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 978-0-626-21179-0 SANS 22514-4:2008 Edition 1 ISO/TR 22514-4:2007 Edition 1SOUTH AFRICAN NATIONAL STANDARD Statistical methods in process management
4、 Capability and performance Part 4: Process capability estimates and performance measures This national standard is the identical implementation of ISO/TR 22514-4:2007 and is adopted with the permission of the International Organization for Standardization. Published by Standards South Africa 1 dr l
5、ategan road groenkloof private 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 22514-4:2008 Edition 1 ISO/TR 2251
6、4-4:2007 Edition 1 Table of changes 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.
7、 This SANS document was published in April 2008. This standard may only be used and printed by approved subscription and freemailing clients of the SABS. Reference number ISO/TR 22514-4:2007(E) ISO 2007TECHNICAL REPORT ISO/TR 22514-4 First edition 2007-12-01 Statistical methods in process management
8、 Capability and performance Part 4: Process capability estimates and performance measures Mthodes statistiques dans la gestion de processus Aptitude et performance Partie 4: Estimations de laptitude de processus et mesures de performance SANS 22514-4:2008This standard may only be used and printed by
9、 approved subscription and freemailing clients of the SABS.ISO/TR 22514-4:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed t
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14、i ISO 2007 All rights reservedSANS 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO/TR 22514-4:2007(E) ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Terms and definitions .1 2.1 Basic terms
15、.1 2.2 Process capability, estimates and indices5 2.3 Process performance, measures and indices 8 3 Symbols and abbreviated terms 10 3.1 Symbols 10 3.2 Abbreviated terms .12 4 Statistical measures used in process capability and performance .13 4.1 General13 4.2 Measures of location .13 4.3 Measures
16、of dispersion.13 4.4 Mean square error (MSE) 13 4.5 Reference limits .13 4.6 Reference interval, also known as process spread .13 4.7 Attributes 13 5 Capability14 5.1 General14 5.2 Process capability .15 5.3 Process location 16 5.4 Process capability indices for measured data .17 5.5 Process capabil
17、ity indices for measured data (non-normal) 19 5.6 Alternative method for describing and calculating process capability estimates .21 5.7 Other capability indices for measured data in other special cases .22 5.8 Assessment of proportion out-of-specification (normal distribution).23 5.9 Attributes 24
18、6 Performance .25 6.1 General25 6.2 Process performance indices for measured data (normal distribution)26 6.3 Process performance indices for measured data (non-normal distribution)27 6.4 Other performance indices for measured data.28 6.5 Assessment of proportion out-of-specification (normal distrib
19、ution).28 6.6 Attributes 28 Annex A (informative) Estimating standard deviations.29 Annex B (informative) Estimating capability and performance measures using Pearson curves Procedure and example 31 Annex C (informative) Distribution identification 39 Annex D (informative) Confidence intervals.44 An
20、nex E (informative) Example of the output from computer software46 Bibliography 48 SANS 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO/TR 22514-4:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organizati
21、on 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 ha
22、s 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. Inte
23、rnational Standards are drafted in accordance with the rules given in the ISO/IEC 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. Publica
24、tion as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for exampl
25、e), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the possibili
26、ty 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. ISO/TR 22514-4 has been prepared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC 4, Applications
27、of statistical methods in process management. ISO 22514 consists of the following parts, under the general title Statistical methods in process management Capability and performance: Part 1: General principles and concepts Part 3: Machine performance studies for measured data on discrete parts Part
28、4: Process capability estimates and performance measures Technical Report In the future, it is planned to revise ISO 21747:2006 (Statistical methods Process performance and capability statistics for measured quality characteristics) as Part 2. NOTE ISO/TR 22514-4 was initially prepared as ISO/DTR 12
29、783. It was renumbered before publication to include it in the ISO 22514 series. SANS 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO/TR 22514-4:2007(E) ISO 2007 All rights reserved v Introduction Many organizations have embarke
30、d upon a continuous improvement strategy. To comply with such a strategy, any organization will need to evaluate the capability and performance of its key processes. The methods described in this part of ISO 22514 are intended to assist any management in this respect. These evaluations need to be co
31、nstantly reviewed by management so that actions compatible with continuous improvement can be taken when required. The content of this part of ISO 22514 has been subject to large shifts of opinion during recent times and this report attempts to reflect the current position. The most fundamental shif
