1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-21182-0 SANS 2859-4:2008 Edition 1 ISO 2859-4:2002 Edition 2SOUTH AFRICAN NATIONAL STANDARD Sampling procedures for inspection by attribut
4、es Part 4: Procedures for assessment of declared quality levels This national standard is the identical implementation of ISO 2859-4:2002 and is adopted with the permission of the International Organization for Standardization. Published by Standards South Africa 1 dr lategan road groenkloof private
5、 bag x191 pretoria 0001 tel: 012 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa This standard may only be used and printed by approved subscription and freemailing clients of the SABS.SANS 2859-4:2008 Edition 1 ISO 2859-4:2002 Edition 2 Table of changes
6、 Change No. Date Scope National foreword This South African standard was approved by National Committee StanSA TC 169, Applications of statistical methods, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published i
7、n April 2008. This standard may only be used and printed by approved subscription and freemailing clients of the SABS.INTERNATIONAL STANDARD ISO 2859-4 Second edition 2002-08-01 Reference number ISO 2859-4:2002(E) ISO 2002 Sampling procedures for inspection by attributes Part 4: Procedures for asses
8、sment of declared quality levels Rgles dchantillonnage pour les contrles par attributs Partie 4: Procdures pour lvaluation des niveaux dclars de qualitSANS 2859-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO 2859-4:2002(E) ii ISO 200
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12、ss given below. ISO 2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs
13、member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland SANS 2859-4:2008This standard may only be used and printed by approved subscription and freema
14、iling clients of the SABS.ISO 2859-4:2002(E) ISO 2002 All rights reserved iii Contents Page 1 Scope . 1 2 Normative references . 2 3 Terms, definitions, symbols and abbreviations . 2 4 Principles 3 5 Declared quality level (DQL) . 4 6 Sampling plans . 4 7 Operating a sampling plan 6 8 Further inform
15、ation . 7 Annex A Examples of use of the procedures 11 A.1 Example 1 . 11 A.2 Example 2 . 11 A.3 Example 3 . 11 SANS 2859-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO 2859-4:2002(E) iv ISO 2002 All rights reserved Foreword ISO (the
16、 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 committe
17、e 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 electrotechni
18、cal standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval
19、by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of ISO 2859 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 2859-4 was p
20、repared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC 5, Acceptance sampling. This second edition cancels and replaces the first edition (ISO 2859-4:1999), which has been technically revised. ISO 2859 consists of the following parts, under the general title S
21、ampling procedures for inspection by attributes: Part 0: Introduction to the ISO 2859 attribute sampling system Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection Part 2: Sampling plans indexed by limiting quality (LQ) for isolated lot inspection Part 3: Ski
22、p-lot sampling procedures Part 4: Procedures for assessment of declared quality levels Annex A of this part of ISO 2859 is for information only. SANS 2859-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO 2859-4:2002(E) ISO 2002 All rig
23、hts reserved v Introduction The procedures in this part of ISO 2859 differ in their scope from the procedures in ISO 2859 Parts 1 to 3. The system of acceptance sampling procedures that are specified in ISO 2859 Parts 1 to 3 are intended to be used in bilateral agreements between two parties. The ac
24、ceptance sampling procedures are intended to be used as simple, pragmatic rules for releasing product after inspection of only a limited sample of a consignment, and therefore the procedures do not make reference (either explicitly or implicitly) to any formally declared quality level. Under accepta
25、nce sampling there is no sharp borderline between quality levels that should be considered acceptable and qualities that should be rejected by the procedure. For the procedures in ISO 2859-1 the two parties agree upon some acceptance quality limit (AQL) which is the worst tolerable process average w
26、hen a continuing series of lots is submitted. The switching rules and the sampling schemes in ISO 2859-1 are designed to encourage the suppliers to have process averages consistently better than the AQL selected. In order to keep sample sizes moderate, the protection against accepting individual lot
27、s of inferior quality may be less than that provided by sampling plans targeted for sentencing individual lots. The procedures in ISO 2859-2, on the contrary, are designed to provide good protection against accepting individual lots of inferior quality (LQ), but at the expense of a possible high ris
28、k of not accepting lots of qualities that both parties actually would consider to be acceptable. Procedures in ISO 2859 Parts 1 to 3 are well suited for acceptance sampling purposes, but they should not be used in reviews, audits, etc. to verify a quality that has been declared for some entity. The
