Uncertainty of Measurements. Part 1

Proofs are given of the coincidence of the concepts of precision and uncertainty and also of the absence of a problem in choosing between the corresponding concepts of measurement accuracy. It is shown that an estimate of the quality of measurements using the approach of the Guide to the Expression of Uncertainty in Measurement is inferior in accuracy and universality to an estimate using the approach and procedure of the State standard GOST R ISO 5725.     

Uncertainty of Measurements. Part 2

A method is proposed for estimating the precision (uncertainty) of measurements which is based on a combination of the approaches of the Guide to the Expression of Uncertainty in Measurement and the State Standard R ISO 5725.     

Sets and Uncertainty

Arguments are presented indicating coincidence between the concepts of uncertainty and precision, and also on the undesirability of using the uncertainty propagation law for estimating dispersion. It is possible to estimate the reproducibility without performing an interlaboratory experiment and ways are characterized for estimating the closeness between the actual (or true) value of a measured quantity to the measurement result in the presence of influencing factors.We continue the selection of papers from the seminar “Mathematical methods in providing quality and mutual acceptance in measurement results,” with the start of the selection found in Nos. 4 and 5 for 2005.__________Translated from Izmeritel’naya Tekhnika, No. 6, pp. 20–25, June, 2005.     

Expression for the Accuracy of Measuring Instruments in Accordance with the Concept of Uncertainty of Measurements

The present article considers the need to express the accuracy of both standard and working measuring instruments by a standard uncertainty estimated in accordance with type A or type B, or by the combined uncertainty, the permissible uncertainty, or the permissible uncertainty for the confidence level P.     

An Algorithm for Deriving the Measurement Equation and Estimating the Methodological Error (Uncertainty) in the Result for Indirect Measurements

An algorithm is proposed for deriving the measurement equation for indirect measurements, which is based on incorporating the features of the measurement object, the influencing factors in the transformation of the data-bearing signal as it passes from the object to the meter, and also the signal transformation in the meter. An example is given of distance measurement performed by means of electromagnetic waves in the optical range.__________Translated from Izmeritel’naya Tekhnika, No. 4, pp. 25–29, April, 2005.     

Physical Nature of Measurement Uncertainty in Metrology

It is shown that the problem of measurement uncertainty in metrology is many-sided and must be interpreted not only on the basis of the purely statistical processing of data but also taking account of the definition of a physical quantity as a fundamental triad: observable, state, average value. It is shown that inaccuracy and uncertainty are two realities associated with a lack of information concerning the system of knowledge.     

Guidelines for Expressing the Uncertainty of Measurement Results Containing Uncorrected Bias

This paper proposes a method to extend the current ISO Guide to the Expression of Uncertainty in Measurement to include the case of known, but uncorrected, measurement bias. It is strongly recommended that measurement results be corrected for bias, however in some situations this may not be practical, hence an extension of the Guide is proposed to address this special situation. The method keeps with the spirit of the Guide in maintaining the link between uncertainty and statistical confidence. Similarly, the method maintains the transferability of one uncertainty statement to be included as a component in another uncertainty analysis. The procedure involves modifying the calculation of the expanded uncertainty, allowing it to become asymmetric about the measurement value. The method is compared to other alternative procedures, and an illustration of how it affects tolerance zones is presented.     

Calculation of Measurement Uncertainty Using Prior Information

We describe the use of Bayesian inference to include prior information about the value of the measurand in the calculation of measurement uncertainty. Typical examples show this can, in effect, reduce the expanded uncertainty by up to 85 %. The application of the Bayesian approach to proving workpiece conformance to specification (as given by international standard ISO 14253-1) is presented and a procedure for increasing the conformance zone by modifying the expanded uncertainty guard bands is discussed.     

试论测量不确定度与误差理论的关系

以功率测量为例,分别采用经典误差理论及GUM的方法对测量结果进行评价。指出测量不确定度与误差理论的关系--测量不确定度评定取代了经典误差理论中随机误差和未定系统误差的处理,从而成为误差理论的组成部分,是误差理论中相关内容的发展和完善,在评估方法和表达方式上更趋于合理和统一。     

Conditionally true values of measurement results and their role in the metrology of measurement systems

Questions of the uncertainty of indirect measurement results obtained using values that are conditionally taken as true are considered.Translated from Izmeritelnaya Tekhnika, No. 11, pp. 69–70, November 2004.     

