INTERNATIONAL STANDARD ISO 3951 1 Sampling Procedures For ....pdf
ISO 3951-1:2013 specifies an acceptance sampling system of single sampling plans for inspection by variables. It is indexed in terms of the acceptance quality limit (AQL) and is designed for users who have simple requirements. (A more comprehensive and technical treatment is given in ISO 3951-2.) ISO 3951-1:2013 is complementary to ISO 2859-1.
INTERNATIONAL STANDARD ISO 3951 1 Sampling procedures for ....pdf
To be specific, ISO 3951-1:2022 specifies single sampling plans for lot-by-lot inspection under certain conditions. These are where the inspection procedure is applied to a continuing series of lots of discrete products all supplied by one producer using one production process, and where only a single quality characteristic, x, of these products is taken into consideration, which must be measurable on a continuous scale.
The idea is that the standard is applied to a single quality characteristic that is measurable on a continuous scale and is normally distributed. For two or more such quality characteristics, see the next standard in the series, BS ISO 3951-2. Note that the procedures in Part 1 are not suitable for lots that have been screened for nonconforming items.
This is achieved using the switching rules that tighten or discontinue sampling inspection when a deterioration in quality is detected; and conversely, and at the discretion of the responsible authority, switches to a smaller sample size (reducing inspection costs) if consistently good quality is achieved. ISO 3951-1:2022 thus enables users to improve sampling efficiency and reduce risk simultaneously.
ISO 3951-1:2022 is an update to the 2013 version of this standard. The two key changes are that procedures have been introduced to accommodate measurement uncertainty and many of the sampling plans have been adjusted to improve the match between their operating characteristic curves and the operating characteristic curves of the corresponding plans for single sampling by attributes in BS ISO 2859-1.
ISO 3951-1:2005 specifies an acceptance sampling system of single sampling plans for inspection by variables, in which 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.