1.1 本指南介绍了用于评估和确保用于实验室间和实验室内研究的单个样品和散装材料均匀性的技术和指南。 1.2 本指南适用于用于能力验证计划和实验室间研究的样品和参考材料，以确定测试方法的精度估计。它还可用于与单个实验室内测试质量控制相关的活动。 1.3 提出了五种评估样品均匀性的技术。这五种技术并不是评估样本同质性的可用技术的详尽列表，但选择这些技术是为了涵盖各种类型和目的的实验室研究的一系列情况（以及所需的各种严格程度）。 1.4 前四种技术中的每一种都提供了同质性测试方案和评估同质性测试结果的统计程序。描述了每种技术适用的情况。 1.5 对于无法进行均匀性测试的情况，第五种技术为生产均匀样品提供了指导。 1.6 本指南的附录提供了技术1、2、3和4的示例电子表格。 1.7 本指南不适用于认证标准物质（CRM）或用于校准的材料的评估。 1.8 单位- 未规定本标准的单位制。 本标准中的尺寸量仅作为计算方法的说明。这些示例对所处理的产品或测试方法没有约束力。 1.9 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.10 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本指南介绍了评估和确保单个样品或散装材料均匀性的技术和指南，可用于实验室间或实验室内研究。研究类型包括但不限于确定测试方法精度估计的研究、能力验证计划以及与单个实验室内测试质量控制相关的研究。 5.2 由于任何实验室研究的测试结果都会受到测试样本质量的影响，因此生产同质样本并确定同质程度对于解释研究结果非常重要。 5.3 本指南中介绍了五种技术，用于评估一系列环境和严格程度下的样本同质性。进行研究的环境和要求的严格程度可能不同。用户应考虑每种技术中列出的情况，以确定哪种技术适用于手头的研究。 5.4 当可以对样品进行重复测试时，技术1、2和3中的每种都提供了测试和评估样品均匀性的程序。技术4提供了在无法进行重复测试时评估样本同质性的计划。技术5建议在不可能进行均匀性测试的情况下生产均匀样品的做法。 5.5 当满足样本内和样本间充分均匀性的条件时，多个样本上测试结果的任何差异可以合理地归因于测试变化，而不是样本变化。 5.6 当发现样品内部或之间存在差异，且样品被认为不够均匀时，可以改进或纠正样品制备过程，并制备一组新的样品。或者，在样品同质性无法改善或由于其他原因必须使用样品的情况下，实验室研究的评估方法应考虑样品之间差异的影响。 5.7 当与开发精度估计的研究结合使用时，本标准中的指南可用于帮助量化测试变化的来源（例如由于采样、测试方法重复性和不均匀程度产生的影响），因此，可用于确定和说明精度估计有效的条件。 5.8 对于能力验证项目，本标准中的指南可以提供信息，防止实验室因样本之间的固有差异而受到不公平的惩罚。 5.9 在单个实验室中，本标准中的指南可用于评估样品的均匀性，以用于测量随时间变化的试验，或用于比较不同技术人员进行的试验结果的研究。 5.10 为了尽量减少同质性测试所需的资源，本指南的技术1、2和3中建议使用至少十个样品的测试设计，每个样品上进行两次重复测试。该测试设计用于其他国际标准。参见Ref ( 1. ) 4. 和ISO 13528。当无法进行重复测试时使用的技术4同样建议测试至少10个样本。这并不排除使用10个以上的样本或两个以上的重复。 注1: 本指南中提供的技术1、2和3示例的电子表格显示了对每个样品进行两次重复测试时的计算。 当使用两个以上的重复测试时，可以使用文本中提供的等式调整技术1和2的电子表格。如第9节所述，技术3的使用仅限于重复测试（即， k = 2). 在以下情况下使用技巧3: k >2.重复结果一致性的初步测试可以使用技术1中提出的科克伦试验的一般形式进行，同质性分析可以按照附录中的描述进行， X4.3 . 此外，如果需要，可以将技术3中的同质性标准与使用技术2中所示电子表格的计算一起使用。 5.11 本指南不足以评估认证标准物质或用于校准的材料。尽管要求标准物质具有同质性，但标准物质和校准材料通常需要满足本指南中未提及的其他要求（如可追溯性和不确定度估计）。

1.1 This guide presents techniques and guidance for evaluating and assuring homogeneity of individual samples and bulk materials used for interlaboratory and intra-laboratory studies. 1.2 This guide is applicable to samples and reference materials used for proficiency testing programs and for interlaboratory studies to determine precision estimates for test methods. It may also be useful for activities related to quality control of testing within a single laboratory. 1.3 Five techniques are presented for assessing sample homogeneity. The five techniques are not an exhaustive list of available techniques for assessing homogeneity of samples, but the techniques were chosen to cover a range of circumstances (and various degrees of rigor required) for laboratory studies of various types and purposes. 1.4 Each of the first four techniques provides a scheme for testing for homogeneity and a statistical procedure for evaluating the results of the homogeneity testing. The circumstances are described for which each of the techniques is suited. 1.5 For circumstances when homogeneity testing is not possible, the fifth technique provides guidance for producing homogeneous samples. 1.6 The appendixes of this guide provide example spreadsheets for Techniques 1, 2, 3, and 4. 1.7 This guide is not intended for evaluation of certified reference materials (CRMs) or materials used for calibration. 1.8 Units— The system of units for this standard is not specified. Dimensional quantities in the standard are presented only as illustrations of calculation methods. The examples are not binding on products or test methods treated. 1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 This guide presents techniques and guidance for evaluating and assuring homogeneity of individual samples or bulk materials and can be used for either interlaboratory or intra-laboratory studies. The types of studies include, but are not limited to, studies to determine precision estimates for test methods, proficiency testing programs, and studies related to quality control of testing within a single laboratory. 5.2 Because the test results of any laboratory study are affected by the quality of the samples tested, producing homogeneous samples and determining the degree of homogeneity is important for interpreting the results of the study. 