ISO 28801:2011 生产方风险质量（PRQ）和使用方风险质量（CRQ）指数化、带有最小样本量属性的二重抽样方案

标准编号：ISO 28801:2011

中文名称：生产方风险质量（PRQ）和使用方风险质量（CRQ）指数化、带有最小样本量属性的二重抽样方案

英文名称：Double sampling plans by attributes with minimal sample sizes, indexed by producer's risk quality (PRQ) and consumer's risk quality (CRQ)

发布日期：2011-03

标准范围

This International Standard provides double sampling plans by attributes for the acceptance inspection of lotsof discrete items. The plans are indexed by the producer's risk quality (PRQ) and the consumer's risk quality(CRQ) where the nominal producer's and consumer's risks are respectively either (5 %, 5 %), (5 %, 10 %) or(10 %, 10 %). Plans are provided for inspection for percent nonconforming and for inspection fornonconformities per 100 items. The lot is accepted if there are no nonconforming items (nonconformities) inthe first random sample, and rejected if it contains two or more nonconforming items (nonconformities). Ifprecisely one nonconforming item is found in the first sample, a second random sample is drawn; the lot isthen accepted if the second sample contains no nonconforming items (nonconformities) and rejectedotherwise.The objective of this International Standard is to provide procedures that enable lot disposition to bedetermined quickly and economically if quality is particularly good or bad. For intermediate quality, a secondsample is drawn in order to be able to discriminate more reliably between acceptable and unacceptable lots.The two sample sizes are chosen to minimize the maximum expected sample size with respect to incomingquality subject to the nominal risks not being exceeded.Similarly, the plans may be used to test the hypothesis that a lot or process quality level is equal to the PRQ(i.e. acceptable) against the alternative hypothesis that the quality level is equal to the CRQ (i.e.unacceptable).The plans are preferable to single sampling plans where the cost of inspection is high, where the delay anduncertainty caused by the possible requirement for second samples is inconsequential and where a relativelylarge ratio of the consumer's risk quality to the producer's risk quality can be tolerated.The plans are suitable for isolated lots or for short series of lots, where the sum of the two sample sizes is nolarger than about 10 % of the size of the lot. The plans are also suitable for continuing series of lots when lotsthat fail to satisfy the acceptance criteria are 100 % inspected and all nonconforming items replaced byconforming items; however, for continuing series of lots, consideration should also be given to using doublesampling plans from ISO 2859-1.The statistical theory underlying the plans, tables and figures is provided in Annex A.

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