Statistical process control: Difference between revisions

Revision as of 21:17, 8 November 2023

Revision as of 10:55, 5 December 2023

Line 12:

== History ==

Statistical process control was pioneered by [[Walter A. Shewhart]] at [[Bell Laboratories]] in the early 1920s. Shewhart developed the control chart in 1924 and the concept of a state of statistical control. Statistical control is equivalent to the concept of [[exchangeability]]<ref>{{harvnb|Barlow & |Irony (|1992)}}</ref><ref>{{harvnb|Bergman (|2009)}}</ref> developed by logician [[William Ernest Johnson]] also in 1924 in his book ''Logic, Part III: The Logical Foundations of Science''.<ref>{{harvnb|Zabell (|1992)}}</ref> Along with a team at AT&T that included [[Harold F. Dodge|Harold Dodge]] and Harry Romig he worked to put [[Sampling (statistics)|sampling]] inspection on a rational statistical basis as well. Shewhart consulted with Colonel Leslie E. Simon in the application of control charts to munitions manufacture at the Army's [[Picatinny Arsenal]] in 1934. That successful application helped convince Army Ordnance to engage AT&T's George Edwards to consult on the use of statistical quality control among its divisions and contractors at the outbreak of World War II.

[[W. Edwards Deming]] invited Shewhart to speak at the Graduate School of the U.S. Department of Agriculture and served as the editor of Shewhart's book ''Statistical Method from the Viewpoint of Quality Control'' (1939), which was the result of that lecture. Deming was an important architect of the quality control short courses that trained American industry in the new techniques during WWII. The graduates of these wartime courses formed a new professional society in 1945, the [[American Society for Quality Control]], which elected Edwards as its first president. Deming travelled to Japan during the Allied Occupation and met with the Union of Japanese Scientists and Engineers (JUSE) in an effort to introduce SPC methods to Japanese industry.<ref>{{cite book |author-link=W. Edwards Deming, |first=W. Edwards, |last=Deming |title=Lectures on statistical control of quality., |publisher=Nippon Kagaku Gijutsu Remmei, 1950|edition=Rev. 2nd |date=1952 |oclc=2518026 }}</ref><ref>Deming, W. Edwards and Dowd S. John (translator) Lecture to Japanese Management, Deming Electronic Network Web Site, 1950 (from a Japanese transcript of a lecture by Deming to "80% of Japanese top management" given at the Hotel de Yama at Mr. Hakone in August 1950)</ref>

==='Common' and 'special' sources of variation===

{{Main|Common cause and special cause (statistics)}}

Shewhart read the new statistical theories coming out of Britain, especially the work of [[William Sealy Gosset]], [[Karl Pearson]], and [[Ronald Fisher]]. However, he understood that data from physical processes seldom produced a [[normal distribution]] curve (that is, a [[Gaussian distribution]] or '[[Normal distribution|bell curve]]'). He discovered that data from measurements of variation in manufacturing did not always behave the same way as data from measurements of natural phenomena (for example, [[Brownian motion]] of particles). Shewhart concluded that while every process displays variation, some processes display variation that is natural to the process ("''common''" sources of variation); these processes he described as being ''in (statistical) control''. Other processes additionally display variation that is not present in the causal system of the process at all times ("''special''" sources of variation), which Shewhart described as ''not in control''.<ref>{{cite book |title=Why SPC? |agency=British Deming Association |publisher=SPC Press, Inc.|isbn=978-0-945320-17-3 |year=1992}}</ref>

===Application to non-manufacturing processes===

Statistical process control is appropriate to support any repetitive process, and has been implemented in many settings where for example [[ISO 9000]] quality management systems are used, including financial auditing and accounting, IT operations, health care processes, and clerical processes such as loan arrangement and administration, customer billing etc. Despite criticism of its use in design and development, it is well-placed to manage semi-automated data governance of high-volume data processing operations, for example in an enterprise data warehouse, or an enterprise data quality management system.<ref>{{cite book |first=Larry |last=English |title=Improving Data Warehouse and Business Information Quality : Methods for Reducing Costs and Increasing Profits |publisher=Wiley |date=1999 |isbn=978-0-471-25383-9 }}</ref>

In the 1988 [[Capability Maturity Model]] (CMM) the [[Software Engineering Institute]] suggested that SPC could be applied to software engineering processes. The Level 4 and Level 5 practices of the Capability Maturity Model Integration ([[CMMI]]) use this concept.

