标准编号：ISO 8423:2008
中文名称：不合格品率的计量序贯抽样检验程序（标准差已知）
英文名称：Sequential sampling plans for inspection by variables for percent nonconforming (known standard deviation)
发布日期：2008-09
标准范围
This International Standard specifies sequential sampling plans and procedures for inspection by variables ofdiscrete items.The plans are indexed in terms of producers risk point and the consumer's risk point. Therefore, they aresuitable not only for the purposes of acceptance sampling, but for the more general purpose of the testing ofsimple statistical hypotheses for proportions.The purpose of this International Standard is to provide procedures for the sequential assessment ofinspection results that may be used to induce the supplier to supply lots of a quality having a high probabilityof acceptance. At the same time, the consumer is protected by a prescribed upper limit to the probability ofaccepting a lot (or process) of poor quality.This International Standard is primarily designed for use under the following conditions:a) where the inspection procedure is to be applied to a continuing series of lots of discrete products all supplied by one producer using one production process. In such a case, sampling of particular lots is equivalent to the sampling of the process. If there are different producers or production processes, this International Standard shall be applied to each one separately;b) where only a single quality characteristic x of these products is taken into consideration, which must be measurable on a continuous scale;c) where the measurement error is negligible (i.e. with a standard deviation no more than 10 % of the process standard deviation);d) where production is stable (under statistical control) and the quality characteristic x has a known standard deviation, and is distributed according to a normal distribution or a close approximation to the normal distribution;e) where a contract or standard defines an upper specification limit U, a lower specification limit L, or both; an item is qualified as conforming if and only if its measured quality characteristic, x, satisfies the appropriate one of the following inequalities: 1) x ≤ U(i.e. the upper specification limit is not violated); 2) x ≥L (i.e. the lower specification limit is not violated); 3) x ≤ U and x≥ L (i.e. neither the upper nor the lower specification limit is violated).Inequalities 1) and 2) are called cases with a "single specification limit", and 3) is the case with "doublespecification limits".
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