DS/ISO 3951-1:2013

Sampling procedures for inspection by variables - Part 1: Specification for single sampling plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection for a single quality characteristic and a single AQL

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This part of ISO 3951 is primarily designed for use under the following conditions:
a) where the inspection procedure is to be applied to a continuing series of lots of discrete
products all
supplied by one producer using one production process;

b) where only a single quality characteristic, x, of these products is taken into consideration,
which must be measurable on a continuous scale;

c) where production is stable (under statistical control) and the quality characteristic, x, is
distributed according to a normal distribution or a close approximation to the normal distribution;

d) where a contract or standard defines a lower specification limit, L, an upper specification
limit, U, or both; an item is qualified as conforming if and only if its measured quality
characteristic, x, satisfies the appropriate one of the following inequalities:

1) x = L (i.e. the lower specification limit is not violated);

2) x = U (i.e. the upper specification limit is not violated);

3) x = L and x = U (i.e. neither the lower nor the upper specification limit is violated).

Inequalities 1) and 2) are called cases with a single specification limit and 3), a case with
double specification limits.

Where double specification limits apply, it is assumed in this part of ISO 3951 that conformance to
both specification limits is equally important to the integrity of the product. In such cases, it
is appropriate to apply a single AQL to the combined percentage of a product outside the two
specification limits. This is referred to as combined control.

Number of pages: 108

Published: 2013-09-26

Date of approval: 2013-09-09

International relationships : ISO 3951-1:2013 IDT

ICS: 03.120.30 - Application of statistical methods

Item number: M257761



  • ISO/TC 69/SC 5

Danish committee


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