Physical Models for Analyzing the Results of Measurements

Conditions for applying a classical determinism model for analyzing and describing measurement are considered. It is shown that if during measurement results may be studied from the position of classical determinism, then it is advisable to use the concept of an error as physically justified determinism. A study of dynamic chaos regimes in deterministic systems and measurement of their parameters is only possible with use of the concept of uncertainty.__________Translated from Izmeritel’naya Tekhnika, No. 6, pp. 25–30, June, 2005.     

普通水准标尺分米分划误差测得值不确定度评定

普通水准标尺主要应用于水准测量。本文依据JJG 8-1991《水准标尺检定规程》和JJF 1059. 1-2012《测量不确定度评定与表示》,建立相应的测量模型,分析了普通水准标尺分米分划误差测量不确定度的来源,对其测量不确定度进行评定。     

抽样引起的测量不确定度评定

若测量值定义为抽样目标中的分析物浓度,那么与抽样相关的不确定性必然导致最终测量结果的不确定度。抽样不确定度主要来源于抽样目标的不均匀性、抽样方案不明确、抽样和样品制备过程中引入的交叉污染、分析物损失等。以欧洲分析化学会的指南为基础,介绍了抽样不确定度评定的经验方法,该方法将测量不确定度来源区分为抽样过程和分析过程中的随机效应与系统效应。通过实例说明了如何通过重复实验和方差分析来量化抽样和分析过程中的随机效应,从而评估抽样和样品制备所引入的不确定度。     

The scope for measuring the effective dose of external irradiation and the use of operational quantities

The effective dose of external radiation may be measured as a physical quantity by an indirect method based on direct measurements of air kerma for photons, neutron fluence, or electron fluence, where calculated conversion factors for given irradiation conditions are used. The same method is used for measuring operational quantities. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 47–52, May, 2008.     

动态随机球的标定误差与测量次数的关系

本文介绍了随机球标定技术的原理。针对随机球标定方法的两种方法(静态法和动态法),本文分别分析了两种方法的标定误差与测量次数之间的关系。依据数理统计原理和合理的假设,理论分析表明静态法是一种特殊的动态法。两种方法的标定误差随测量次数增加呈N-1/2递减。针对动态法,本文进行了动态法随机球标定实验。实验结果表明,动态法的标定误差与测量次数之间近似符合N-1/2规律。     

Uncertainty of Thermal Diffusivity Measurements by Laser Flash Method

The laser-pulse method is a well-established nonsteady-state measurement technique for measuring the thermal diffusivity, a, of solid homogeneous isotropic opaque materials. BNM-LNE has developed its own bench based on the principle of this method in which the thermal diffusivity is identified according to the “partial time moments method.” Uncertainties of thermal diffusivity by means of this method have been calculated according to the ISO/BIPM “Guide to the Expression of Uncertainty in Measurement.” Results are presented for several cases (Armco iron, Pyroceram 9606) in the temperature range from 20 to 800°C. The relative expanded (k = 2) uncertainty of the thermal diffusivity determination is estimated to be from ±3 to ±5%, depending on the material and the temperature. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

混凝土抗渗仪测得值的不确定度评定

抗渗仪是测定混凝土的抗渗性能,适用于建筑企业、科研院校、设计施工等部门从事混凝土抗渗性能的测定研究,同时可用于其它建筑材料透气测定和质量检测.本文分析测量不确定度的来源,对各不确定度进行详细评定,并给出示值误差的不确定度.     

基准等效听阈声压级全国量值比对及数据不确定度分析

基准等效听阈声压级是评定人耳听阈的重要参数。本文简要介绍基准等效听阈声压级量值比对过程、比对测量数据及其不确定度分析。     

手持式激光测距仪"测距标准偏差综合评定"的扩展不确定度

在确定的函数关系(数学模型)中,因变量(输出量)随自变量(输入量)的变化规律完全由数学逻辑所确定,自变量到因变量的传递系数(灵敏系数)也可由因变量的标准差和自变量的标准差之比所决定,而与自变量的来历(测量的或者给定的)没有关系[1].本文根据这一基本原理,采用模拟自变量随机变化的方法,成功计算了手持式激光测距仪的测距固定偏差和比例偏差系数的测量不确定度,从而计算出测距标准差综合评定的扩展不确定度,同时解决了复杂的数学模型中多个输入量到输出量的灵敏系数和输出量的不确定度的计算问题.