Competing risks,left truncation and late entry effect in A-bomb survivors cohort

The cohort under study comprises A-bomb survivors residing in Hiroshima Prefecture since 1968. After this year, thousands of survivors were newly recognized every year. The aim of this study is to determine whether the survival experience of the late entrants to the cohort is significantly different from the registered population in 1968. Parametric models that account for left truncation and competing risks were developed by using sub-hazard functions. A Weibull distribution was used to determine the possible existence of a late entry effect in Hiroshima A-bomb survivors. The competing risks framework shows that there might be a late entry effect in the male and female groups. Our findings are congruent with previous studies analysing similar populations.     

On the comparison of the Fisher information of the log-normal and generalized Rayleigh distributions

Surles and Padgett recently considered two-parameter Burr Type X distribution by introducing a scale parameter and called it the generalized Rayleigh distribution. It is observed that the generalized Rayleigh and log-normal distributions have many common properties and both distributions can be used quite effectively to analyze skewed data set. In this paper, we mainly compare the Fisher information matrices of the two distributions for complete and censored observations. Although, both distributions may provide similar data fit and are quite similar in nature in many aspects, the corresponding Fisher information matrices can be quite different. We compute the total information measures of the two distributions for different parameter ranges and also compare the loss of information due to censoring. Real data analysis has been performed for illustrative purposes.     

Enhancing the capacity of kin caregivers and their families to meet the needs of children left behind

Based on qualitative research of the experiences of 23 kin caregivers and five school personnel, this article explores the role of informal kinship care in addressing the needs of school-age children left behind in rural China. The findings of this study suggest that kin caregivers' child-rearing capacity is limited in the rural context, and they are often overwhelmed by children's diverse and complex needs, particularly their emotional ones. In view of the huge population and their vulnerability, it is imperative for the state to take up its responsibilities and develop specific social work services and other support for children left behind and their families.     

社会转型与农村留守妇女角色地位的转变

城市化造成大量农村男性劳动力外出务工,加上城乡"二元结构"所形成的城乡分割状况,由此形成了农村"留守妇女"这一新的群体。她们在政治生活、农业生产、社会生活和家庭生活中的角色地位从以前次要地位转变成现在的主要地位。角色地位的转变给留守妇女带来了生活、精神的巨大压力。针对留守妇女存在诸如角色转变所带来的新问题,应该加大对留守妇女生活的帮助和扶持,加强农村社区安全建设,排遣其生活压力,丰富其文化生活,提高其致富能力。     

风险社会理论视角下农村留守儿童的困境

我国目前正处于社会转型期,伴随着社会转型的不断深化,在农村出现了大量的留守儿童。从风险社会理论的角度看,他们面临健康风险、心理风险、安全风险与学习风险。这个问题的解决有赖于家庭、学校、社会、政府等各方面的共同努力和合作。     

最简方案下英汉存现句的句法研究

存现句在英语和汉语中普遍存在,且有同有异,但有关英汉存现结构的现有解释机制仍有不足。文章以乔姆斯基（1998,1999）最简探索理论为背景,在Collins（2005）提出的左向移动假说的理论框架下从句法层面对英汉存现句作了统一的解释。     

极左思潮对中国社会主义现代化建设的影响

现代化进程本质上就是马克思主义进一步中国化的过程,只有坚持把马克思主义普遍原理与现代化建设的具体实际相结合,而且要结合好,才能完成这一艰巨任务,否则就会导致理论和实践上的迷误.极左思潮的产生、形成和发展,其根源正是由于我们党在探索社会主义现代化建设道路之初,没有解决好马克思主义中国化的问题,没有把马克思主义普遍原理与社会主义现代化建设的具体实际结合好,使其对现代化建设产生了很大的干扰,甚至破坏.     

论蒙古族的拇指崇拜

拇指崇拜是蒙古族独特的文化现象 ,古代蒙古人神化了在狩猎过程中弓箭手的拇指作用 ,因而产生了拇指崇拜。蒙古族认为拇指是男子汉的象征、英雄人物的化身。同时 ,拇指崇拜与蒙古族尊右习俗有着密切的关系。     

On the incidence–prevalence relation and length‐biased sampling

For many diseases, logistic constraints render large incidence studies difficult to carry out. This becomes a drawback, particularly when a new study is needed each time the incidence rate is investigated in a new population. By carrying out a prevalent cohort study with follow‐up it is possible to estimate the incidence rate if it is constant. The authors derive the maximum likelihood estimator (MLE) of the overall incidence rate, λ, as well as age‐specific incidence rates, by exploiting the epidemiologic relationship, (prevalence odds) = (incidence rate) × (mean duration) (P/[1 ? P] = λ × µ). The authors establish the asymptotic distributions of the MLEs and provide approximate confidence intervals for the parameters. Moreover, the MLE of λ is asymptotically most efficient and is the natural estimator obtained by substituting the marginal maximum likelihood estimators for P and µ into P/[1 ? P] = λ × µ. Following‐up the subjects allows the authors to develop these widely applicable procedures. The authors apply their methods to data collected as part of the Canadian Study of Health and Ageing to estimate the incidence rate of dementia amongst elderly Canadians. The Canadian Journal of Statistics © 2009 Statistical Society of Canada     

Left truncation in linked data: A practical guide to understanding left truncation and applying it using SAS and R

Time-to-event data such as time to death are broadly used in medical research and drug development to understand the efficacy of a therapeutic. For time-to-event data, right censoring (data only observed up to a certain point of time) is common and easy to recognize. Methods that use right censored data, such as the Kaplan–Meier estimator and the Cox proportional hazard model, are well established. Time-to-event data can also be left truncated, which arises when patients are excluded from the sample because their events occur before a specific milestone, potentially resulting in an immortal time bias. For example, in a study evaluating the association between biomarker status and overall survival, patients who did not live long enough to receive a genomic test were not observed in the study. Left truncation causes selection bias and often leads to an overestimate of survival time. In this tutorial, we used a nationwide electronic health record-derived de-identified database to demonstrate how to analyze left truncated and right censored data without bias using example code from SAS and R.