ISO 3951-4:2011通过可用于评估实体（批次、过程等）的质量水平是否符合声明值的变量，制定了抽样计划和程序。抽样计划的设计应确保其运行特性曲线与ISO 2859-4中相应属性计划的运行特性曲线尽可能匹配，以便在使用属性抽样和变量抽样之间进行选择时，不会受到增加接受错误申报质量水平的机会的影响。在ISO 3951的这一部分中，与正确声明的质量水平相矛盾的风险在1.4%到8.2%之间。风险是10%的不符合与限定质量比有关的不正确的申报质量水平。 针对三个级别的鉴别能力，以及未知和已知过程标准偏差的情况，提供了相应的抽样计划。 与ISO 3951其他部分中的程序不同，ISO 3951-4:2011中的程序不适用于批次验收评估。一般来说，评估程序中得出错误结论的风险平衡不同于验收抽样程序中的平衡。 ISO 3951-4:2011可用于各种形式的质量检验，在这种情况下，通过检验样品来提供符合某些声明质量水平的客观证据。 该程序适用于允许从实体中随机抽取单个项目样本的实体，如批次、过程输出等。 提供的抽样计划适用于但不限于多种产品的检验，例如:最终产品；零部件和原材料；操作；在制材料；库存物资；维护操作；数据或记录；行政程序。 当质量特征是独立且正态分布的可测量变量，且感兴趣的数量是不合格项目的分数时，可使用本程序。

ISO 3951-4:2011 establishes sampling plans and procedures by variables that can be used to assess whether the quality level of an entity (lot, process, etc.) conforms to a declared value. The sampling plans have been devised so that their operating characteristic curves match those of the corresponding attributes plans in ISO 2859-4 as closely as possible, so that the choice between using sampling by attributes and sampling by variables is not influenced by attempts to increase the chance of accepting an incorrectly declared quality level. In this part of ISO 3951, there is a risk of between 1,4 % and 8,2 % of contradicting a correct declared quality level. The risk is 10 % of failing to contradict an incorrect declared quality level which is related to the limiting quality ratio. Sampling plans are provided corresponding to three levels of discriminatory ability, and for the cases of unknown and known process standard deviation. In contrast to the procedures in the other parts of ISO 3951, the procedures in ISO 3951-4:2011 are not applicable to acceptance assessment of lots. Generally, the balancing of the risks of reaching incorrect conclusions in assessment procedures will differ from the balancing in the procedures for acceptance sampling. ISO 3951-4:2011 may be used for various forms of quality inspection in situations where objective evidence of conformity to some declared quality level is to be provided by means of inspection of a sample. The procedures are applicable to entities such as lots, process output, etc. that allow random samples of individual items to be taken from the entity. The sampling plans provided are applicable, but not limited, to inspection of a variety of products such as: end items; components and raw materials; operations; materials in process; supplies in storage; maintenance operations; data or records; administrative procedures. The procedures are intended to be used when the quality characteristics are measurable variables that are independent and normally distributed, and where the quantity of interest is the fraction of items that are nonconforming.