A note on acceptance sampling for variables

For 60 years acceptance sampling by variables has been recommended as an economic alternative to attribute sampling. Entry in the industrial practice happened after these plans were adopted in 1957 as Military Standard 414 by the US Army. Nowadays a slightly modified version of Mil-Std-414 is known as ANSI/ASQC Z1.9 or as International Standard ISO 3951. In this paper it is shown that the derivation of sampling plans by variables is based on assumptions which don’t hold, that acceptance sampling by variables is inappropriate, and that it doesn’t constitute an alternative to attribute sampling.     

环境监测中大气采样技术研究

随着社会的逐渐发展,人们的环保意识逐渐增强,尤其是大气环境的监测力度呈现增长趋势。大气采样是环境监测的重要环节。在新时期,大气环境污染状态越来越复杂,对人们的身体健康造成不利影响,因此,需要进一步完善大气采样技术,才能保障大气采样的全面性,为提升监测结果的准确性提供保障。论文主要对环境监测中大气采样技术相关内容进行研究,旨在进一步提升大气环境监测效果,为大气环境治理工作的开展提供依据。     

基于谱分析的连续加工过程检验批量的确定

在连续加工过程中 ,合理地确定检验批量 ,不仅可以反映加工过程的稳定性 ,而且也是确定抽样检验方案及检验频次的基础。本文主要利用时间序列的谱分析方法对连续加工过程的质量检测数据进行周期划分 ,从而确定抽样检验的批量 ,并根据周期分析结果 ,指出了导致加工质量产生波动的一些原因。     

顶空气相色谱法测定pvc中的残留氯乙烯单体含量的探讨

测定pvc中的残留氯乙烯单体含量,国标GB/T 4615-2008中采用手动平衡和手动自顶空取样,此方法人为因素干扰多,试验结果重复性差,样品平衡温度不稳定,本文采用自动顶空进样器进样,压力平衡进样技术,使用全封闭传输系统,顶空样品在毛细管线中无扩散;顶空样品在进样过程中无载气稀释,很大程度减少了样品平衡条件的变化,免除了用水浴锅恒温的繁琐步骤。本文的顶空进样器采用压力平衡进样技术以保证得到窄的色谱峰形。可以提供更高的检测灵敏度和确保分析结果的重现性和准确性。     

The effect of sampling mode on response rate and bias in elite surveys

Quality & Quantity - The literature frequently recommends purposive sampling of elites based on the assumptions that random sampling negatively affects the response rate and that it induces...     

水质监测中现场空白样影响因素研究

文章通过考察现场空白样采集过程的各个环节,研究出现分析结果随机性偏高的影响因素。结果表明,对于氨氮测定项目,现场暴露、运输过程以及现场加固定剂环节均会造成一定程度的空白偏高,但不是主要因素。F检验和t检验也表明采样环节不同的空白样,其分析结果精密度与准确度无显著差异。对于汞和镉测定项目,就所采集样本总体来说空白偏高主要来源于瓶子的清洁度,应建立和加强容器抽检制度,规范清洗操作。     

Determining the impact of age and LOS on job satisfaction: a case study of Pakistan automotive industry

This research was conducted to ascertain the impact of age and length of service (LOS) on job satisfaction in engineers of Pakistan public sector. Field survey was conducted using job satisfaction survey (JSS) questionnaire having closed-ended questions. Multistage sampling was conducted using a combination of cluster sampling, stratified sampling and random sampling techniques. Power and Precision software was used to determine the sample size. JSS questionnaires were administered amongst 225 electrical and mechanical engineers from five public sector organizations. 158 usable questionnaires were received and data were analyzed in SPSS. Statistical analyses showed existence of an open mouth U-shaped relationship between LOS/age and job satisfaction. It was found that age moderates relationship between LOS and job satisfaction. Non-responsiveness of senior engineers led to one of the limitations of this study. Results of this study can be used for policy-making decisions.     

