Inconsistency of the MLE for the Joint Distribution of Interval-Censored Survival Times and Continuous Marks

Abstract.  This paper considers the non-parametric maximum likelihood estimator (MLE) for the joint distribution function of an interval-censored survival time and a continuous mark variable. We provide a new explicit formula for the MLE in this problem. We use this formula and the mark-specific cumulative hazard function of Huang & Louis (1998) to obtain the almost sure limit of the MLE. This result leads to necessary and sufficient conditions for consistency of the MLE, which imply that the MLE is inconsistent in general. We show that the inconsistency can be repaired by discretizing the marks. Our theoretical results are supported by simulations.     

基于社会学习理论的在线评论信息对购买决策的影响研究

消费者在线商品评论对电商企业提高销售业绩,消费者制定购买决策等都有重要作用。本文基于社会学习理论,运用贝叶斯和高斯更新公式构建社会学习模型,分析消费者通过社会学习评论数量和等级对其购买决策的差异性影响,并深入探析评论数量和等级的内在关系,运用数值试验和电子商务网站获取的真实数据,验证了模型和结论的有效性。结果表明评论等级与评论数量存在负相关关系,评论等级随销售量和评论数量增加而下降; 但当评论数量达到某值后,评论等级受评论数量影响不大,评论等级对销售量有积极作用,评论数量对高质量产品销售量有积极作用,对低质量产品销售量没有积极影响。本文结果说明评论数量和等级在不同销售期对不同产品的购买决策有差异性影响,从而有利于电商企业在不同销售期制定相应的营销策略。     

人的心理冲突与矛盾产生根源剖析

社会变革是人的心理冲突和矛盾产生的根本原因。社会文化震荡是人的心理矛盾和冲突产生的文化根源;社会各阶层地位的不均衡是人的心理冲突和矛盾产生的深层社会根源;人际关系的变化是人的心理冲突和矛盾产生的直接原因;社会分配方式和生活方式的变化是人的心理矛盾和冲突产生的重要原因。     

基于区间数的多阶段交互式群体评价方法及应用

针对目前多阶段交互式评价研究数量相对较少并且均是基于点值评价信息的缺陷,以及大多数群体评价研究中忽视了评分区间与可变评价信息的内在联系等不足,综合讨论了一种基于区间数的多阶段交互式群体评价方法。本文首先分析了交互式评价中区间型评价信息的特性,进而提出了评分区间重置算法的设计思想。该算法能够实现评分区间与每轮调整后评价信息的协同调整,并推动交互的进行,使评价信息趋于稳定。然后从稳定性角度出发,设计群体评价信息的稳定性指标,以此讨论交互终止条件。最后给出一个应用算例,算例表明了该方法的可行性和有效性。     

论电视新闻的变革对中国政治改革的启示——以《新闻联播》为例

为挽救“收视率”危机,《新闻联播》在人才选拔、尊重规律与评估体系三方面进行了深刻的变革。同时,中国政府近年来也面临着“信任度”降低的困境,为此政府进行了多次政治改革。由于政府提升“信任度”与《新闻联播》提高“收视率”存在着目标的一致性,因此,从组织行为学的视角,采用比较的研究方法,对政府所进行的政治改革与《新闻联播》的变革之间的关系进行了细致剖析,认为《新闻联播》在提高收视率的渐进过程中所采取的变革措施可以为中国政府提高“信任度”而进行的政治改革提供理论与实践的依据。     

论以学生为主体的高等学校教学质量评价

高等学校实施的以学生为主体的教学质量评价指学生按照规定的项目和程序给任课教师打分或分等。这种评价方式基于教育学和心理学的合理假设,具有相当信度,但也存在一些有待解决的问题,如评价指标和项目的设计、评价集的选择、参评学生样本、对教师的教学发展潜力考察以及某些社会风气对学生价值观的影响等等,应采取相应措施加以解决。     

Deterministic Evolution of Strength in Multiple Comparisons Models: Who is the Greatest Golfer?

We present a statistical methodology for fitting time‐varying rankings, by estimating the strength parameters of the Plackett–Luce multiple comparisons model at regularly spaced times for each ranked item. We use the little‐known method of barycentric rational interpolation to interpolate between the strength parameters so that a competitor's strength can be evaluated at any time. We chose the time‐varying strengths to evolve deterministically rather than stochastically, a preference that we reason often has merit. There are many statistical and computational problems to overcome on fitting anything beyond ‘toy’ data sets. The methodological innovations here include a method for maximizing a likelihood function for many parameters, approximations for modelling tied data and an approach to the elimination of secular drift of the estimated ‘strengths’. The methodology has obvious applications to fields such as marketing, although we demonstrate our approach by analysing a large data set of golf tournament results, in search of an answer to the question ‘who is the greatest golfer of all time?’     

Policy Learning for Flood Mitigation: A Longitudinal Assessment of the Community Rating System in Florida

Floods continue to inflict the most damage upon human communities among all natural hazards in the United States. Because localized flooding tends to be spatially repetitive over time, local decisionmakers often have an opportunity to learn from previous events and make proactive policy adjustments to reduce the adverse effects of a subsequent storm. Despite the importance of understanding the degree to which local jurisdictions learn from flood risks and under what circumstances, little if any empirical, longitudinal research has been conducted along these lines. This article addresses the research gap by examining the change in local flood mitigation policies in Florida from 1999 to 2005. We track 18 different mitigation activities organized into four series of activities under the Federal Emergency Management Agency's (FEMA) Community Rating System (CRS) for every local jurisdiction in Florida participating in the FEMA program on a yearly time step. We then identify the major factors contributing to policy changes based on CRS scores over the seven-year study period. Using multivariate statistical models to analyze both natural and social science data, we isolate the effects of several variables categorized into the following groups: hydrologic conditions, flood disaster history, socioeconomic and human capital controls. Results indicate that local jurisdictions do in fact learn from histories of flood risk and this process is expedited under specific conditions.     

椭圆气缸内燃机的稳流试验及其性能预测

本次稳流试验用来预测新颖的椭圆气缸往复式内燃机的性能。实测数据和分析结果表明,椭圆截面气缸内燃机此起等容积正圆截面气缸内燃机,增大了进、排气门,从而提高了充气效率;或在充气效率不减的条件下,大幅度提高转速或增压,以实现发动机的高强化。