diagnosed with breast cancer in 1993 at the age of 41, she took the helm of BCA. Under her leadership, the organization moved into a position of national advocacy—demanding research on the causes and prevention of breast cancer, including the role of industrial pollutants. Barbara started the “Think Before You Pink” campaign, encouraging people to question whether companies that display pink ribbons actually produce products that harm women's health or generate any funds to fight breast cancer. Her blog, “Healthy Barbs,” challenged readers to critique routine healthcare practices and policies. Barbara received numerous awards, including a Jefferson Award for Public Service in 2007, the Smith College Medal in 2012, and the ACLU-Northern California's Lola Hanzel Courageous Advocacy Award in 2012. Barbara had a recurrence of breast cancer in 1996. She died of complications associated with amyotrophic lateral sclerosis, ALS, on May 10, 2013.     

库切与凯里写作视角比较研究

在布克文学奖的颁奖史上，只有两位作家两度获奖，他们是彼得·凯里（PeterCarey）和J．M．库切（J．M．Coetzee），且这两位作家目前都拥有澳大利亚国籍。当文学研究者将这两位作家纳入文学研究范畴进行分析时，发现可以从世界文学与比较文学的角度研究这两位作家的作品。本文将从第三种文化的角度分析两住作家的作品，特别是他们在流散过程中所创作的具体作品来梳理他们的写作策略。     

Stochastic comparisons between extreme order statistics from scale models

Stochastic ordering relations between extreme order statistics from exponential, Weibull and gamma distributions have been studied extensively by many researchers in recent years. In this work, we obtain various ordering results for the comparisons of two extreme order statistics from scale models when one set of scale parameters majorizes the other. The new results obtained here are applied when the baseline distributions are exponentiated Weibull or generalized gamma distributions. In this way, we generalize and extend some results established recently in the literature.