Double Sampling Ratio-product Estimator of a Finite Population Mean in Sample Surveys

It is well known that two-phase (or double) sampling is of significant use in practice when the population parameter(s) (say, population mean X¯) of the auxiliary variate x is not known. Keeping this in view, we have suggested a class of ratio-product estimators in two-phase sampling with its properties. The asymptotically optimum estimators (AOEs) in the class are identified in two different cases with their variances. Conditions for the proposed estimator to be more efficient than the two-phase sampling ratio, product and mean per unit estimator are investigated. Comparison with single phase sampling is also discussed. An empirical study is carried out to demonstrate the efficiency of the suggested estimator over conventional estimators.     

“危险驾驶”行为不宜独立设罪——对刑法修正案（八）第二十二条的评析

危险驾驶行为有巨大的社会危险性,刑法修正案（八）将飙车、醉酒驾驶等危险驾驶行为纳入刑法打击的范围,迎合了社会公众要求打击此类行为的舆论。但是,单独设立危险驾驶罪有悖刑法谦抑性,会造成刑法规范之间的不协调和实践操作上的困难。通过解释和完善现有刑法规范,完全可以满足对高危驾驶行为进行刑事处罚的需要。因此,在刑法中单设危险驾驶罪没有必要。     

区域主导产业评价指标与数学模型

以现有研究成果为基础,建立了区域主导产业评价指标体系;基于灰色聚类的思想,提出了评价区域主导产业优度的数学模型-定权聚类评估模型,并对河南省武陟县工业主导产业选择进行了实证研究。     

Using quantile averages in matched observational studies

In two observational studies, one investigating the effects of minimum wage laws on employment and the other of the effects of exposures to lead, an estimated treatment effect's sensitivity to hidden bias is examined. The estimate uses the combined quantile averages that were introduced in 1981 by B. M. Brown as simple, efficient, robust estimates of location admitting both exact and approximate confidence intervals and significance tests. Closely related to Gastwirth's estimate and Tukey's trimean, the combined quantile average has asymptotic efficiency for normal data that is comparable with that of a 15% trimmed mean, and higher efficiency than the trimean, but it has resistance to extreme observations or breakdown comparable with that of the trimean and better than the 15% trimmed mean. Combined quantile averages provide consistent estimates of an additive treatment effect in a matched randomized experiment. Sensitivity analyses are discussed for combined quantile averages when used in a matched observational study in which treatments are not randomly assigned. In a sensitivity analysis in an observational study, subjects are assumed to differ with respect to an unobserved covariate that was not adequately controlled by the matching, so that treatments are assigned within pairs with probabilities that are unequal and unknown. The sensitivity analysis proposed here uses significance levels, point estimates and confidence intervals based on combined quantile averages and examines how these inferences change under a range of assumptions about biases due to an unobserved covariate. The procedures are applied in the studies of minimum wage laws and exposures to lead. The first example is also used to illustrate sensitivity analysis with an instrumental variable.     

The zero-inflated Poisson model and the decayed, missing and filled teeth index in dental epidemiology

For frequency counts, the situation of extra zeros often arises in biomedical applications. This is demonstrated with count data from a dental epidemiological study in Belo Horizonte (the Belo Horizonte caries prevention study) which evaluated various programmes for reducing caries. Extra zeros, however, violate the variance–mean relationship of the Poisson error structure. This extra-Poisson variation can easily be explained by a special mixture model, the zero-inflated Poisson (ZIP) model. On the basis of the ZIP model, a graphical device is presented which not only summarizes the mixing distribution but also provides visual information about the overall mean. This device can be exploited to evaluate and compare various groups. Ways are discussed to include covariates and to develop an extension of the conventional Poisson regression. Finally, a method to evaluate intervention effects on the basis of the ZIP regression model is described and applied to the data of the Belo Horizonte caries prevention study.     

Non-parametric estimation of the long-range dependence exponent for Gaussian processes

We consider a class of long-range-dependent Gaussian processes defined in a semiparametric framework. We propose a new estimator of the long-range dependence parameter, based on the integration of the periodogram in two windows. We show that it is asymptotically Gaussian and calculate the rate of convergence. We optimise parameters defining the window function for the minimum mean-square-error criterion. In a Monte-Carlo study, we compare the proposed estimator with previously studied estimators.     

中学英语教学培养学生语感研究

语感意即学习者多方位接触某种语言及其相关文化而产生的一种规律性的感觉.语感能力作为重要能力结构因素贯穿于中学阶段,其影响作用日益增强.中学英语教学要从听说、读、写等三个环节,持之以恒地将语感训练和语感能力的培养贯穿于英语教学的每个环节,采用多种方法和途径,引导学生在一切语言交际中有意识地去感受语感、把握语感、实践语感.     

医学科研项目的风险管理对策研究

医学科研项目存在着投入资金高、研发周期长、失败率高以及实验环节多等特点,其研究结果往往具有不确定性和不可预期性,因此,有必要从项目的风险角度来进行管理,以规避项目过程的风险.文章旨在对医学科研项目风险成因分析的基础上,较为系统地提出项目风险管理对策.根据项目实施流程,设计医学科研项目风险管理流程,具体分析了立项、实施、结题的不同阶段其风险管理的特点,以期为我国逐步形成医学科研项目风险管理的科学方法提供有益的理论参考.     

农业产业链管理与企业质量安全管理效率的关系研究——以蔬菜产业链管理为例

随着农产品质量安全管理日益重要,产业链管理在农业领域的广泛应用,因此有必要在农产品产业链框架下研究农产品质量安全管理。研究构建结构方程模型,探讨合作关系、产业链管理行为、产业链管理绩效以及农产品质量安全管理效率之间的相互关系。研究结果表明,除了合作关系对质量安全管理效率的直接影响不显著外,产业链管理行为、产业链管理绩效对企业质量安全管理效率直接影响都是显著的,因此企业应积极加强产业链管理以保证农产品的质量安全,提高企业的质量安全管理效率。     

我国东西部卫生人力资源对比分析

将我国东、中、西三个区域的经济发展状况与其卫生发展状况进行比较分析,结果显示,不同区域的卫生人力资源分配存在着很大的差别:东部最优,西部最差。研究中结合我国现行卫生体制,提出与我国西部大开发相适应的西部卫生发展战略及补偿方案。