The application of SPC to non-repetitive, knowledge-intensive processes, such as research and development or systems engineering, has encountered skepticism and remains controversial.<ref>{{cite journal |first1=Bob |last1=Raczynski and [[|author2-link=Dr Bill Curtis |first2=Bill |last2=Curtis]] (2008)|title=Point/Counterpoint: Counterpoint Argument: Software Data Violate SPC's Underlying Assumptions, |journal=IEEE Software, May/June|volume=25 2008,|issue=3 Vol.|pages=49–51 25,|date=May–June No. 3,2008 pp|doi=10.1109/MS.2008.68 49-51}}</ref><ref>{{cite journal |first=Robert V. |last=Binder (1997) |title=Can a Manufacturing Quality Model Work for Software?, |journal=IEEE Software, September/October|volume=14 |issue=5 |pages=101–5 |date=September–October 1997, pp|doi=10.1109/52.605937 101-105|s2cid=40550515 }}</ref><ref>{{Cite web|last=Raczynski|first=Bob|date=February 20, 2009|title=Is Statistical Process Control Applicable to Software Development Processes?|url=https://www.stickyminds.com/article/statistical-process-control-applicable-software-development-processes|website=StickyMinds|language=en}}</ref>

In ''No Silver Bullet'', [[Fred Brooks]] points out that the complexity, conformance requirements, changeability, and invisibility of software<ref>{{Cite journal |author-link=Fred Brooks | last1 = Brooks, Jr. | first1 = F. P., J.| doi = 10.1109/MC.1987.1663532 | title = No Silver Bullet—Essence and Accidents of Software Engineering | journal = Computer | volume = 20 | issue = 4 | pages = 10–19 | year = 1987 | url = http://faculty.salisbury.edu/~xswang/Research/Papers/SERelated/no-silver-bullet.pdf| citeseerx = 10.1.1.117.315}}</ref><ref name="Brooks, Proc. IFIP" >{{cite conference |first=Fred P. |last=Brooks (1986) |title=No Silver Bullet&nbsp;— Essence and Accident in Software Engineering, Proceedings|book-title=Information processing 86: proceedings of the IFIP Tenth10th World ComputingComputer ConferenceCongress|publisher=North-Holland |date=1986, pp.|isbn=978-0-444-70077-3 1069–1076|pages=1069–76 }}</ref> results in inherent and essential variation that cannot be removed. This implies that SPC is less effective in the software development than in, e.g., manufacturing.

==Variation in manufacturing==

Line 67:

When monitoring many processes with control charts, it is sometimes useful to calculate quantitative measures of the stability of the processes. These metrics can then be used to identify/prioritize the processes that are most in need of corrective actions. These metrics can also be viewed as supplementing the traditional [[process capability]] metrics. Several metrics have been proposed, as described in Ramirez and Runger.<ref name="Ramarez2006">{{cite journal

| author1last1 = Ramirez, |first1=B.

| author2last2 = Runger, |first2=G.

|title= Quantitative Techniques to Evaluate Process Stability

|journal= Quality Engineering

|volume=18

|issue=1

|atpages= pp. 53–68

|year=2006 | doi = 10.1080/08982110500403581

|s2cid=109601393

}}</ref>

They are (1) a Stability Ratio which compares the long-term variability to the short-term variability, (2) an ANOVA Test which compares the within-subgroup variation to the between-subgroup variation, and (3) an Instability Ratio which compares the number of subgroups that have one or more violations of the [[Western Electric rules]] to the total number of subgroups.

Line 99 ⟶ 100:

==Bibliography==

{{refbegin}}

*Barlow, R. E. & Irony, T. Z. (1992) "Foundations of statistical quality control" in Ghosh, M. & Pathak, P.K. (eds.) ''Current Issues in Statistical Inference: Essays in Honor of D. Basu'', Hayward, CA: Institute of Mathematical Statistics, 99–112.

*{{cite book |DUPLICATE_last=Barlow |DUPLICATE_first=R.E. |last=Irony |first=T.Z. |editor-last=Ghosh |editor-first=M. |editor2-last=Pathak |editor2-first=P.K. |chapter=Foundations of statistical quality control |chapter-url={{GBurl|qddbFWqbl4YC|p=99}} |title=Current Issues in Statistical Inference: Essays in Honor of D. Basu |publisher=Institute of Mathematical Statistics |___location=Hayward, CA |date=1992 |isbn=978-0-940600-24-9 |pages=99–112 }}

*Bergman, B. (2009) "Conceptualistic Pragmatism: A framework for Bayesian analysis?", ''IIE Transactions'', '''41''', 86–93

*{{cite journal |first=B. |last=Bergman |title=Conceptualistic Pragmatism: A framework for Bayesian analysis? |journal=IIE Transactions |volume=41 |issue= |pages=86–93 |date=2009 |doi=10.1080/07408170802322713 |s2cid=119485220 }}

*Deming, W E (1975) "On probability as a basis for action", ''The American Statistician'', '''29(4)''', 146–152

*{{cite journal |author-link=W. Edward Deming |first=W.E. |last=Deming |title=On probability as a basis for action |journal=The American Statistician |volume=29 |issue=4 |pages=146–152 |date=1975 |doi=10.1080/00031305.1975.10477402 |pmid=1078437 |s2cid=21043630 }}