5.3 Five techniques are presented in this guide to evaluate sample homogeneity for a range of circumstances and degrees of rigor. The circumstances under which the studies are conducted and the degree of rigor required may differ. The user should consider the circumstances listed in each technique to determine which is appropriate for the study at hand. 5.4 Each of the Techniques 1, 2, and 3 provides a procedure for testing and evaluating sample homogeneity when replicate testing of the samples is possible. Technique 4 provides a plan to evaluate sample homogeneity when replicate testing is not possible. Technique 5 recommends practices for producing homogeneous samples for circumstances when homogeneity testing is not possible. 5.5 When the conditions of adequate within-sample homogeneity and between-sample homogeneity are satisfied, any differences in test results on multiple samples can reasonably be attributed to testing variation and not due to sample variation. 5.6 When differences within or between samples are discovered and the samples are deemed insufficiently homogeneous, the sample preparation process can be improved or corrected and a new set of samples can be prepared. Or, in cases where the sample homogeneity cannot be improved or for other reasons when the samples must be used, the method of evaluation for the laboratory study should account for the effect of differences between samples. 5.7 When used in conjunction with studies to develop precision estimates, the guidance in this standard can be used to help quantify sources of test variation (such as effects due to sampling, test method repeatability, and the degree of inhomogeneity) and, therefore, can be useful for determining and stating the conditions under which the precision estimates are valid. 5.8 For proficiency testing programs, the guidance in this standard can provide information to prevent laboratories from being unfairly penalized for testing variation due to inherent differences between samples. 5.9 In a single laboratory, the guidance in this standard could be used to evaluate the homogeneity of samples for studies to measure test variation over time or for studies to compare the results of tests performed by different technicians. 5.10 To minimize the resources required for homogeneity testing, a testing design using a minimum of ten samples with two replicate tests performed on each sample is recommended in Techniques 1, 2, and 3 of this guide. This test design is used in other international standards. See Ref ( 1 ) 4 and ISO 13528. Technique 4, used when replicate testing is not possible, similarly recommends testing a minimum of ten samples. That does not preclude the use of more than ten samples or more than two replicates. Note 1: The spreadsheets provided in this guide for the examples in Techniques 1, 2, and 3 show the calculations when two replicate tests are performed on each sample. The spreadsheets shown for Techniques 1 and 2 may be adjusted using the equations provided in the text when more than two replicate tests are used. Use of Technique 3, as presented in Section 9, is limited to duplicate testing (that is, k = 2). To use Technique 3 when k > 2, preliminary testing for consistency of replicate results can be performed using the general form of the Cochran’s Test as presented in Technique 1, and the homogeneity analysis can be performed as described in the Appendix, X4.3 . Also, if desired, the homogeneity criterion in Technique 3 can be used with the calculations using the spreadsheets shown in Technique 2. 5.11 This guide is not sufficient for evaluation of certified reference materials (CRMs) or materials used for calibration. Even though homogeneity is required for CRMs, CRMs and calibration materials are typically subject to additional requirements (such as traceability and estimates of uncertainty) that are not addressed in this guide.