GB/T 2828.2-2008 Sampling procedures for inspection by attributes - Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection (English)
1 Scope GB/T 2828.2 establishes an acceptance sampling inspection system by attributes indexed by limiting quality (LQ) for isolated lot (isolated series lot, isolated lot or single lot) when the switching rules given in GB/T 2828.1 are not applied. The sampling plans provided by this Part of GB/T 2828 are regarded as the supplement of GB/T 2828.1 and compatible with GB/T 2828.1. The plans in this Part of GB/T 2828 are indexed by a preferred series of limiting qualities (LQ) with a consumer’s risk usually below 10 %, but only below 13 % in two circumstances. This method of indexing is more convenient than the special procedures for limiting quality protection in GB/T 2828.1. Note: the plans in GB/T 2828.1 are indexed by a preferred series of AQL values and inspection levels. During the inspection of a continuing series of lots, the application of switching rules helps to ensure that the process average in that series of lots is kept below the specified AQL. Limiting quality does not have the same direct relationship with the process average. This Part of GB/T 2828 is initially designed for the inspection of nonconforming items, which may also be used for the inspection of nonconformities per 100 items unless LQ values are overlarge. If this Part of GB/T 2828 does not apply, the consumers shall refer to the special procedures for limiting quality protection specified in 12.6.2 of GB/T 2828.1. Alternative procedures are provided in this Part of GB/T 2828 to cater for two situations often met in practice: a) Procedure A Procedure A is to be used when the producer and consumer both wish to regard the lot in isolation. In other words, the uniqueness of lot lies in manufacturing only one lot according to its type. b) Procedure B Procedure B is to be used when the producer regards the lot as one of continuing series but the consumer considers the lot received in isolation. In other words, the consumers only receive one lot (or few lots) in the continuous series of lots. Procedure B is stated in Appendix A. 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this Part of GB/T 2828. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document referred to applies. GB/T 2828.1-2003 Sampling procedures for inspection by attributea-Part1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection (ISO 2859-1:1999, IDT) ISO 3534-1:2006 Statistics-Vocabulary and symbols-Part 1: General statistical terms and terms used in probability ISO 3534-2:2006 Statistics-Vocabulary and symbols-Part 2: Applied statistics 3 Terms, Definitions and Symbols 3.1 Terms and Definitions The following terms and definitions are applicable to this Part. 3.1.1 Limiting quality Sampling inspection for the isolated lot must be restricted to the quality level of low acceptance probability for the purpose of sampling inspection acceptance.
