On certain unbiased product estimators

When data on an auxiliary variate is available on all the units of the population, negatively correlated with the study variate, Robson (1957) and Murthy (1964) proposed product method of estimation for the estimation of the population total (mean) of the study variate. In this paper, we discuss a method given in Rao (1983) and obtain a simpler dervation of the class of unbiased product estimators for the case of Simple Random Sampling WithOut Replacement design as well as for the case of interpenetrating subsamples design which follows as a limiting case. Finally, we shall illustrate the results by means of two simple numerical example from live data.     

Relationships among moments of order statistics in samples from two related outlier models and some applications

Balakrishnan (1987a) has recently shown that the moments of order statistics in samples drawn from a continuous population with pdf f(x) symmetric about zero comprising a single outlier with pdf g(x) also symmetric about zero can be expressed in terms of the moments of order statistics in samples drawn from the population obtained by folding the pdf f(x) at zero and the moments of order statistics in samples drawn from the population obtained by folding the pdf f(x) at zero comprising a single outlier with pdf obtained by folding g(x) at zero. The cumulative round off error involved in the numerical evaluation of the moments of order statistics from the symmetric outlier model, using a table of the moments of order statistics from the folded population and the moments of order statistics from the folded outlier model, has also been studied by Balakrishnan (1987a) and shown to be not serious. Making use of these results we study here the robustness of some estimators of th location and scale parameters of a double exponential distribution.     

Identities and recurrence relations for order statistics corresponding to ncnidentically distributed variable

In this paper, we derive two simple identities and some recurrencerelations involving order statistics from a sample of size n in case there is a possibility of one or more outliers being present.     

A study of ratio and product estimators under a super population model

In this paper ratio and product estimators are studied under a super population model considered by Durbin (1959. Biometrika) where a regression model of y (the characteristic variablel on x(the auxiliary variable) is assumed. The comparison of the ratio and the product estimators have been made in the literature (see Chaubey, Dwivedi and Singh (1984), Commun. Statist. - Theor. Meth.) When the auxiliary variable has a gamma distribution. In this paper similar analysis has been carried out when the auxiliary variable has an inverse Gaussian distribution.     

Simultaneous Logit-Based Confidence Intervals for Odds Ratios in 2 × k Classification Tables with a Fixed Reference Level

In this article, we consider the problem of constructing simultaneous confidence intervals for odds ratios in 2 × k classification tables with a fixed reference level. We discuss six methods designed to control the familywise error rate and investigate these methods in terms of simultaneous coverage probability and mean interval length. We illustrate the importance and the implementation of these methods using two {sc hiv} public health studies.     

市场激励、农地确权与农户农地质量保护行为

基于黄土高原苹果优势区771个苹果户实地调研数据,采用Probit和Tobit模型考察市场激励、农地确权对农户农地质量保护行为的影响及作用机理,并进行稳健性检验。研究表明：农户农地质量保护行为受到农产品市场和农地市场的双重激励,短期内对农地产出贡献相对较高的保护行为主要受到农产品市场激励,长期内对农地质量贡献相对较高的保护行为主要受到农地市场激励;农地确权对长期保护行为具有正向激励效应,但对短期保护行为的影响不显著;农地确权在农户农地质量保护行为的农地市场激励中存在负向调节效应。政府应注重完善农地市场制度、农地价格机制以及要素市场运行机制,同时重视农地确权改革宣传和信息披露,有效发挥农地市场和农地确权对农地质量保护行为的正向激励效应。     

控股股东持股比例如何影响企业生产率

企业生产率的持续提升可以帮助企业在激烈的市场竞争中获得超额利润,进而为股东创造出更高的价值。基于2007—2018年中国上市公司的数据,研究了控股股东持股比例对企业生产率的影响。研究结果表明,控股股东持股比例的提升促进了企业生产率的改善。进一步对作用机制进行研究发现,在分析师跟踪更少、产品市场竞争程度更低、小事务所审计的企业中,控股股东持股比例对企业生产率的促进作用更加明显,表明控股股东持股比例的提高可以通过“监督效应”促进企业生产率。监管部门应充分意识到股权结构对企业生产率的影响,进一步加强投资者保护；上市公司也应更加注重完善治理水平,不断优化股权结构,提升企业生产率。     

中国木质林产品隐含碳排放影响因素动态分析

以2002、2007和2012年投入产出数据为依据,计算了我国木质林产品行业的隐含碳排放,并应用LMDI分解法对木质林产品行业的隐含碳排放变化影响因素进行了动态分析。结果显示,我国隐含碳排放量呈上升趋势,木质林产品行业的隐含碳排放主要用于出口产品使用,中间产品消耗的碳排放水平比较高,在碳减排方面存在较大的空间。木质林产品行业隐含碳排放的拉动因素按其促进效应的大小依次为：经济产出、人口规模和能源结构,能源强度则是抑制木质林产品行业隐含碳排放增长的主要因素。     

产品市场竞争、高管激励与过度投资的相关关系分析

以2010—2014年我国沪、深两市的3184个上市 A 股面板数据为样本,基于产品市场竞争的视角分析了高管激励对过度投资的影响。结果表明：我国过度投资现象仍然广泛存在,产品市场竞争和高管激励均能抑制企业过度投资行为,并且产品市场竞争越激烈,高管激励对过度投资的影响程度越小,说明我国产品市场竞争和高管激励对过度投资的影响具有相互替代的作用。     

谷物包装自动流水线设计

针对人工作业成本高及过程自动化程度低等问题,设计了谷物进仓、灌装和封口过程的自动化设备。以PLC为 核心的控制系统统一指令实现谷物收割进仓、烘干出仓以及包装称量过程的自动化。利用栅板与弹簧、棘轮构成的动配 合实现稻屑分离;采用新型卡合结构完成谷物包装袋的封口。根据工作过程,确定该系统控制流程,最后对样机进行运 行稳定性实验测试。测试结果表明所设计的流水线能有效实现稻屑分离、撑袋、灌装、称质量和封口过程自动化。该流 水线设计能够满足设计要求,提高工作效率。