The objectives of the methods laid down in ISO 3951-1:2013 are to ensure that lots of acceptable quality have a high probability of acceptance and that the probability of not accepting inferior lots is as high as practicable. This is achieved by means of the switching rules, which provide the following:
In ISO 3951-1:2013, the acceptability of a lot is implicitly determined from an estimate of the percentage of nonconforming items in the process, based on a random sample of items from the lot.
ISO 3951-1:2013 is intended for application to a continuing series of lots of discrete products all supplied by one producer using one production process. If there are different producers or production processes, ISO 3951-1:2013 is applied to each one separately.
ISO 3951-1:2013 is intended for application to a single quality characteristic that is measurable on a continuous scale. For two or more such quality characteristics, see ISO 3951-2.