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4 Expression of nonconformity
4.1 General
4.2 Classification of nonconformities
5 Acceptance quality limit (AQL)
5.1 Use and application
5.2 Specifying AQLs
5.3 Preferred AQLs
6 Submission of product for sampling
6.1 Formation of lots
6.2 Presentation of lots
7 Acceptance and non-acceptance
7.1 Acceptability of lots
7.2 Disposition of non-acceptable lots
7.3 Nonconforming items
7.4 Classes of nonconformities or nonconforming items
7.5 Special reservation for critical classes of nonconformities
7.6 Resubmitted lots
8 Drawing of samples
8.1 Sample selection
8.1.1 General
8.1.2 Skip-lot
8.2 When to draw the samples
8.3 Double or multiple sampling
9 Normal, tightened, reduced and skip-lot sampling inspection
9.1 Start of inspection
9.2 Continuation of inspection
9.3 Switching rules and procedures
9.3.1 Normal to tightened
9.3.2 Tightened to normal
9.3.3 Normal to reduced
9.3.4 Reduced to normal
9.3.5 Skip-lot to normal
9.3.6 Reduced to skip-lot
9.4 Discontinuation of inspection
9.5 Skip-lot sampling inspection
9.5.1 General requirements
9.5.2 Producer and product qualification
9.5.3 Qualification and disqualification
9.5.4 Responsibilities on producer qualification
10 Sampling plans
10.1 Inspection level
10.2 Sample size code letters
10.3 Obtaining a sampling plan
10.4 Types of sampling plans
11 Determination of acceptability
11.1 Inspection for nonconforming items
11.2 Single sampling plans (integer acceptance number)
11.3 Double sampling plans
11.4 Multiple sampling plans
11.5 Inspection for nonconformities
12 Further information
12.1 Operating characteristic (OC) curves
12.2 Process average
12.3 Average outgoing quality (AOQ)
12.4 Average outgoing quality limit (AOQL)
12.5 Average sample size curves
12.6 Consumer's and producer's risks
12.6.1 Use of individual plans
12.6.2 Consumer's risk quality (CRQ) tables
12.6.3 Producer's risk (PR) tables
13 Fractional acceptance number plans for single sampling (optional)
13.1 Application of fractional acceptance number plans
13.2 Acceptability determination
13.2.1 Inspection for nonconforming items
13.2.2 Inspection for number of nonconformities
13.3 Switching rules
13.3.1 Normal to tightened and tightened to normal
13.3.2 Normal to reduced
13.3.3 Reduced to normal inspection and discontinuation of inspection
13.3.4 Non-constant sampling plan
14 Inspection errors
15 Sample size code letters
16 Tables of single sampling plans
17 Tables of double sampling plans
18 Tables of multiple sampling plans
19 Tables of producer’s risk (PR)
20 Tables of consumer risk quality (CRQ)
21 Tables of average outgoing quality limits (AOQL)
22 Average sample size comparisons by acceptance number
23 Tables of single sampling fractional acceptance number plans
24 Normalized scheme operating characteristic curves
Annex A (informative) Example for non-constant sampling plan
Annex B (informative) Sampling strategies
Annex C (normative) Procedures for random selection at the skip-lot sampling inspection frequency
Annex D (informative) Skip-lot sampling inspection
Annex E (informative) The construction of operating characteristic (OC) and average sample number (ASN) curves
Annex F (informative) Construction of sampling plans
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International Standard ISO 2859-1 | |
Sampling procedures for inspection by attributes Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection Règles d’échantillonnage pour les contrôles par attributs — Partie 1: Procédures d’échantillonnage pour les contrôles lot par lot, indexés d’après le niveau de qualité acceptable (NQA) Reference number ISO 2859-1:2026(en) | Third edition 2026-01
© ISO 2026
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COPYRIGHT PROTECTED DOCUMENT
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of the requester.
