In contrast to the procedures in the other parts of ISO 3951, the procedures in ISO 3951-4:2011 are not applicable to acceptance assessment of lots. Generally, the balancing of the risks of reaching incorrect conclusions in assessment procedures will differ from the balancing in the procedures for acceptance sampling.
ISO 3951-4:2011 may 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 are applicable, but not limited, to inspection of a variety of products such as: end items; components and raw materials; operations; materials in process; supplies in storage; maintenance operations; data or records; administrative procedures.
The procedures are intended to be used when the quality characteristics are measurable variables that are independent and normally distributed, and where the quantity of interest is the fraction of items that are nonconforming.