Description

This Standard provides sampling plans and procedures for inspection by variables.

Three methods of determining acceptability are included viz.

• the 's' method,
• the 'o' method, and
• the 'r' method.

Appendices cover basic statistical theory, calculation of the estimated standard deviation and the use of the 'r' range method as an alternative to the 's' method.

It is identical with and has been reproduced from ISO 3951:1989.

Scope

This Standard is identical with and has been reproduced from ISO 3951:1989.

The Standard establishes sampling plans and procedures for inspection by variables. It is complementary to ISO 2859. When specified by the responsible authority, both this Standard and ISO 2859 may be referenced in a product or process specification, contract, inspection instructions, or other documents, and the provisions set forth therein shall govern. The "responsible authority" shall be designated in one of the above documents.

The object of the methods laid down in this Standard is to ensure that lots of an acceptable quality have a high probability of acceptance and that the probability of not accepting inferior lots is as high as possible. In common with ISO 2859. the percentage of nonconforming products in the lots is used to define the quality of these lots and of the production process in question.