开展物资质量监督及专项抽检的必要性

本文首先探讨专项抽检的概念和内容,继而分别从人力资源建设、绩效考核与控制等方面阐述专项抽检工作的实施策略。旨在通过强化物资检验力度来提高物资质量,促进电网建设有序运行。     

A Destructive Sampling Method Designed for Outsourcing Situations Involving High Quality Production Processes

In outsourcing situations involving manufacturing and assembly, the sampling of units produced is important since in many situations not all of the units can be tested. Destructive sampling, which commonly occurs in the assembly and manufacturing industry, is a form of sampling where all units produced cannot be tested since the parts are destructively tested. In this situation, sampling techniques are used to determine if an entire lot should be accepted or rejected based on the sampling results. The traditional sampling techniques include single or classical sampling, double sampling, multiple sampling, skip-lot sampling, chain sampling and MIL-STD-105E. The purpose of this paper is to develop a sophisticated technique that monitors quality at a lower cost than traditional methods yet has similar monitoring characteristics in situations where quality is high and tests are destructive. The proposed technique, Destructive Sampling Method for High Quality production processes (DSM-HQ), is based on a cost function, which balances the costs of sampling versus the costs of finding a defect on the field. DSM-HQ assumes to have a Poisson process defect pattern and uses an Empirical Bayesian analysis to allow the researcher to include prior knowledge.     

Sampling from overlapping subpopulations

Summary Statistical problems in connection with classified data, stratified sampling, cluster sampling and two-stage sampling may be formulated in terms of overlapping subpopulations instead of disjoint classes, strata, clusters or primary sampling units. The introduction in section 1 serves to unify the notation to be used and to exemplify the type of problems that are to be generalized. Samples where the units are classified into overlapping classes are studied in section 2. The applicability is illustrated with an estimation problem in connection with destructive tests. Section 3 treats sampling from overlapping strata and estimation of the sizes of the intersections. Section 4 discusses problems in conjunction with sampling of overlapping clusters. Graphs or networks representing populations with binary relationships are used to exemplify sampling of overlapping clusters. Section 5 is devoted to some examples of two-stage sampling where the primary sampling units are overlapping subsets.     

Estimation in sampling on two successive occasions

For estimating the mean of a finite population on the second of two successive occasions from a simple random sample, the authors [1] have proposedelsewhere an estimate which utilizes the data obtained from the sample on the first occasion as ancillary information. In this paper, it is shown that this estimate is more efficient than the one similar to that of P athak and R ao [2] in all situations where the well known ratio estimate in simple random sampling is no less efficient than the usual regression estimate or the R ao -H artley -C ochran estimate in sampling with varying probabilities and without replacement.     

人口普查净误差估计中的双系统估计量研究

评估普查计数的完整性已经成为五年或十年一次的人口普查不可分割的一部分。评估通常采取质量评估调查的方式。该调查建立在双系统估计量基础上。考虑到普查登记质量及人口移动因素,这三份人口登记名单可提供7个总体指标。由于质量评估调查采取抽样的方式进行,所以这些总体指标要用样本来构造其估计量。基于复杂抽样方法形成的双系统估计量没有现成的方差公式计算其方差。通常使用分层刀切方差估计量近似计算双系统估计量的方差。这需要计算第一步所有样本抽样单位的复制权数。本文将对双系统估计量构造的各个环节进行理论与实践相结合的阐述,深入解析其中深层次的理论问题,为基础理论研究做出贡献,另外也将探讨基于双系统估计量的合成估计量在区域人口数目估计中的应用问题。     

Mixed random systematic sampling designs

In this paper, an alternative sampling procedure that is a mixture of simple random sampling and systematic sampling is proposed. It results in uniform inclusion probabilities for all individual units and positive inclusion probabilities for all pairs of units. As a result, the proposed sampling procedure enables us to estimate the population mean unbiasedly using the ordinary sample mean, and to provide an unbiased estimator of its sampling variance. It is also found that the suggested sampling procedure performs well especially when the size of simple random sample is small. Received August 2001     

Procedures to determine optimum two-stage sampling plans by attributes

Summary In order to compare two sampling plans we use the minimax regret principle, i.e. the minimax principle applied to regret functions. It is shown that among all two-stage sampling plans there exists an optimum sampling plan which can be computed with the aid of a procedure presented in this paper; furthermore another procedure is described how to obtain an approximately optimum two-stage sampling plan in a more direct way. Finally only those two-stage sampling plans are regarded which satisfy an additional condition; among these sampling plans an optimum one exists and is to be determined, too.     

