从盈余管理角度对独立董事制度有效性的实证分析

文章通过选取上市公司样本,运用均值检验和相关分析等方法从盈余管理角度对我国独立董事制度的有效性进行了实证分析,得出以下结论:独立董事制度的设立对公司盈余管理没有显著影响;独立董事占董事总数的比例与盈余管理之间也没有显著的相关性;自愿设立独立董事的公司与政策规定设立独立董事的公司两者的盈余管理有显著差异,前者的平均值小于后者的平均值。总体上讲我国独立董事制度没能有效监督公司盈余管理行为,其发挥作用还需以公司自身良好素质做平台。     

我国中等收入群体比重及其特征

中等收入群体的界定标准、规模和特征一直是学术界关注的焦点。在回顾和评述现有各种界定标准的基础上,建议采用全球所有国家收入中位数的67%~200%作为定义我国中等收入群体的上下限。研究发现,近些年我国中等收入群体比重在逐渐提高,从2002年的10%上升到2016年的28.9%,这主要源于我国居民整体收入水平的提高而不是收入分配格局的变化。要扩大我国中等收入群体比重,保持中高速增长至关重要,政策的重点是提“低”而不是限“高”,同时要防范现有的中等收入群体跌落为低收入群体。中等收入群体主要分布在城市地区,收入来源主要是工资性收入,储蓄率偏高,受教育水平明显高于低收入者和贫困人口。中等收入群体的标准下限附近分布着规模客观的低收入者,他们是扩大中等收入者比重的潜在来源,应是政策瞄准的主要对象。     

论科学证据的两种概率解释

在科学证据研究中,存在＂正相关＂和＂高概率＂两种科学证据的概率定义。从这两个定义出发,能够比较清晰直观地解释科学证据的许多相关问题,如科学证据中的＂比较级＂和＂可接受性＂等。然而,两个定义自身存在着不可忽视的缺陷：＂正相关＂不是证据的充要条件,＂高概率＂也不足以使证据之为证据。     

Pseudo-Bayes and pseudo-empirical Bayes estimators in randomized response sampling

In this article, new pseudo-Bayes and pseudo-empirical Bayes estimators for estimating the proportion of a potentially sensitive attribute in a survey sampling have been introduced. The proposed estimators are compared with the recent estimator proposed by Odumade and Singh [Efficient use of two decks of cards in randomized response sampling, Comm. Statist. Theory Methods 38 (2009), pp. 439–446] and Warner [Randomized response: A survey technique for eliminating evasive answer bias, J. Amer. Statist. Assoc. 60 (1965), pp. 63–69].     

Estimating the population proportion in modified ranked set sampling methods

In this paper, proportion estimators and associated variance estimators are proposed for a binary variable with a concomitant variable based on modified ranked set sampling methods, which are extreme ranked set sampling (ERSS), median ranked set sampling (MRSS), percentile ranked set sampling (Per-RSS) and L ranked set sampling (LRSS) methods. The Monte Carlo simulation study is performed to compare the performance of the estimators based on bias, mean squared error, and relative efficiency for different levels of correlation coefficient, set and cycle sizes under normal and log-normal distributions. Moreover, the study is supported with real data application.     

A new estimator of proportion with a linear function using data from two-decks randomized response model

A new estimator for estimating the proportion of a potentially sensitive attribute in survey sampling has been introduced by solving a linear equation. The proposed estimator has been compared with the estimator proposed by Odumade and Singh (2009) with equal protection to all of the respondents. The asymptotic properties of the proposed estimator are investigated through exact numerical illustrations for different choices of parameters. A non randomized response approach has been suggested. A scope for further research has also been pointed out.     

众数测算的一种新方法及其应用

针对传统众数估计值会因为组距的改变而不稳定,在已有的半极差(样本)众数估计方法上,提出多比例极差(样本)众数估计新方法。模拟研究显示,相对于半极差(样本)众数估计方法,该方法估计结果更稳定、准确。在实证分析中,基于2014、2015年国家一体化住户调查数据,使用新方法计算了新疆兵团居民人均可支配收入众数。结果表明,众数可以作为居民人均可支配收入平均数、中位数的有益补充,众数在政府统计中的推广及应用具有一定的可行性与必要性。     

基于粒子群算法与改进Ziegler-Nichols算法的PID整定方法

针对Ziegler-Nichols算法设计的PID控制器阶跃响应不理想,不具有灵活性等缺点,提出基于粒子群算法与改进 Ziegler-Nichols算法的PID整定方法。采用粒子群算法优化了Ziegler-Nichols算法中的幅值和相角,设计了具有更好性能 指标的PID控制器。实验结果表明采用该方法进行参数整定后的PID控制器响应速度较快,降低了系统的超调量。     

立体标签自动贴标机结构设计

为了减少在产品包装环节中的人员参与,提高包装环节的自动化程度,研制了一种用于立体标签的自动贴标机。 根据产品贴标的流程,采用Pro/E软件进行三维建模和零部件的优化设计,包括传送机构、标签推进机构和折弯机构。 折弯机构中采用了折弯翻板实现对标签的折弯控制;自动贴标机各机构均采用了独立的电机控制,控制系统采用PLC 技术和变频器调速控制,设计了电动机正反转的控制电路图。通过对机械结构和电气控制系统优化设计,得到了满足设 计要求的自动贴标机机构设计参数,实现了对厚度为0.5 mm纸质标签纸的2次折弯并实现贴标过程。该自动标签机的 使用实现了包装过程的自动化,提高产品的包装效率。     

The umvue and bayes estimate of reliability of mixed failure time distribution

We study the reliability estimates of the non-standard mixture of degenerate (degenerated at zero) and exponential distributions. The Uniformly Minimum Variance Unbiased Estimator (UMVUE) and Bayes estimator of the reliability for some selective prior when the mixing proportion is known and unknown are derived. The Bayes risk is computed for each Bayes estimator of the reliability. A simulated study is carried out to assess the performance of the estimators alongwith the true and Maximum Likelihood Estimate (MLE) of the reliability. An example from Vannman (1991) is also discussed at the end of the paper.