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ContentsPage
4 Expression of nonconformity
4.1 General
4.2 Classification of nonconformities
5 Acceptance quality limit (AQL)
5.1 Use and application
5.2 Specifying AQLs
5.3 Preferred AQLs
6 Submission of product for sampling
6.1 Formation of lots
6.2 Presentation of lots
7 Acceptance and non-acceptance
7.1 Acceptability of lots
7.2 Disposition of non-acceptable lots
7.3 Nonconforming items
7.4 Classes of nonconformities or nonconforming items
7.5 Special reservation for critical classes of nonconformities
7.6 Resubmitted lots
8 Drawing of samples
8.1 Sample selection
8.1.1 General
8.1.2 Skip-lot
8.2 When to draw the samples
8.3 Double or multiple sampling
9 Normal, tightened, reduced and skip-lot sampling inspection
9.1 Start of inspection
9.2 Continuation of inspection
9.3 Switching rules and procedures
9.3.1 Normal to tightened
9.3.2 Tightened to normal
9.3.3 Normal to reduced
9.3.4 Reduced to normal
9.3.5 Skip-lot to normal
9.3.6 Reduced to skip-lot
9.4 Discontinuation of inspection
9.5 Skip-lot sampling inspection
9.5.1 General requirements
9.5.2 Producer and product qualification
9.5.3 Qualification and disqualification
9.5.4 Responsibilities on producer qualification
10 Sampling plans
10.1 Inspection level
10.2 Sample size code letters
10.3 Obtaining a sampling plan
10.4 Types of sampling plans
11 Determination of acceptability
11.1 Inspection for nonconforming items
11.2 Single sampling plans (integer acceptance number)
11.3 Double sampling plans
11.4 Multiple sampling plans
11.5 Inspection for nonconformities
12 Further information
12.1 Operating characteristic (OC) curves
12.2 Process average
12.3 Average outgoing quality (AOQ)
12.4 Average outgoing quality limit (AOQL)
12.5 Average sample size curves
12.6 Consumer's and producer's risks
12.6.1 Use of individual plans
12.6.2 Consumer's risk quality (CRQ) tables
12.6.3 Producer's risk (PR) tables
13 Fractional acceptance number plans for single sampling (optional)
13.1 Application of fractional acceptance number plans
13.2 Acceptability determination
13.2.1 Inspection for nonconforming items
13.2.2 Inspection for number of nonconformities
13.3 Switching rules
13.3.1 Normal to tightened and tightened to normal
13.3.2 Normal to reduced
13.3.3 Reduced to normal inspection and discontinuation of inspection
13.3.4 Non-constant sampling plan
14 Inspection errors
15 Sample size code letters
16 Tables of single sampling plans
17 Tables of double sampling plans
18 Tables of multiple sampling plans
19 Tables of producer’s risk (PR)
20 Tables of consumer risk quality (CRQ)
21 Tables of average outgoing quality limits (AOQL)
22 Average sample size comparisons by acceptance number
23 Tables of single sampling fractional acceptance number plans
24 Normalized scheme operating characteristic curves
Annex A (informative) Example for non-constant sampling plan
Annex B (informative) Sampling strategies
Annex C (normative) Procedures for random selection at the skip-lot sampling inspection frequency
Annex D (informative) Skip-lot sampling inspection
Annex E (informative) The construction of operating characteristic (OC) and average sample number (ASN) curves
Annex F (informative) Construction of sampling plans
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC 5, Acceptance sampling.
This third edition cancels and replaces the second edition (ISO 2859-1:1999), which has been technically revised. It also incorporates ISO 2859-1:1999/Amd.1:2011 and ISO 2859-1:1999/Cor.1:2001.
