Walter A. Shewhart
Encyclopedia
Walter Andrew Shewhart was an American
physicist
, engineer
and statistician
, sometimes known as the father of statistical quality control.
W. Edwards Deming
said of him:
to Anton and Esta Barney Shewhart, he attended the University of Illinois
before being awarded his doctorate in physics
from the University of California, Berkeley
in 1917.
’s engineers had been working to improve the reliability of their transmission systems. Because amplifiers and other equipment had to be buried underground, there was a business need to reduce the frequency of failures and repairs. When Dr. Shewhart joined the Western Electric Company
Inspection Engineering Department at the Hawthorne Works
in 1918, industrial quality was limited to inspecting finished products and removing defective items. That all changed on May 16, 1924. Dr. Shewhart's boss, George D. Edwards, recalled: "Dr. Shewhart prepared a little memorandum only about a page in length. About a third of that page was given over to a simple diagram which we would all recognize today as a schematic control chart
. That diagram, and the short text which preceded and followed it, set forth all of the essential principles and considerations which are involved in what we know today as process quality control." Shewhart's work pointed out the importance of reducing variation in a manufacturing process and the understanding that continual process-adjustment in reaction to non-conformance actually increased variation and degraded quality.
Shewhart framed the problem in terms of assignable-cause and chance-cause variation and introduced the control chart as a tool for distinguishing between the two. Shewhart stressed that bringing a production process into a state of statistical control, where there is only chance-cause variation, and keeping it in control, is necessary to predict future output and to manage a process economically. Dr. Shewhart created the basis for the control chart and the concept of a state of statistical control by carefully designed experiments. While Dr. Shewhart drew from pure mathematical statistical theories, he understood data from physical processes never produce a "normal distribution curve" (a Gaussian distribution, also commonly referred to as a "bell curve
"). He discovered that observed variation in manufacturing data did not always behave the same way as data in nature (Brownian motion
of particles). Dr. Shewhart concluded that while every process displays variation, some processes display controlled variation that is natural to the process, while others display uncontrolled variation that is not present in the process causal system at all times.
Shewhart worked to advance the thinking at Bell Telephone Laboratories
from their foundation in 1925 until his retirement in 1956, publishing a series of papers in the Bell System Technical Journal
.
His work was summarized in his book Economic Control of Quality of Manufactured Product (1931).
Shewhart’s charts were adopted by the American Society for Testing and Materials
(ASTM) in 1933 and advocated to improve production during World War II
in American War Standards Z1.1-1941, Z1.2-1941 and Z1.3-1942.
and statistical inference
. The title of his second book Statistical Method from the Viewpoint of Quality Control (1939) asks the audacious question: What can statistical practice, and science
in general, learn from the experience of industrial quality control?
Shewhart's approach to statistics
was radically different from that of many of his contemporaries. He possessed a strong operationalist outlook, largely absorbed from the writings of pragmatist
philosopher C. I. Lewis, and this influenced his statistical practice. In particular, he had read Lewis's Mind and the World Order many times. Though he lectured in England
in 1932 under the sponsorship of Karl Pearson
(another committed operationalist) his ideas attracted little enthusiasm within the English statistical tradition. The British Standards nominally based on his work, in fact, diverge on serious philosophical and methodological issues from his practice.
His more conventional work led him to formulate the statistical idea of tolerance interval
s and to propose his data presentation rules, which are listed below:
Walter Shewhart visited India
in 1947-48 under the sponsorship of P. C. Mahalanobis
of the Indian Statistical Institute
. Shewhart toured the country, held conferences and stimulated interest in statistical quality control among Indian industrialists.
He died at Troy Hills, New Jersey in 1967.
s W. Edwards Deming
and Raymond T. Birge. The two had been deeply intrigued by the issue of measurement error in science and had published a landmark paper in Reviews of Modern Physics in 1934. On reading of Shewhart's insights, they wrote to the journal to wholly recast their approach in the terms that Shewhart advocated.
