Admissible minimum bias estimation of response surfaces

The minimum bias estimator was introduced as an alternative to the least squares estimator for approximating response functions by low-order polynomials. Here we show how to obtain an admissible estimator with smaller squared bias.     

论教师道德的底线

在人类道德发展史上,教师道德无论是从职业行为规范方面还是在个人道德修养上始终被认为应处于社会的最高水准,代表着社会道德修养的最高层次。教师道德在追求崇高的价值目标的同时,更要坚守教师道德的底线。教师道德的底线是教师职业活动中必须坚守的最低的道德要求。教师与学生的关系是教师道德所调节的伦理关系中最根本、核心的利益关系,相对于教师的利益,学生的利益具有道德上的优先性,学生利益的优先性就决定了教师道德的底线是,教师在任何时候都不能够损害学生的正当合法利益。     

Estimating with percentile grouped and truncated date from a scale parameter distribution

Data which is grouped and truncated is considered. We are given numbers n₁<…<n_k=n and we observe X_ni ),i=1,…k, and the tottal number of observations available (N> n_k is unknown. If the underlying distribution has one unknown parameter θ which enters as a scale parameter, we examine the form of the equations for both conditional, unconditional and modified maximum likelihood estimators of θ and N and examine when these estimators will be finite, and unique. We also develop expressions for asymptotic bias and search for modified estimators which minimize the maximum asymptotic bias. These results are specialized tG the zxponential distribution. Methods of computing the solutions to the likelihood equatims are also discussed.     

Modeling Endogenous Mobility in Earnings Determination

ABSTRACT

We evaluate the bias from endogenous job mobility in fixed-effects estimates of worker- and firm-specific earnings heterogeneity using longitudinally linked employer–employee data from the LEHD infrastructure file system of the U.S. Census Bureau. First, we propose two new residual diagnostic tests of the assumption that mobility is exogenous to unmodeled determinants of earnings. Both tests reject exogenous mobility. We relax exogenous mobility by modeling the matched data as an evolving bipartite graph using a Bayesian latent-type framework. Our results suggest that allowing endogenous mobility increases the variation in earnings explained by individual heterogeneity and reduces the proportion due to employer and match effects. To assess external validity, we match our estimates of the wage components to out-of-sample estimates of revenue per worker. The mobility-bias-corrected estimates attribute much more of the variation in revenue per worker to variation in match quality and worker quality than the uncorrected estimates. Supplementary materials for this article are available online.     

Half-sample variance estimation

This paper studies an alternative to the jackknife variance estimator, the half-sample variance estimator. Both theoretical and Monte Carlo comparisons between the half-sample variance estimator and the jackknife variance estimator indicate that the former is better in some situations.     

First‐order bias correction for fractionally integrated time series

Most of the long memory estimators for stationary fractionally integrated time series models are known to experience non‐negligible bias in small and finite samples. Simple moment estimators are also vulnerable to such bias, but can easily be corrected. In this article, the authors propose bias reduction methods for a lag‐one sample autocorrelation‐based moment estimator. In order to reduce the bias of the moment estimator, the authors explicitly obtain the exact bias of lag‐one sample autocorrelation up to the order n⁻¹. An example where the exact first‐order bias can be noticeably more accurate than its asymptotic counterpart, even for large samples, is presented. The authors show via a simulation study that the proposed methods are promising and effective in reducing the bias of the moment estimator with minimal variance inflation. The proposed methods are applied to the northern hemisphere data. The Canadian Journal of Statistics 37: 476–493; 2009 © 2009 Statistical Society of Canada     

Are Private Interests Clouding the Peer-Review Process of the WHO Bulletin? A Case Study

Readers’ trust on the medical literature has been eroded, and journal editors and some editorial boards are taking measures to ensure that authors fully and accurately report research findings and disclose conflicts of interest. This article describes a case study in which the papers editor of the World Health Organization (WHO) Bulletin influenced the content of an article that had been approved by the external reviewers. The editor objected to the publication of the large price differentials of the new molecular entities (NMEs) across the Latin American countries where they had been tested and the limited added therapeutic value of the NMEs that had been assessed by independent drug bulletins. This article summarizes the exchanges with WHO staff and posits the hypothesis that the WHO Bulletin might be affected by the shifts in WHO financing. Several authors have raised concern about the impact of financial conflicts of interest in WHO activities in the field of nutrition, intellectual property, and in the emergency response to the flu pandemic. Moreover, it has been reported that powerful WHO contributors pressured WHO into revising its publication policy. This is the first time that authors question if these conflicts of interest are also affecting the editorial independence of the WHO Bulletin.     

英美社会工作“实务模式”的历史演变轨迹与结构性特征

社工实务模式是观察社会福利制度建设与社工专业发展的最佳视角。英美社工实务模式历史发展过程清晰、特征明显。人文关怀和以人为本色彩浓厚,追求社会公平和旨在恢复服务对象社会功能的目标明确,微观取向的个案工作、个案管理与家庭治疗方法盛行,社会福利性质与福利制度建设背景突出。英美社工实务模式发展现状清晰预示了社工专业发展与社工实务模式的发展方向与发展趋势,对中国社会工作专业发展与社工实务模式建构具有重要启示。     

先秦生涯发展思想论纲——以孔子、庄子为例

在中国生涯发展思想史上,早在先秦时期就有了以国家为本位的职业分工思想,并形成了影响中国至今的"官本位"与"金本位"取向的职业价值观。孔子从时间现象学的角度提出了"生涯历程"理论与"职业锚"思想;庄子最早提出生涯浑沌发展模型,生涯浑沌之特征表现在"人生如梦"与"命运"两个主要方面。     

高压旋喷桩在隧道洞顶地表和洞口基地加固中的应用

当前我国大力发展西南地区客运专线项目建设,该地区属云贵高原,山高坡陡,线路设计隧道所占比例较大,沪昆项目隧道所占比例接近70%。隧址区存在地质复杂、地形多变、隧道进出口多存在浅埋、偏压及软弱围岩、洞口基地软基等地质危害,利用高压旋喷桩施工技术对隧道洞口洞顶及基地进行加固,为安全进洞施工及明洞施工提供了安全保证,其中明洞段软基处理可以尽早防治线路工程下沉、冒泥、弹簧土等严重危害运营安全的工程病害。