Remembering Walter A. Shewhart's Contribution to the Quality World
March 2, 2009
Walter Shewhart was a giant among giants in the quality movement during the first half of the 20th century. His mentoring of other engineers at Western Electric and his groundbreaking work with control charts arguably led a quality revolution and launched the quality profession.
BackgroundWalter Andrew Shewhart was born to Anton and Esta Barney Shewhart on March 18, 1891, in New Canton, IL. Shewhart died on March 11, 1967, in Troy Hills, NJ. He attended the University of Illinois receiving bachelor’s and master’s degrees. In 1914, he married Edna Hart and moved to California where he earned his doctoral degree in physics while studying as a Whiting Fellow at the University of California, Berkeley, in 1917.
He had brief stints of teaching at University of Illinois, University of California at Berkeley, and La Crosse State Teachers College (renamed Wisconsin State University), but his academic career was short-lived.
In 1918, Shewhart joined the inspection engineering department of the Western Electric Co. in Hawthorne, IL. Western Electric manufactured telephone hardware for Bell Telephone Co. Although no one could have realized it at the time, Shewhart would alter the course of industrial history.
Shewhart was part of a group of people who were all destined to become famous in their time. This group included Harold Dodge and Harry Romig, known for their work on product sampling plans. George D. Edwards, who became the first president of the American Society for Quality Control (renamed American Society for Quality in 1997), was Shewhart’s supervisor.
Shewhart mentored many during his tenure, including Joseph M. Juran. During the summers of 1925 and 1926, W. Edwards Deming worked as an intern at the Hawthorne, IL, plant where he became interested in Shewhart’s work.
Shewhart's ContributionEngineers at Bell Telephone had been working to improve the reliability of their transmissions systems. Business dictated a need to reduce the frequency of failures and repairs to their amplifiers, connectors and other equipment that were buried underground. Bell Telephone had already realized that reducing variation in manufacturing processes would have a positive impact on repair costs. At the same time the company determined that continual adjustments in process parameters reacting to non-conformances resulted in increased variation and a degradation of quality.
Bell Telephone’s discoveries in product variation resulted in the institution of an inspection program, ensuring specification and quality standards to avoid sending defective products to customers. Even though this program was somewhat effective, it was very costly to deal with inspecting and sorting of finished goods.
By 1924, Shewhart determined the problem of variability in terms of assignable cause and chance cause (Deming referred to this as common cause). On May 16, 1924, Shewhart prepared a memorandum of less than one page in length and forwarded it to his manager, George Edwards. About 1/3 of the page was devoted to a simple diagram that we would today recognize as a control chart. This memorandum set forth the essential principles and considerations that became known as process quality control.
Shewhart’s principle was that bringing a process into a state of statistical control would allow the distinction between assignable and chance cause variations. By keeping the process in control, it would be possible to predict future output and to economically manage processes. This was the birth of the modern scientific study of process control.
SPC Moves MainstreamAt its creation in 1925, Shewhart moved to the Bell Telephone Laboratories working to advance his theories and to bring together the disciplines of statistics, engineering and economics.
In 1931 he published a book, “Economic Control of Quality of Manufactured Product.” It challenged the inspection-based approach to quality and introduced the modern era of quality management. Up until this time, statistical process control was largely a Bell Telephone quality tool. Shewhart’s book popularized statistical control and its use then spread throughout industry.
From the 1930s forward, Shewhart’s interests expanded from industrial quality to wider concerns in science and statistical inference. In 1934, W. Edwards Deming and another physicist, Raymond T. Birge, published a paper on measurement error in science. However, after collaboration with Shewhart, they recast their approach and launched a long collaboration between Shewhart and Deming.
Shewhart’s charts were adopted by the American Society for Testing Materials (ASTM) in 1933. Shewhart and Deming impacted the improvement of production material during World War II in American War Standards Z1.1-1941, Z1.2-1941 and Z1.3-1942. Frequently, he was called upon as a consultant to the U.S. War Department, the United Nations and the government of India.
Deming continued to champion Shewhart’s ideas, methodologies and theories throughout his career. While working with Japan, Deming further developed some of Shewhart’s methodological proposals of scientific interference, which had been named the Shewhart Cycle and was represented by the plan-do-check-act elements.
Shewhart lectured extensively on the subjects of quality control and applied statistics in India, at the University of London, at Stevens Institute of Technology and at the graduate schools of the U.S. Department of Agriculture. He also was a member of many societies and governmental agencies.
During the 1990s Shewhart’s work was rediscovered by a third generation of industrial engineers and managers, and this time it was repackaged and incorporated into the Six Sigma approach.
Shewhart received many honors and awards that include:
- Holley Medal of the American Society of Mechanical Engineers
- ASQ’s 1st Honorary Member
- Founding Member and Fellow of the Institute of Mathematical Statistics
- Fellow of the American Statistical Association
- Fellow of the International Statistical Institute
- Fellow of the Royal Society of Mechanical Engineers
Upon his death in 1967, there were a multitude of commentaries from many contributors who were themselves important figures in the development of the quality field. An excerpt from a speech by the chairman of the committee that awarded the first ASQ Shewhart Medal captured Shewhart’s character in the following:
“Shewhart’s legacy lives in mementos of him-a simple bowl and some numbered chips, a bronze medal, some books and writings. It lives in the succession of other prominent individuals he influenced, and it lives in the society of professionals who carry on the work he started.”