The encounter began a long collaboration between Shewhart and Deming
that involved work on productivity
during World War II
and Deming
's championing of Shewhart's ideas in Japan
from 1950 onwards. Deming
developed some of Shewhart's methodological proposals around scientific inference and named his synthesis the Shewhart cycle.
, Deming
wrote of Shewhart:
He was founding editor of the Wiley Series in Mathematical Statistics, a role that he maintained for twenty years, always championing freedom of speech
and confident to publish views at variance with his own.
His honours included:
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. |pages=155 p. |chapter= |chapterurl= |quote= }}
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
, engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
and statistician
Statistician
A statistician is someone who works with theoretical or applied statistics. The profession exists in both the private and public sectors. The core of that work is to measure, interpret, and describe the world and human activity patterns within it...
, sometimes known as the father of statistical quality control.
W. Edwards Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
said of him:
- As a statistician, he was, like so many of the rest of us, self-taught, on a good background of physics and mathematics.
Early life and education
Born in New Canton, IllinoisNew Canton, Illinois
New Canton is an incorporated town in Pleasant Vale Township, Pike County, Illinois, United States. The population was 417 at the 2000 census.-Geography:New Canton is located at ....
to Anton and Esta Barney Shewhart, he attended the University of Illinois
University of Illinois at Urbana-Champaign
The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...
before being awarded his doctorate in physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
from the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
in 1917.
Work on industrial quality
Bell TelephoneBell Telephone
Bell Telephone may refer to:* Bell Telephone Company, several telephone companies with similar names* Bell Telephone Building , various* The Bell Telephone Hour, a long-running radio and television concert program...
’s engineers had been working to improve the reliability of their transmission systems. Because amplifiers and other equipment had to be buried underground, there was a business need to reduce the frequency of failures and repairs. When Dr. Shewhart joined the Western Electric Company
Western Electric
Western Electric Company was an American electrical engineering company, the manufacturing arm of AT&T from 1881 to 1995. It was the scene of a number of technological innovations and also some seminal developments in industrial management...
Inspection Engineering Department at the Hawthorne Works
Hawthorne Works
The Hawthorne Works, in Cicero, Illinois, was a large factory complex built by Western Electric starting in 1905 and operating until 1983. It had 45,000 employees at the height of its operations. Besides telephone equipment, the factory produced a wide variety of consumer products, including...
in 1918, industrial quality was limited to inspecting finished products and removing defective items. That all changed on May 16, 1924. Dr. Shewhart's boss, George D. Edwards, recalled: "Dr. Shewhart prepared a little memorandum only about a page in length. About a third of that page was given over to a simple diagram which we would all recognize today as a schematic control chart
Control chart
Control charts, also known as Shewhart charts or process-behaviour charts, in statistical process control are tools used to determine whether or not a manufacturing or business process is in a state of statistical control.- Overview :...
. That diagram, and the short text which preceded and followed it, set forth all of the essential principles and considerations which are involved in what we know today as process quality control." Shewhart's work pointed out the importance of reducing variation in a manufacturing process and the understanding that continual process-adjustment in reaction to non-conformance actually increased variation and degraded quality.
Shewhart framed the problem in terms of assignable-cause and chance-cause variation and introduced the control chart as a tool for distinguishing between the two. Shewhart stressed that bringing a production process into a state of statistical control, where there is only chance-cause variation, and keeping it in control, is necessary to predict future output and to manage a process economically. Dr. Shewhart created the basis for the control chart and the concept of a state of statistical control by carefully designed experiments. While Dr. Shewhart drew from pure mathematical statistical theories, he understood data from physical processes never produce a "normal distribution curve" (a Gaussian distribution, also commonly referred to as a "bell curve
Bell curve
Bell curve can refer to:* A Gaussian function, a specific kind of function whose graph is a bell-shaped curve* Normal distribution, whose density function is a Gaussian function...
"). He discovered that observed variation in manufacturing data did not always behave the same way as data in nature (Brownian motion
Brownian motion
Brownian motion or pedesis is the presumably random drifting of particles suspended in a fluid or the mathematical model used to describe such random movements, which is often called a particle theory.The mathematical model of Brownian motion has several real-world applications...
of particles). Dr. Shewhart concluded that while every process displays variation, some processes display controlled variation that is natural to the process, while others display uncontrolled variation that is not present in the process causal system at all times.
