信用评级失灵的历史考察和理性思考

信用评级机构在次贷危机中的失败表现备受指责,严格监管的呼声日益高涨。评级失灵并非仅仅开始于安然事件,本文从历次影响较大的评级失灵的事件出发,对信用评级的治理机制进行了理性的思考,声誉机制和政府监管都具有一定的局限,加强政府监管的同时应保持信用评级机构的独立性。     

A qualitative analysis of suicide risk factors,preferred means,and means restriction feasibility within a homeless shelter environment

Suicide completion rates among homeless individuals are approximately nine times higher than the general population. The purpose of this study was to capture the state of social support among homeless individuals, understand how homeless community members support peers in crisis, examine the awareness of suicidal ideation, identify common methods for suicide, and generate strategies for means restriction within a shelter. Twenty individuals residing at an emergency shelter were interviewed. Participants were of diverse cultural identities overrepresented in the sample relative to the general population. Interviews revealed that 40% of participants lacked social support. However, the majority indicated that if they encountered someone at risk for suicide, they would provide support and encouragement to the at-risk individual. Almost half of participants reported knowing of an individual in the shelter who had previously attempted suicide and/or was currently or previously feeling suicidal. Overdose was identified as a primary method for suicide; however, the majority of participants were unable to generate strategies for means restriction. The present study offers a glimpse into the experience of homeless individuals and provides valuable information regarding risk factors for suicide within this highly marginalized and underserved population.     

Meta-analysis of Proportions of Rare Events–A Comparison of Exact Likelihood Methods with Robust Variance Estimation

The conventional random effects model for meta-analysis of proportions approximates within-study variation using a normal distribution. Due to potential approximation bias, particularly for the estimation of rare events such as some adverse drug reactions, the conventional method is considered inferior to the exact methods based on binomial distributions. In this article, we compare two existing exact approaches—beta binomial (B-B) and normal-binomial (N-B)—through an extensive simulation study with focus on the case of rare events that are commonly encountered in medical research. In addition, we implement the empirical (“sandwich”) estimator of variance into the two models to improve the robustness of the statistical inferences. To our knowledge, it is the first such application of sandwich estimator of variance to meta-analysis of proportions. The simulation study shows that the B-B approach tends to have substantially smaller bias and mean squared error than N-B for rare events with occurrences under 5%, while N-B outperforms B-B for relatively common events. Use of the sandwich estimator of variance improves the precision of estimation for both models. We illustrate the two approaches by applying them to two published meta-analysis from the fields of orthopedic surgery and prevention of adverse drug reactions.     

The pattern of birth spacing during Taiwan's demographic transition

This paper considers the impact of an extended family structure on the fertility behavior of married women in Taiwan. A sequential duration model is applied to identify the differences in fertility behavior during the early and latter stages of a woman's reproductive period. Heterogeneity adjustments which correct the respondent-specific characteristics are also implemented. It is found that living with the husband's parents has an impact on the wife's fertility only at the early stage of her childbearing period, and that the subjective son preferences together with the objective fact of no son in the previous 2 births do force a wife to expedite her third birth. These results are robust across different cohorts during the demographic transition and under different specifications of hazard functions. We thank an anonymous referee for his or her valuable comments and suggestions. Responsible editor: Junsen Zhang.     

Coresidence With Elderly Parents: A Comparative Study of Southeast China and Taiwan

Using recent survey data from the Panel Study of Family Dynamics (PSFD) on 1,655 married persons born in 1964-1976 in southeastern China and Taiwan, we studied coresidence with elderly parents using a multinomial probit model for coresidence type and an ordered probit model for residential distance. The study yielded four findings: (a) Patrilocal coresidence was more prevalent in Taiwan than in China; (b) matrilocal coresidence was more prevalent in China; (c) practical factors mattered in both places; (d) in Taiwan only, a couple's economic resources facilitated breaking away from patrilocal coresidence. The findings suggest that, although economic development does not necessarily result in less traditional familial culture, personal economic resources may enable individual couples to deviate from tradition.     

机场运营效率的组合评价方法研究

为了客观准确地评价机场运营效率,在综合BP神经网络的单一综合评价方法和灰色关联度分析的灰色综合评价方法优点基础上,提出了基于评价值方差最小化的机场运营效率组合评价方法。首先界定机场运营效率的内涵,建立了机场运营效率评价指标体系,运用组合赋权法确定各层次指标权重。分析结果表明,评价指标体系科学合理,组合评价方法适用于机场运营效率的评价问题,评价结果能够客观地反映机场运营效率的总体水平。     

Semi-online scheduling on 2 machines under a grade of service provision with bounded processing times

We study the problem of semi-online scheduling on 2 machines under a grade of service (GoS). GoS means that some jobs have to be processed by some machines to be guaranteed a high quality. The problem is online in the sense that jobs are presented one by one, and each job shall be assigned to a time slot on its arrival. Assume that the processing time p _i of every job J _i is bounded by an interval [a,α a], where a>0 and α>1 are two constant numbers. By knowing the bound of jobs’ processing times, we denote it by semi-online problem. We deal with two semi-online problems.     

铁凝“三垛”叙事学解读

铁凝的"三垛"蕴含着丰富的叙事策略,其别出心裁的镜像叙事,循环论时间观念的文本显现,多种叙事模式的交叉运用,深刻地表达了作者对历史、现实和人的命运的深度思考。由于独特的叙事策略的运用,铁凝的"三垛"在其创作中占有重要地位,它以独特的审美风貌丰富了新时期文学创作。     

加强党委办公室作风建设的几点思考

各级党委办公室是党联系人民群众的"纽带",是反映党委工作状况和精神面貌的"窗口".加强党委办公室作风建设,前提是加强爱岗敬业教育,重点是内强素质、外树形象.