29、main reason is that the procedures have been indexed in terms of quality levels that are relevant solely for the pragmatic purposes of acceptance sampling, and the various risks have been balanced accordingly. The procedures in this part of ISO 2859 have been developed as a response to the growing n
30、eed for sampling procedures suitable for formal, systematic inspections such as reviews or audits. When performing such a formal inspection, it is necessary for the authority to consider the risk of reaching an incorrect conclusion, and to take this risk into account in planning and executing the re
31、view/audit/testing, etc. This part of ISO 2859 provides guidance and rules to assist the user in taking this risk into account in an informed manner. The rules in this part of ISO 2859 have been devised such that there is only a small, limited risk of contradicting the declared quality level when in
32、 fact the actual level conforms to the declared level. If it were also desired that there should be a similarly small risk of not contradicting the declared quality level when in fact the actual quality level does not conform to the declared quality level, then it would be necessary to investigate a
33、 rather large sample. Therefore, in order to obtain the benefit of a moderate sample size, the procedures in this part of ISO 2859 have been devised in such a way that they allow a somewhat higher risk of failing to contradict the declared quality level when in fact the actual quality level does not
34、 conform to the declared quality level. The wording of the result of the assessment should reflect this unbalance between the risks of reaching incorrect conclusions. When the sample result contradicts the declared quality level there is strong evidence of nonconformance to the declared quality leve
35、l. When the sample result does not contradict the declared quality level, this should be understood as “we have not, in this limited sample, found strong evidence of nonconformance to the declared quality level”. SANS 2859-4:2008This standard may only be used and printed by approved subscription and
36、 freemailing clients of the SABS.SANS 2859-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.INTERNATIONAL STANDARD ISO 2859-4:2002(E) ISO 2002 All rights reserved 1 Sampling procedures for inspection by attributes Part 4: Procedures for as
37、sessment of declared quality levels 1 Scope This part of ISO 2859 establishes sampling plans and procedures that can be used to assess whether the quality level of an entity (lot, process, etc) conforms to a declared value. The sampling plans have been devised so as to obtain a risk of less than of
38、contradicting a correct declared quality level. The risk is of failing to contradict an incorrect declared quality level which is related to the limiting quality ratio (see clause 4). Sampling plans are provided corresponding to three levels of discriminatory ability. In contrast to the procedures i
39、n the other parts of ISO 2859, the procedures in this part of ISO 2859 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. This
40、part of ISO 2859 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 rando
41、m samples of individual items to be taken from the entity. The sampling plans provided in this part of ISO 2859 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
42、operations; data or records; administrative procedures. The procedures are primarily intended to be used when the quantity of interest is the number or fraction of nonconforming items for which the inspected items are classified as conforming or nonconforming. With minor changes, the procedures may
43、also be used when the quantity of interest is the number of nonconformities or number of nonconformities per item. The necessary changes are: replacement of “number of nonconforming items” by “number of nonconformities”; replacement of “percent nonconforming items” by “nonconformities per 100 items”
44、. In this case the values given in Tables 2 to 7 are only approximations. 5 % 10 % SANS 2859-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO 2859-4:2002(E) 2 ISO 2002 All rights reserved 2 Normative references The following normative
45、documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 2859. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 2859 are encouraged to
46、 investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 3534-1:199
47、3, Statistics Vocabulary and symbols Part 1: Probability and general statistical terms ISO 3534-2:1993, Statistics Vocabulary and symbols Part 2: Statistical quality control ISO 9000:2000, Quality management systems Fundamentals and vocabulary 3 Terms, definitions, symbols and abbreviations 3.1 Term
48、s and definitions For the purposes of this part of ISO 2859, the terms and definitions given in ISO 3534-1, ISO 3534-2 and ISO 9000 and the following apply. 3.1.1 limiting number of nonconforming items largest number of nonconforming items (or nonconformities) found in the sample from the entity und
49、er investigation that does not lead to contradiction of the declared quality level 3.1.2 quality ratio ratio of the actual to the declared quality level of the entity under investigation 3.1.3 limiting quality ratio LQR value of the quality ratio that is limited to a small risk ( in this part of ISO 2859) of failing to contradict an incorrect declared quality level 3.2 Symbols and abbreviated terms The symbols and abbreviated terms used in this part of ISO 2859 are as follows: DQL Declared quality le