Shewhart worked to advance the thinking at Bell Telephone Laboratories
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
from their foundation in 1925 until his retirement in 1956, publishing a series of papers in the Bell System Technical Journal
Bell System Technical Journal
The Bell System Technical Journal was the in-house scientific journal of Bell Labs that was published from 1922 to 1983.- Notable papers :...
.
His work was summarized in his book Economic Control of Quality of Manufactured Product (1931).
Shewhart’s charts were adopted by the American Society for Testing and Materials
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
(ASTM) in 1933 and advocated to improve production during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
in American War Standards Z1.1-1941, Z1.2-1941 and Z1.3-1942.
Later work
From the late 1930s onwards, Shewhart's interests expanded out from industrial quality to wider concerns in scienceScience
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
and statistical inference
Statistical inference
In statistics, statistical inference is the process of drawing conclusions from data that are subject to random variation, for example, observational errors or sampling variation...
. The title of his second book Statistical Method from the Viewpoint of Quality Control (1939) asks the audacious question: What can statistical practice, and science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
in general, learn from the experience of industrial quality control?
Shewhart's approach to statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
was radically different from that of many of his contemporaries. He possessed a strong operationalist outlook, largely absorbed from the writings of pragmatist
Pragmatist
Pragmatist may refer to:*A person who subscribes to pragmatism, a field of philosophy*A person who subscribes to pragmaticism, Charles Sanders Peirce's post-1905 branch of philosophy...
philosopher C. I. Lewis, and this influenced his statistical practice. In particular, he had read Lewis's Mind and the World Order many times. Though he lectured in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in 1932 under the sponsorship of Karl Pearson
Karl Pearson
Karl Pearson FRS was an influential English mathematician who has been credited for establishing the disciplineof mathematical statistics....
(another committed operationalist) his ideas attracted little enthusiasm within the English statistical tradition. The British Standards nominally based on his work, in fact, diverge on serious philosophical and methodological issues from his practice.
His more conventional work led him to formulate the statistical idea of tolerance interval
Tolerance interval
A tolerance interval is a statistical interval within which, with some confidence level, a specified proportion of a population falls.A tolerance interval can be seen as a statistical version of a probability interval. If we knew a population's exact parameters, we would be able to compute a range...
s and to propose his data presentation rules, which are listed below:
- Data have no meaning apart from their context.
- Data contain both signal and noise. To be able to extract information, one must separate the signal from the noise within the data.
Walter Shewhart visited India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
in 1947-48 under the sponsorship of P. C. Mahalanobis
Prasanta Chandra Mahalanobis
Prasanta Chandra Mahalanobis FRS was an Indian scientist and applied statistician. He is best remembered for the Mahalanobis distance, a statistical measure. He made pioneering studies in anthropometry in India...
of the Indian Statistical Institute
Indian Statistical Institute
Indian Statistical Institute is a public research institute and university in Kolkata's northern outskirt of Baranagar, India founded by Prasanta Chandra Mahalanobis in 1931...
. Shewhart toured the country, held conferences and stimulated interest in statistical quality control among Indian industrialists.
He died at Troy Hills, New Jersey in 1967.
Influence
In 1938 his work came to the attention of physicistPhysicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
s W. Edwards Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
and Raymond T. Birge. The two had been deeply intrigued by the issue of measurement error in science and had published a landmark paper in Reviews of Modern Physics in 1934. On reading of Shewhart's insights, they wrote to the journal to wholly recast their approach in the terms that Shewhart advocated.
The encounter began a long collaboration between Shewhart and Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
that involved work on productivity
Productivity
Productivity is a measure of the efficiency of production. Productivity is a ratio of what is produced to what is required to produce it. Usually this ratio is in the form of an average, expressing the total output divided by the total input...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
and Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
's championing of Shewhart's ideas in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
from 1950 onwards. Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
developed some of Shewhart's methodological proposals around scientific inference and named his synthesis the Shewhart cycle.
