BS ISO 3951-4:2011 BS 6002-5 BSl Standards Publication Sampling procedures for inspection by variables Part 4: Procedures for assessment of declared quality levels bsi. ..making excellence a habit: BS ISO 3951-4:2011 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 3951-4:2011. The UK participation in its preparation was entrusted to Technical Committee Ss/5, Acceptance sampling schemes. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. @BSI 2011 ISBN9780580661426 ICS 03.120.30 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2011. Amendments issued since publication Date Text affected BS ISO 3951-4:2011 INTERNATIONAL ISO STANDARD 3951-4 First edition 2011-08-15 Sampling procedures for inspection by variables Part 4: Procedures for assessment of declared quality levels Reglesd'echantllonnagepourles controles parmesures Partie 4:Procedures pourI'évaluation des niveaux declares de qualite Referencenumber ISO 3951-4:2011(E) ISO @ISO2011 BS ISO 3951-4:2011 ISO 3951-4:2011(E) COPYRIGHTPROTECTEDDOCUMENT ISO 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, ISO copyright office Casepostale56.CH-1211Geneva20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland ii @ ISO 2011 - All rights reserved BS ISO 3951-4:2011 ISO 3951-4:2011(E) Contents Page Foreword iv Introduction 1 Scope 2 Normative references.. 2 3 Terms,definitions,symbolsandabbreviations. 2 4 Principles.... 5 Declared quality level (DQL)... 6 Samplingplans. 5 7 Operatingasamplingplan.. 8 8 Further information. ..15 AnnexA(informative)Method of matchingvariablesplansto attributes plans 20 AnnexB (informative)Examples ofuse oftheprocedures. 21 Bibliography.... @ ISO 2011 - All rights reserved ili BS ISO3951-4:2011 ISO 3951-4:2011(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2 The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for identifying any or all such patent rights. ISO3951-4 wasprepared by Technical CommitteeISO/TC69,Application of statistical methods, SubcommitteeSC5,Acceptancesampling. Iso 3951 consists of the following parts, under the general title Sampling procedures for inspection by variables: inspectionforasinglequalitycharacteristicandasingleAQL lot-by-lot inspectionof independentqualitycharacteristics Part4:Proceduresforassessmentofdeclaredqualitylevels (knownstandarddeviation) iv ISO 2011 - All rights reserved BSISO3951-4:2011 ISO 3951-4:2011(E) Introduction 5.TheacceptancesamplingproceduresthatarespecifiedinIsO3951Parts1,2,3and5areintendedtobe used in bilateral agreements between two parties.Those acceptance sampling procedures are intended to be used as simple, pragmatic rules for releasing product after inspection of only a limited sample of a formallydeclared qualitylevel. acceptable and qualities that should be rejected by the procedure. For the procedures in IsO 3951 Pa