The main changes are as follows:
—
a new procedure for switching from normal (or reduced inspection) to skip-lot sampling inspection has been added;
—
guidance on the requirements for producer and product qualification for skip-lot sampling inspection has been added;
—
guidance on the efficacy of implementing skip-lot sampling inspection and some methods of randomly selecting lots to inspect or skip has been added;
—
the operating characteristic (OC) curves for each plan have been removed in favour of sharing methods to create an individual plan's OC curve and average sample number (ASN) curve, both of which are now included in Annex E.
It is highly recommended that this document be used together with ISO 2859-0:1995, which contains illustrative examples.
A list of all parts in the ISO 2859 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.
Introduction
The objectives of the methods laid down in this document 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 control the change from the initial normal inspection to tightened or reduced inspection and which provide the following:
a)
An automatic protection to the consumer (by means of a switch to tightened inspection or discontinuation of sampling inspection) if a deterioration in quality (i.e. an increase in nonconformities) be detected.
b)
An incentive (at the discretion of the responsible authority) to reduce inspection costs (either by means of a switch to a smaller sample size and/or to skip the inspection of randomly chosen lots) if consistently good quality be achieved.
In this document, the acceptance of a lot is implicitly determined from an estimate of the percentage of nonconforming items, or nonconformities per 100 items, in the process, based on a random sample of items from the lot.
This document 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, this document is applied to each one separately.
This document is intended for application to quality characteristics by either counting the number of nonconforming items in the sample (binomial distribution) or counting the number of nonconformities in a sample (Poisson distribution).
The choice of the most suitable attributes plan requires experience, judgement, and some knowledge of both statistics and the product to be inspected. Clause 5 of this document is intended to help those responsible for specifying sampling plans in making this choice.
The basic definitions and notations are provided in Clause 3 and Clause 4. The operational rules are contained in Clause 5 through Clause 11. Clause 12 provides further information on the monitoring of inspection results and the underlying process. Clause 13 provides information on the application of fractional acceptance number plans. The purpose of these plans is to provide a consistent progression from plans with acceptance number zero and plans with acceptance number one. All the tables needed for the sampling procedures can be found in Clause 15.
Six annexes are provided. Annex A is for information only and illustrates an example where the sampling plan applied is non-constant. Annex B shows five different sampling strategies. Annex C specifies the procedures for random selection at the skip-lot frequency. Annex D provides a comparison between skip-lot and continuous sampling inspection in terms of average number of inspections, the producer’s and the consumer’s risks. Annex E details the construction of the operating characteristic (OC) and average sample number curves. Annex F specifies the principles and methodology for constructing attribute sampling plans.
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1Scope
This document specifies an acceptance sampling system of single, double, and multiple sampling plans for inspection by attributes. This document specifies sampling schemes indexed by acceptance quality limit (AQL) for inspection by attributes.
Its purpose is to incentivize the producer through the economic and psychological pressure of lot non-acceptance to maintain a process average at least as good as the specified acceptance quality limit, while at the same time providing an upper limit for the risk to the consumer of accepting the occasional poor lot.
Sampling schemes designated in this document are applicable, but not limited, to inspection of
—
items, such as complete products, sub-assemblies or individual components,
—
operations,
—
materials in process,
—
supplies in storage,
—
maintenance operations,
—
data or records, and
—
administrative procedures.
1.1Continuous inspection
These schemes are intended to be used for a continuing series of lots, that is, a series long enough to allow the switching rules (9.3) to be applied. These rules provide:
a)
a protection to the consumer (by means of a switch to tightened inspection or discontinuation of sampling inspection) if a deterioration in quality be detected.
b)
an incentive (at the discretion of the responsible authority) to reduce inspection costs (by means of a switch to reduced inspection or the adoption of skip-lot sampling inspection (see 1.2)) if consistently good quality be achieved.
1.2Skip-lot inspection
This document also specifies optional skip-lot sampling inspection procedures (see 9.5) for acceptance inspection by attributes. The purpose of these procedures is to provide a way of reducing the inspection effort on products of high quality submitted by a producer who has a satisfactory quality assurance system and effective quality controls. The reduction in inspection effort is achieved by determining at random, with a specified probability, whether a lot presented for inspection will be accepted without inspection. This procedure extends the principle of the random selection of sample items already applied in this document to the random selection of lots. The skip-lot sampling inspection procedures specified in this document are applicable to, but not limited to, inspection of the items detailed in 1.1.
2Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in probability
ISO 3534-2, Statistics — Vocabulary and symbols — Part 2: Applied statistics
ISO 24153, Random sampling and randomization procedures
3Terms, definitions and symbols
3.1Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3534-1 and ISO 3534-2, and the following apply.
NOTEFor ease of reference, the definitions of some of these terms are quoted from ISO 3534-1 and ISO 3534-2, while others are redefined or newly defined.
3.1.1
acceptance quality limit
AQL
worst tolerable quality level (3.1.29)
Note 1 to entry: This concept only applies when a sampling scheme with rules for switching and for discontinuation, such as in ISO 2859-1 or ISO 3951, is used.
Note 2 to entry: Although individual lots with quality as bad as the acceptance quality limit may be accepted with fairly high probability, the designation of an acceptance quality limit does not suggest that this is a desirable quality level.
Note 3 to entry: Sampling schemes found in International Standards such as this part of ISO 2859 with their rules for switching and for discontinuation of sampling inspection, are designed to encourage producers to have process averages consistently better than the AQL. If producers fail to do so, there is a high probability of being switched from normal inspection to tightened inspection where lot acceptance becomes more difficult. Once on tightened inspection, unless action is taken to improve the process, it is very likely that the rule requiring discontinuation of sampling inspection pending such improvement will be invoked.
[SOURCE: ISO 3534-2:2006, 4.6.15, modified — Original Note 4 to entry removed.]
3.1.2
acceptance score
indicator that is used for fractional acceptance number plans to determine lot acceptability
Note 1 to entry: See 13.2.1.2.
3.1.3
average outgoing quality
AOQ
expected average quality level (3.1.29) of outgoing product for a given value of incoming product quality
Note 1 to entry: Unless otherwise specified, the average outgoing quality is calculated over all accepted lots plus all non-accepted lots after the latter have been inspected 100 % and the nonconforming items replaced by conforming items.
Note 2 to entry: The approximation used here is: “Average outgoing quality = incoming process quality × probability of acceptance”. This formula is exact for accept-zero plans and overestimates otherwise.
[SOURCE: ISO 3534-2:2006, 4.7.1, modified — The original Note 2 to entry removed and Note 3 renumbered.]
3.1.4
average outgoing quality limit
AOQL
maximum value that AOQ (3.1.3) can be, over all possible values of incoming product quality which might be submitted, for a given acceptance sampling plan, and with rectification of all non-accepted lots unless specified otherwise
Note 1 to entry: It represents the maximum long run percentage nonconforming that the consumer can see under these circumstances.
[SOURCE: ISO 3534-2:2006, 4.7.2, modified — Maximum long run percentage added.]
3.1.5
average sample number
ASN
average number of units in sample (3.1.32) inspected per lot (3.1.15) in reaching decisions to accept or not to accept when using a given acceptance sampling plan (3.1.34)
Note 1 to entry: ASN is dependent on the actual quality level of the submitted lots.
[SOURCE: ISO 3534-2:2006, 4.7.3, modified — Average sample number (ASN) is the preferred term and equivalent to the admitted term average sample size (ASSI) in the source.]
3.1.6
consumer
user or buyer as appropriate
Note 1 to entry: The consumer and the producer may even be different departments of the same company.
Note 2 to entry: See also producer (3.1.26).
3.1.7
3.1.8
defect
non-fulfilment of a requirement related to an intended or specified use
Note 1 to entry: The distinction between the concepts defect and nonconformity (3.1.20) is important as it has legal connotations, particularly those associated with product liability issues. Consequently, the term “defect” should be used with extreme caution.
