Sampling procedures for inspection by attributes — Part 5: System of sequential sampling plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection

ISO 2859-5:2005 contains sequential sampling schemes that supplement the ISO 2859-1 acceptance sampling system for inspection by attributes, whereby a supplier, through the economic and psychological pressure of lot non-acceptance, can maintain a process average at least as good as the specified acceptance quality limit, while at the same time provide an upper limit for the risk to the consumer of accepting the occasional poor lot.

The sampling schemes defined in ISO 2859-5:2005 are applicable, but not limited, to the inspection of: end items, components and raw materials, operations, materials in process, supplies in storage, maintenance operations, data or records, and administrative procedures.

These schemes are designed to be applied to a continuing series of lots, that is, a series long enough to permit the described switching rules to be applied. These switching rules provide: a) enhanced protection to the consumer (by means of tightened sampling inspection criteria or discontinuation of sampling inspection) should deterioration in quality occur; and b) an incentive, at the discretion of the responsible authority, to reduce inspection costs (by means of reduced sampling ins