ISO 18414:2006 specifies a system of single sampling schemes for lot-by-lot inspection by attributes. All the sampling plans of the system are of accept-zero form, i.e. no lot is accepted if the sample from it contains one or more nonconforming items. The schemes depend on a suitably-defined average outgoing quality limit (AOQL), the value of which is chosen by the user; no restrictions are placed on the choice of the value of the AOQL or on the sizes of successive lots in the series. The methodology ensures that the overall average quality reaching the customer or market-place will not exceed the AOQL in the long run.
ISO 18414:2006 is designed for use under the following conditions: 1) where the inspection procedure is to be applied to a series of lots of discrete items that are intended to be identical, and which are all supplied by one producer using one production process; 2) where one or more quality characteristics of these products are taken into consideration, which must all be classifiable as either conforming or nonconforming; 3) where the inspection error involved in classifying the state of a product's quality characteristic(s) is negligible; and 4) where inspection is non-destructive.
ISO 18414:2006 can be suitable for regulatory purposes, as control of the expected quality of items reaching the market-place is achieved with the smallest possible sample sizes, and long-term control of the realized, or actual quality level in the market-place is achieved with certainty, regardless of how long or short individual suppliers' series may be. ISO 18414:2006 can be used by suppliers/producers, buyers/consumers and regulatory agencies to provide control of the expected quality of the totality of accepted product of each type from each source.