[SOURCE: ISO 3534-2:2006, 3.1.12, modified — Note 2 to entry removed.]
3.1.9
disqualification
failure to qualify for skip-lot sampling inspection (3.1.37)
3.1.10
inspection
activity such as measuring, examining, testing, or gauging one or more characteristics of a product or service, and comparing the results with specified requirements in order to establish whether conformity is achieved for each characteristic
[SOURCE: ISO 3534-2:2006, 4.1.2, modified — "judgement" has been changed to "comparing results with required specification". The definition here includes the notion of establishing conformity on one or more characteristics.]
3.1.11
inspection by attributes
inspection whereby the presence or absence of one or more specified characteristics of each item in a sample (3.1.32) is observed to establish statistically the acceptability of a lot (3.1.15) or process
Note 1 to entry: Inspection by attributes includes inspection for conformity of items as well as inspection for number of nonconformities per hundred items.
[SOURCE: ISO 3534-2:2006, 4.2.12, acceptance sampling by attributes, modified — Term, note 1 to entry added.]
3.1.12
interruption
cessation of skip-lot sampling inspection (3.1.37) ending with a return to continuous inspection
3.1.13
item
anything that can be described and considered separately
Note 1 to entry: EXAMPLE
—
a physical item;
—
a defined amount of bulk material;
—
a service, activity or process;
—
an organization, system, person;
—
some combination thereof.
Note 2 to entry: Object is a deprecated term.
[SOURCE: ISO 3534-2:2006, 1.2.11, modified — "process" and "organisation" added. Note 1 to entry removed and Note 2 renumbered.]
3.1.14
limiting quality
LQ
quality level (3.1.29) which is the limit of an unsatisfactory process average when a continuing series of lots is considered
Note 1 to entry: when a lot is considered in isolation, a quality level which for the purposes of sampling inspection has a low probability of acceptance
Note 2 to entry: See also consumer’s risk quality, CRQ (3.1.7)
[SOURCE: ISO 3534-2:2006, 4.6.14, limiting quality level, modified — Term, notes 1 and 2 to entry added.]
3.1.15
lot
definite amount of some product, material or service, constituted under essentially the same conditions, and collected together
Note 1 to entry: This definition differs from that in ISO 3534-2:2006, 1.2.4.
Note 2 to entry: An inspection lot may consist of several batches or parts of batches.
3.1.16
lot size
number of items in a lot
3.1.17
3.1.18
nonconformities per 100 items in a sample
one hundred times the number of nonconformities (3.1.20) in the sample divided by the sample size, viz:
mml_m1  |
where | ||||
|---|---|---|---|---|
|
3.1.19
nonconformities per 100 items in a population or lot
one hundred times the number of nonconformities (3.1.20) in the population or lot divided by the population or lot size, viz:
mml_m2  |
where | ||||||
|---|---|---|---|---|---|---|
|
Note 1 to entry: An item may contain one or more nonconformities.
3.1.20
nonconformity
non-fulfilment of a requirement
Note 1 to entry: See notes to defect (3.1.8).
Note 2 to entry: Nonconformity will generally be classified according to its degree of seriousness such as:
—
Class A: those nonconformities of a type considered to be of the highest concern; in acceptance sampling such types of nonconformities will be assigned a very small acceptance quality limit value.
—
Class B: those nonconformities of a type considered to have the next lower degree of concern; therefore, these can be assigned a larger acceptance quality limit value than those in class A and smaller than in class C, if a third class exists, etc.
Note 3 to entry: Adding characteristics and classes of nonconformities will generally affect the overall probability of acceptance of the product.
Note 4 to entry: The number of classes, the assignment into a class, and the choice of acceptance quality limit for each class, shall be appropriate to the quality requirements of the specific situation.
[SOURCE: ISO 3534-2:2006, 3.1.11, modified — Notes 2, 3, and 4 added.]
