Codes & Standards - Purchase
In contrast to the procedures in the other parts of the ISO 2859 series, the procedures in this document are not applicable to acceptance assessment of lots. Generally, this document mainly focuses on controlling type I error, which differs from the balancing of the risks in the procedures for acceptance sampling.
This document can 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 in this document are applicable, but not limited, to the inspection of a variety of targets such as:
— end items;
— components and raw materials;
— materials in process;
— supplies in storage;
— maintenance operations;
— data or records;
— administrative procedures;
— accounting procedures or accounting entries;
— internal control procedures.
This document considers two types of quality models for discrete items and populations, as follows.
i) The conforming-nonconforming model, where each item is classified as conforming or nonconforming, and where the quality indicator of a population of items is the proportion p of nonconforming items, or, equivalently, the percentage 100 p of nonconforming items.
ii) The nonconformities model, where the number of nonconformities is counted on each item, and where the quality indicator of a population of items is the average number ? of nonconformities found on items in the population, or, equivalently, the percentage 100 ? of nonconformities on items in the population.