Survey Estimates by Calibration on Complex Auxiliary Information

In the last decade, calibration estimation has developed into an important field of research in survey sampling. Calibration is now an important methodological instrument in the production of statistics. Several national statistical agencies have developed software designed to compute calibrated weights based on auxiliary information available in population registers and other sources. This paper reviews some recent progress and offers some new perspectives. Calibration estimation can be used to advantage in a range of different survey conditions. This paper examines several situations, including estimation for domains in one‐phase sampling, estimation for two‐phase sampling, and estimation for two‐stage sampling with integrated weighting. Typical of those situations is complex auxiliary information, a term that we use for information made up of several components. An example occurs when a two‐stage sample survey has information both for units and for clusters of units, or when estimation for domains relies on information from different parts of the population. Complex auxiliary information opens up more than one way of computing the final calibrated weights to be used in estimation. They may be computed in a single step or in two or more successive steps. Depending on the approach, the resulting estimates do differ to some degree. All significant parts of the total information should be reflected in the final weights. The effectiveness of the complex information is mirrored by the variance of the resulting calibration estimator. Its exact variance is not presentable in simple form. Close approximation is possible via the corresponding linearized statistic. We define and use automated linearization as a shortcut in finding the linearized statistic. Its variance is easy to state, to interpret and to estimate. The variance components are expressed in terms of residuals, similar to those of standard regression theory. Visual inspection of the residuals reveals how the different components of the complex auxiliary information interact and work together toward reducing the variance.     

Comparative randomized inverse sampling

According to previous literature, we define randomized inverse sampling for comparing two treatments with respect to a binary response as the sampling that stops when a total fixed number of successes, irrespective of the treatments, are observed. We have obtained elsewhere the asymptotic distributions for the counting variables involved and have shown them to be equivalent to the corresponding asymptotic distributions for multinomial sampling. In this paper, we start deriving the same basic results using different techniques, and we then show how they give rise to genuinely novel procedures when translated into finite sample approximations. As the main example, a novel confidence interval for the logarithm of the odds ratio of two success probabilities can be constructed in the case of comparative randomized inverse sampling. Some advantages over the standard multinomial sampling in terms of coverage probabilities are visible when no adjustment for cells with zero counts is applied; otherwise, the two sampling schemes appear to be fairly equivalent. This is a reassurance that under certain circumstances, inverse sampling can be safely chosen over more traditional sampling schemes.     

Approximately optimum two-stage sampling plans

Summary In order to compare two-stage sampling plans we use the minimax regret principle i.e. the minimax principle applied to the corresponding regret functions. In this paper approximation formulas for optimum two-stage sampling plans are derived in the case of sampling by attributes as well as in the case of sampling by variables; furthermore a method is presented how to improve the approximate solution in the first case.     

双侧限“σ”法抽样方案的设计（均值）——关于GB／T8054—2008表2的设计建议

文章利用文献[1]中的理论公式和数据表，给出了以均值为质量指标的双侧限“σ”法抽样方案表。该抽样方案表的设计是对GB／T8054—2008表2的改进，不仅符合设计目标，而且更便于应用。     

Spatially Balanced Sampling: A Review and A Reappraisal

Spatially distributed data exhibit particular characteristics that should be considered when designing a survey of spatial units. Unfortunately, traditional sampling designs generally do not allow for spatial features, even though it is usually desirable to use information concerning spatial dependence in a sampling design. This paper reviews and compares some recently developed randomised spatial sampling procedures, using simple random sampling without replacement as a benchmark for comparison. The approach taken is design‐based and serves to corroborate intuitive arguments about the need to explicitly integrate spatial dependence into sampling survey theory. Some guidance for choosing an appropriate spatial sampling design is provided, and some empirical evidence for the gains from using these designs with spatial populations is presented, using two datasets as illustrations.     

A note on Hájek’s theory of rejective sampling

Summary Supplementing results of Hájek (1960, 1964) sufficient conditions for Poisson convergence of the Horvitz-Thompson estimator in pps Rejective sampling are obtained.