3.1.21
normal inspection
inspection level which is used when there is no reason to suspect that the process average (3.1.25) differs from an acceptable level.
Note 1 to entry: inspection using a sampling plan (3.1.34) with an acceptance criterion that has been devised to secure the producer a high probability of acceptance when the process average (3.1.25) of the lot is better than the acceptance quality limit (3.1.1).
Note 2 to entry: This definition differs from that in ISO 3534-2:2006, 4.1.10.
3.1.22
original inspection
Note 1 to entry: This is in contrast, for example, to inspection of a lot which has previously been designated as not acceptable and which is submitted again for inspection after having been further sorted, reprocessed, etc.
[SOURCE: ISO 3534-2:2006, 4.1.16]
3.1.23
percent non -conforming in a sample
one hundred times the number of nonconforming items (3.1.17) in the sample divided by the sample size, viz:
mml_m3  |
where | ||||
|---|---|---|---|---|
|
3.1.24
percent nonconforming in a population or lot
one hundred times the number of nonconforming items (3.1.17) in the population or lot divided by the population or lot size, viz:
mml_m4  |
where | ||||||
|---|---|---|---|---|---|---|
|
Note 1 to entry: In this document the terms percent nonconforming (3.1.23) in a sample and percent nonconforming (3.1.23) in a population or lot or nonconformities per 100 items in a sample (3.1.18) and nonconformities per 100 items in a population or lot (3.1.19) are mainly used in place of the theoretical terms "proportion of nonconforming items" and "nonconformities per item" because the former terms are the most widely used.
3.1.25
process average
quality level (3.1.29) during a period when the process is in a state of statistical control
3.1.26
producer
seller, supplier, vendor, manufacturer or producer as appropriate for the situation
Note 1 to entry: The producer and the consumer may even be different departments in the same company.
Note 2 to entry: The producer is important in this part of the ISO 2859 standard as it depends on the operation of the switching rules in response to changes in quality level. Only the producer is in a position to do this. Although Sellers and vendors may also change quality through screening lots from the manufacturer.
Note 3 to entry: See also consumer (3.1.6).
3.1.27
producer’s risk
PR
probability of nonacceptance when the quality level (3.1.29) has a value stated by the plan as acceptable
Note 1 to entry: Quality level could relate to fraction nonconforming and be acceptable to AQL.
Note 2 to entry: Interpretation of the producer’s risk requires knowledge of the stated quality level.
[SOURCE: ISO 3534-2:2006, 4.6.4.]
3.1.28
product qualification
assessment of the product to determine its suitability for skip-lot sampling inspection (3.1.37)
3.1.29
quality level
quality expressed as a percentage of nonconforming items (3.1.24) or number of nonconformities per 100 items in the lot (3.1.19)
[SOURCE: ISO 3534-2:2006, 4.6.16, modified — for nonconforming items, rate is replaced with percentage and for nonconformities, rate of , is deleted and, per 100 items, added.]
3.1.30
reduced inspection
inspection less severe than normal inspection (3.1.21) to which the latter is switched when inspection results of a predetermined number of lots indicate that the quality level (3.1.29) achieved by the process is better than that specified
Note 1 to entry: Reduced inspection may be invoked when the inspection results of a predetermined number of consecutive lots indicate that the process average (3.1.25)is better than the AQL (3.1.1).
[SOURCE: ISO 3534-2:2006, 4.1.11, modified — Notes 1 to entry added.]
3.1.31
responsible authority
person(s) or organization who has the responsibility and authority to manage implementation of sampling procedures as per this document.
Note 1 to entry: The responsible authority may be
Note 2 to entry: this term is used to maintain the neutrality of this document (primarily for specification purposes), irrespective of which party is invoking or applying it.
Note 3 to entry: The duties and functions of a responsible authority are outlined in this document (see 5.2, 6.2, 7.2, 7.3, 7.5, 7.6, 9.1, 9.3.3, 9.4, 9.5, 10.1, 10.3, 13.1).