32、t has been to philosophically separate what is named in this document as capability conditions from performance conditions, the primary difference being whether statistical stability has been obtained (capability) or not (performance). This naturally leads onto the two sets of indices that are to be
33、 found in their relevant clauses. It has become necessary to draw a firm distinction between these since it has been observed in industry that companies have been deceived about their true capability position due to inappropriate indices being calculated and published. The progression of this part o
34、f ISO 22514 is from the general condition to the specific and this approach leads to general formulae being presented before their more usual but specific manifestations. There exist numerous references that describe the importance of understanding the processes at work within any organization, be i
35、t a manufacturing process or an information handling process. As organizations compete for sales with each other, it has become increasingly apparent that it is not only the price paid for a product or service that matters so much, but also what costs will be incurred by the purchaser from using suc
36、h a product or service. The objective for any supplier is to continually reduce variability and not to just satisfy specification. Continual improvement leads to reductions in the costs of failure and assists in the drive for survival in an increasingly more competitive world. There will also be sav
37、ings in appraisal costs for as variation is reduced the need to inspect product might disappear or the frequency of sampling might be reduced. Process capability and performance evaluations are necessary to enable organizations to assess the capability and performance of their suppliers. Those organ
38、izations will find the indices contained within this part of ISO 22514 useful in this endeavour. Quantifying the variation present within a process enables judgement of its suitability and ability to meet some given requirement. The following paragraphs and clauses provide an outline of the philosop
39、hy required to be understood to determine the capability or performance of any process. All processes will be subject to certain inherent variability. This part of ISO 22514 does not attempt to explain what is meant by inherent variation, why it exists, where it comes from nor how it affects a proce
40、ss. This part of ISO 22514 starts from the premise that it exists and is stable. Process owners should endeavour to understand the sources of variation in their processes. Methods such as flowcharting the process and identifying the inputs and outputs from a process assist in identification of these
41、 variations together with the appropriate use of cause and effect (fishbone) diagrams. It is important for the user of this part of ISO 22514 to appreciate that variations exist that will be of a short- term nature as well as those that will be of a long-term nature and that capability determination
42、s using only the short-term variation might be greatly different to those which have used the long-term variability. When considering short-term variation, a study that uses only the shortest-term variation, sometimes known as a machine study, might be carried out. The method required to carry out s
43、uch a study will be outside the scope of this part of ISO 22514; however, it should be noted that such studies are important and useful. It should be noted that where the capability indices given in this part of ISO 22514 are computed, they only form point estimates of their true values. It is there
44、fore recommended that, wherever possible, the indices confidence intervals are computed and reported. This part of ISO 22514 describes methods by which these can be computed. SANS 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.SANS
45、 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.TECHNICAL REPORT ISO/TR 22514-4:2007(E) ISO 2007 All rights reserved 1 Statistical methods in process management Capability and performance Part 4: Process capability estimates and pe
46、rformance measures 1 Scope This part of ISO 22514 describes process capability and performance measures that are commonly used. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 Basic terms 2.1.1 product result of a process NOTE Process is defi
47、ned in ISO 12207:1995, 3.17 and in ISO 9000:2005, 3.4.1. 2.1.2 characteristic distinguishing feature NOTE 1 A characteristic can be inherent or assigned. NOTE 2 A characteristic can be qualitative or quantitative. NOTE 3 There are various classes of characteristics, such as the following: physical (
48、e.g. mechanical, electrical, chemical or biological characteristics); sensory (e.g. relating to smell, touch, taste, sight, hearing); behavioural (e.g. courtesy, honesty, veracity); temporal (e.g. punctuality, reliability, availability); ergonomic (e.g. physiological characteristic, or related to hu
49、man safety); functional (e.g. maximum speed of an aircraft). ISO 9000:2005, 3.5.1 SANS 22514-4:2008This standard may only be used and printed by approved subscription and freemailing clients of the SABS.ISO/TR 22514-4:2007(E) 2 ISO 2007 All rights reserved2.1.3 quality characteristic inherent characteristic (2.1.2) of a product (2.1.1), process or system related to a requirement NOTE 1 Inherent means existing in something, especially as a permanent characteristic. NOTE 2 A characteristic assigned to a product, p
