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Walter A. Shewhart

Walter Andrew Shewhart (March 18, 1891 - March 11, 1967) was a physicist, engineer and statistician, sometimes known as the father of statistical quality control. Born New Canton, Illinois to Anton and Esta Barney Shewhart, he attended the University of Illinois before being awarded his doctorate in physics from the University of California in 1917.

As W. Edwards Deming 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.

Table of contents
1 Work on industrial quality
2 Later work
3 Influence
4 Achievements and honours
6 Publications
7 Bibliography
8 External links

Work on industrial quality

Following a brief spell as an academic, in 1918 Shewhart joined the Western Electric Company, a manufacturer of telephony hardware for the Bell Telephone Company. Bell Telephone’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. Bell Telephone had already realised the importance of reducing variation in a manufacturing process. Moreover, they had realised that continual process-adjustment in reaction to non-conformance actually increased variation and degraded quality. In 1924, 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. 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 summarised in his book Economic Control of Quality of Manufactured Product (1931).

Shewhart’s charts were adopted by the American Society for Testing 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.

Later work

From the late 1930s onwards, Shewhart's interests expanded out from industrial quality to wider concerns in science 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 metodological issues from his practice.

His more conventional work led him to formulate the statistical idea of tolerance intervals and to propose his rules for data presentation.

Shewhart visited India three times under the sponsorship of P. C. Mahalanobis. One visit in the 1950s resulted in a collaboration with Genechi Taguchi (& R. A. Fisher? - does anyone have any info on Shewhart in India?). He also visited Japan. (Does anyone know anything about Shewhart in Japan?)

He died at Troy Hills, New Jersey in 1967.


In 1938 his work came to the attention of physicists 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.

During the 1990s, Shewhart's genius was rediscovered by a third generation of industrial managers as the Six Sigma approach.

Achievements and honours

In his obituary for the American Statistical Association, Deming 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 and confident to publish views at variance with his own.

His honours included:


Both pure and applied science have gradually pushed further and further the requirements for accuracy and precision. However, applied science, particularly in the mass production of interchangeable parts, is even more exacting than pure science in certain matters of accuracy and precision.



External links