A Semiparametric Approach for Accelerated Failure Time Models with Covariates Subject to Measurement Error

There are relatively few discussions about measurement error in the accelerated failure time (AFT) model, particularly for the semiparametric AFT model. In this article, we propose an adjusted estimation procedure for the semiparametric AFT model with covariates subject to measurement error, based on the profile likelihood approach and simulation and exploration (SIMEX) method. The simulation studies show that the proposed semiparametric SIMEX approach performs well. The proposed approach is applied to a coronary heart disease dataset from the Busselton Health study for illustration.     

Assessing participants’ perceptions on group-based principles for action in community-based health enhancing physical activity programmes: The APEF tool

In community-based health enhancing physical activity (CBHEPA) programmes, group-based principles for action such as active participation, enjoyment, and fostering group processes are widely advocated. However, not much is known about participants’ perceptions of these principles as there are no assessment tools available. Therefore, this article describes the development of the APEF (Active Participation, Enjoyment, and Fostering group processes) tool and reports on its implementation in a Dutch CBHEPA programme. Indicators for the principles have been identified from literature research, interviews with professionals, and secondary analysis of three group interviews with 11 practitioners. To address the identified indicators, the APEF tool was developed, pretested, and used in 10 focus groups with 76 participants.The APEF tool consists of eight statements about group-based principles for action, on which CBHEPA participants vote, followed by in-depth discussion. The voting procedure engages participants. Spider diagrams visualise participants’ perceptions of group-based principles.The APEF tool addresses the challenge of relating group level outcomes to individual outcomes such as physical activity behaviour. The tool facilitates as well as evaluates group-based principles for action, it stimulates dialogue and is culturally sensitive, but it needs strong facilitating skills to manage group dynamics.     

Efficient Estimation of Parameters of the Negative Binomial Distribution

In this article we investigate a class of moment-based estimators, called power method estimators, which can be almost as efficient as maximum likelihood estimators and achieve a lower asymptotic variance than the standard zero term method and method of moments estimators. We investigate different methods of implementing the power method in practice and examine the robustness and efficiency of the power method estimators.     

Two Pitfalls of Using Standard Regression Diagnostics When Both X and Y Have Measurement Error

Modern exploratory data analysis produces models that are not based on physical theory but that are consistent with pictures of the data. When both X and Y have error this can be risky, because important features are hidden. Two examples are given that show that systematic model departures and heteroscedasticity may not be detectable with standard regression diagnostics.     

社会工作研究的人文精神——对以实证主义为导向的美国社会工作研究的批判

长期以来,国际社会工作研究常常倾向于以实证主义和经验主义为基础的研究导向,特别是在美国,基于证据的研究方法在社会工作领域十分流行。随着全球化的推进和人们生活方式的现代化,社会工作研究所面临的问题更为复杂,其解决方法单纯依靠各种技术处理的手段来展开是远远不够的,我们在讨论这些问题时,要强化其价值导向。这要求我们在讨论社会工作研究的问题上,把我们的关注点从证据、技术手段和职业标准扩展到价值观、人文精神和对全球化问题的关注等方面,以此来推进国际社会工作的发展。     

The Method to Identify a Biomarker and to Evaluate Its Efficiency for Survival by Using the Joint Model of the Accelerate Failure Time and Longitudinal Data

In this article, we discuss how to identify longitudinal biomarkers in survival analysis under the accelerated failure time model and also discuss the effectiveness of biomarkers under the accelerated failure time model. Two methods proposed by Shcemper et al. are deployed to measure the efficacy of biomarkers. We use simulations to explore how the factors can influence the power of a score test to detect the association of a longitudinal biomarker and the survival time. These factors include the functional form of the random effects from the longitudinal biomarkers, in the different number of individuals, and time points per individual. The simulations are used to explore how the number of individuals, the number of time points per individual influence the effectiveness of the biomarker to predict survival at the given endpoint under the accelerated failure time model. We illustrate our methods using a prothrombin index as a predictor of survival in liver cirrhosis patients.     

Bivariate short distributions

The method of MML estimation for a univariate normal (Tiku 1967, 1973) is extended to a bivariate normal population. Thus, a theoretical foundation is given to the robust correlation coefficient proposed by Tiku and Balakrishnan (1986).     

分支蚁群动态扰动算法求解TSP问题

蚁群优化算法是一种求解组合优化难题的强启发式算法,它利用正反馈和并行计算原理,具备很强的搜索能力。近年来,蚁群优化算法广泛应用于TSP问题的研究。本文提出分支蚁群动态扰动(DPBAC)算法,该算法主要从5个方面对基本蚁群算法做出改进:引入分支策略选取出发城市;改进状态转移规则;引入变异策略改进蚂蚁路径;改进信息素更新规则;引入条件动态扰动策略。实验表明,该算法可以有效改善基本蚁群算法搜索时间较长、容易陷入局部极小等缺点。     

土木工程专业《混凝土结构》课程教学方法和内容探讨

文章从土木工程专业的《混凝土结构》课程着手,探讨了适应新变革需求的教学内容和方法,提出了自己的认识,以期得到广泛的重视和认同,从而保证相关教学工作能顺利进行。     

企业营销道德水准测试的指标体系及评价方法研究

本文是“企业营销道德水准测试及评价系统”课题的前期研究成果。作者首先通过探测性调研确定了影响营销道德水准评价的企业营销行为,并在定量调研基础上将其归并为七个评价营销道德水准的维度,同样还根据定量调研的结果确定了企业营销道德水准的测评方法,为营销道德水准测试与评价系统的建立构筑了重要基础。