3.1.32
sample
set of one or more items taken from a lot and intended to provide information on the lot
Note 1 to entry: This definition differs from that in ISO 3534-2:2006, 1.2.17.
3.1.33
sample size
number of items in the sample
Note 1 to entry: This definition differs from that in ISO 3534-2:2006, 1.2.26.
3.1.34
sampling plan
plan which states the sample size(s) to be used and the associated criteria for lot acceptance
Note 1 to entry: A single sampling plan is a combination of sample size and acceptance and rejection numbers. Double and multiple sampling plans are a combination of two or more sample sizes and associated acceptance and rejection numbers for the first sample and for subsequent combined samples.
Note 2 to entry: A sampling plan does not contain the rules on how to draw the sample.
Note 3 to entry: For the purposes of this document, a distinction should be made between the terms sampling plan (3.1.34) sampling scheme (3.1.35) and sampling system (3.1.36).
[SOURCE: ISO 3534-2:2006, 4.3.3, acceptance sampling plan, modified — Term, notes 1, 2 and 3 to entry added.]
3.1.35
sampling scheme
combination of sampling plans with switching rules for changing from one plan to another
Note 1 to entry: See 9.3.
[SOURCE: ISO 3534-2:2006, 4.3.2. acceptance sampling scheme, modified — Term.]
3.1.36
sampling system
collection of sampling plans, or of sampling schemes, each with its own rules for changing plans, together with sampling procedures including criteria by which appropriate plans or schemes may be chosen
Note 1 to entry: This document is a sampling system indexed by lot-size ranges, inspection levels and AQLs. A sampling system for LQ plans is given in ISO 2859-2.
Note 2 to entry: This definition differs from that in ISO 3534-2:2006, 5.4.1.
3.1.37
skip-lot sampling inspection
inspection in which some lots in a series are accepted without inspection, when the sampling results for 10 immediately preceding lots meet the stated criteria
Note 1 to entry: The lots to be inspected are chosen randomly in accordance with the skip-lot inspection frequency of 2 in 5.
[SOURCE: ISO 3534-2:2006, 4.2.5, modified — "a stated number of" changed to 10 and Note 1 to entry added.]
3.1.38
3.1.39
3.2Symbols and abbreviations
The symbols and abbreviations used in this document are as follows:
| Ac | acceptance number |
| AQL | acceptance quality limit |
| AOQ | average outgoing quality |
| AOQL | average outgoing quality limit |
| CRQ | consumer's risk quality |
| d | number of nonconforming items (or nonconformities) found in a sample from a lot |
| D | number of nonconforming items in a lot |
| LQ | limiting quality |
| N | lot size |
| n | sample size |
| p | process average |
| px | quality level for which the probability of acceptance is x, where x is a fraction |
| Pa | probability of acceptance |
| Re | rejection number |
NOTEThe symbol n may be accompanied by a subscript. Numerical subscripts 1 or 2 denote the first or second sample, respectively. In general, ni is the size of the ith sample in double or multiple sampling.
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Bibliography
[1] | ISO 3951 (all parts), Sampling procedures and charts for inspection by variables | |
[2] | ISO 8402, Quality management and quality assurance — Vocabulary | |
[3] | ISO 2859-0, Sampling procedures for inspection by attributes — Part 0: Introduction to the ISO 2859 attribute sampling system | |
[4] | ISO 2859-2, Sampling procedures for inspection by attributes — Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection | |
[5] | AIAG (2010). Measurement System Analysis, MSA (4th ed.). Automotive Industry Action Group. ISBN 978-1-60-534211-5 | |
[6] | Schilling, E. G., & Neubauer, D. V. (2009). Acceptance sampling in quality control. Chapman and Hall/CRC. | |
[7] | COCHRAN, W.G. (2007) - Sampling Techniques. 3rd Edition, Wiley - New York |
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ICS 03.120.30 Price based on 82 pages
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