Achievements and honours
In his obituary for the American Statistical AssociationAmerican Statistical Association
The American Statistical Association , is the main professional US organization for statisticians and related professions. It was founded in Boston, Massachusetts on November 27, 1839, and is the second oldest, continuously operating professional society in the United States...
, Deming
W. Edwards Deming
William Edwards Deming was an American statistician, professor, author, lecturer and consultant. He is perhaps best known for his work in Japan...
wrote of Shewhart:
As a man, he was gentle, genteel, never ruffled, never off his dignity. He knew disappointment and frustration, through failure of many writers in mathematical statistics to understand his point of view.
He was founding editor of the Wiley Series in Mathematical Statistics, a role that he maintained for twenty years, always championing freedom of speech
Freedom of speech
Freedom of speech is the freedom to speak freely without censorship. The term freedom of expression is sometimes used synonymously, but includes any act of seeking, receiving and imparting information or ideas, regardless of the medium used...
and confident to publish views at variance with his own.
His honours included:
- Founding member, fellow and president of the Institute of Mathematical StatisticsInstitute of Mathematical StatisticsThe Institute of Mathematical Statistics is an international professional and scholarly society devoted to the development, dissemination, and application of statistics and probability. The Institute currently has about 4,000 members in all parts of the world...
; - Founding member, first honorary member and first Shewhart MedalShewhart MedalThe Shewhart Medal, named in honour of Walter A. Shewhart, is awarded annually by the American Society for Quality for ...outstanding technical leadership in the field of modern quality control, especially through the development to its theory, principles, and techniques. The first medal was...
ist of the American Society for QualityAmerican Society for QualityAmerican Society for Quality , formerly known as American Society for Quality Control , is a knowledge-based global community of quality control experts, with nearly 85,000 members dedicated to the promotion and advancement of quality tools, principles, and practices in their workplaces and in...
; - Fellow and President of the American Statistical AssociationPresident of the American Statistical AssociationThe President of the American Statistical Association is the head of the American Statistical Association . According to the association's bylaws, the president is an officer, and a member of the board of directors and of the executive committee. Elections for the position are held annually, in...
; - Fellow of the International Statistical InstituteInternational Statistical InstituteThe International Statistical Institute is a professional association of statisticians. The Institut International de Statistique or International Statistical Institute was founded in 1885 although there had been international congresses from 1853.. The Institute publishes a variety of books and...
; - Honorary fellow of the Royal Statistical SocietyRoyal Statistical SocietyThe Royal Statistical Society is a learned society for statistics and a professional body for statisticians in the UK.-History:It was founded in 1834 as the Statistical Society of London , though a perhaps unrelated London Statistical Society was in existence at least as early as 1824...
; - Holley medal of the American Society of Mechanical EngineersAmerican Society of Mechanical EngineersThe American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....
; - Honorary Doctor of Science, Indian Statistical InstituteIndian Statistical InstituteIndian Statistical Institute is a public research institute and university in Kolkata's northern outskirt of Baranagar, India founded by Prasanta Chandra Mahalanobis in 1931...
, Calcutta.
See also
- Control chartControl chartControl charts, also known as Shewhart charts or process-behaviour charts, in statistical process control are tools used to determine whether or not a manufacturing or business process is in a state of statistical control.- Overview :...
- Common cause and special causeCommon cause and special causeCommon- and special-causes are the two distinct origins of variation in a process, as defined in the statistical thinking and methods of Walter A. Shewhart and W. Edwards Deming...
- Analytic and enumerative statistical studiesAnalytic and enumerative statistical studiesAnalytic and enumerative statistical studies are two types of scientific studies:In any statistical study the ultimate aim is to provide a rational basis for action. Enumerative and analytic studies differ by where the action is taken...
Books
. |pages=433 p. |chapter= |chapterurl= |quote= }}. |pages=501 p. |chapter= |chapterurl= |quote= }}
. |pages=155 p. |chapter= |chapterurl= |quote= }}
External links
- ASQ Shewhart page
- Walter A Shewhart on the Portraits of Statisticians page.