*—{{cite (1982)book ''|author-mask=1 |first=W.E. |last=Deming |title=Out of the Crisis: Quality, Productivity and Competitive Position'' {{ISBN|date=1982 |isbn=0-521-30553-5 }}

*Grant,{{cite book |first=E. L. (|last=Grant |title=Statistical quality control |publisher= McGraw-Hill|___location= |date=1946) [|isbn=0071004475 |pages= |url=https://catalog.hathitrust.org/Record/003053820?type%5B%5D=all&lookfor%5B%5D=Statistical%20quality%20control%201946&filter%5B%5D=authorStr%3AGrant%2C%20Eugene%20Lodewick%2C%20b.%201897&ft= Statistical quality control] {{ISBN|0071004475}}

*Oakland, J (2002) ''Statistical Process Control'' {{ISBN|0-7506-5766-9}}

*Salacinski,{{cite Tbook (2015)|first=J. ''SPC -|last=Oakland |title=Statistical Process Control''. The|publisher= Warsaw|___location= University|date=2002 of Technology Publishing House. {{ISBN|978isbn=0-837506-78145766-319-29 }}

*{{cite book |first=T. |last=Salacinski |title=SPC — Statistical Process Control |publisher=The Warsaw University of Technology Publishing House |date=2015 |isbn=978-83-7814-319-2 }}

*Shewhart, W A (1931) ''Economic Control of Quality of Manufactured Product'' {{ISBN|0-87389-076-0}}

*{{cite book |first=W.A. |last=Shewhart |title=Economic Control of Quality of Manufactured Product |publisher= American Society for Quality Control|___location= |date=1931 |isbn=0-87389-076-0 }}

*— (1939) ''Statistical Method from the Viewpoint of Quality Control'' {{ISBN|0-486-65232-7}}

*{{Citecite book |urlauthor-mask=https://www1 |first=W.aiagA.org/quality/automotive-core-tools/spc |last=Shewhart |title=Statistical ProcessMethod Controlfrom (SPC)the ReferenceViewpoint Manualof Quality Control |publisher=Automotive Industry Action Group (AIAG)Courier Corporation|others___location= |yeardate=20051939 |editionisbn=20-486-65232-7 }}

*{{Cite book |url=https://www.aiag.org/quality/automotive-core-tools/spc |title=Statistical Process Control (SPC) Reference Manual |publisher=Automotive Industry Action Group (AIAG) |year=2005 |edition=2}}

*Wheeler, D J (2000) ''Normality and the Process-Behaviour Chart'' {{ISBN|0-945320-56-6}}

*{{cite book |first=D.J. |last=Wheeler |title=Normality and the Process-Behaviour Chart |publisher= SPC Press|___location= |date=2000 |isbn=0-945320-56-6 }}

*Wheeler, D J & Chambers, D S (1992) ''Understanding Statistical Process Control'' {{ISBN|0-945320-13-2}}

*Wheeler,{{cite Donaldbook |last1=Wheeler |first1=D.J. (1999).|last2=Chambers ''|first2=D.S.|title=Understanding Variation:Statistical TheProcess KeyControl to Managing Chaos - 2nd Edition''.|publisher= SPC Press,|___location= Inc.|date=1992 {{ISBN|isbn=0-945320-5313-12 }}.

*{{cite book |first=Donald J. |last=Wheeler |title=Understanding Variation: The Key to Managing Chaos |publisher=SPC Press |edition=2nd |date=1999 |isbn=0-945320-53-1 }}

*{{cite book |last1=Wise, |first1=Stephen A. & |last2=Fair, |first2=Douglas C (1998). ''|title=Innovative Control Charting: Practical SPC Solutions for Today's Manufacturing Environment.'' |publisher=ASQ Quality Press. {{ISBN|date=1998 |isbn=0-87389-385-9 }}

*{{ cite journal | authorlast=Zabell, |first=S. L. | title=Predicting the unpredictable | year=1992 | journal=Synthese | volume=90 | issue=2 | page=205 | doi=10.1007/bf00485351|s2cid=9416747 }}

{{refend}}

==External links==

Line 119 ⟶ 122:

<!-- Note: Before adding your company's link, please read [[WP:Spam#External link spamming]] and [[WP:External links#Links normally to be avoided]]. -->

*[http://ocw.mit.edu/courses/mechanical-engineering/2-830j-control-of-manufacturing-processes-sma-6303-spring-2008/ MIT Course - Control of Manufacturing Processes]

*[{{cite web |url=http://www.itl.nist.gov/div898/handbook/index2.htm |title=NIST/SEMATECH Engineeringe-Handbook Statisticsof Handbook]Statistical Methods |date=2012 |doi=10.18434/M32189 |last1=Guthrie |first1=William F. |publisher=National Institute of Standards and Technology }}

<!-- ''It might be useful to refer to an [http://en.wikipedia.org/w/index.php?title=Statistical_process_control&oldid=26022080 older version] when expanding the article.'' -->