The Pre-Six Sigma Eras: William Shewhart's Statistical Control
The beginnings of the Six Sigma history brings us back to the roaring twenties, which was a time when the early developments in science and technology were still rough around the edges. It was during this era that an American statistician named William Shewhart showed how statistical methods could be used to instill quality control in industrial processes. In so doing, the technological invention could be expected to generate more reliable results.
William Shewhart manifested this while working as an engineer at Western Electric Company, where his work included providing technical advice to Bell Telephone Company. Shewhart was instrumental in helping the engineers reduce the frequency of failures and constant process adjustments.
It was at this point that this American statistician developed the framework for the “control chart". The framework subsequently became a widely used tool to keep variations in manufacturing processes under statistical control. In using the said methodology, the trigger factors of the variations were distinguished either as an "assignable cause" or as a "chance cause".
The control chart furnished the means for managing processes in ways that the results of the output could be predicted. The objective was to ensure quality turnout for every batch processed by using the available resources economically.
Those were the roots of the Six Sigma history.
Beginning 1925 through 1956, William Shewhart went into publishing a series of papers about the statistical control system he developed for Bell Telephone. In 1933, the American Society for Testing Materials (ASTM) came to adopt Shewhart’s control chart. During the World War II era, the American War Standards advocated Shewhart's control chart as a means for improving production efficiency.
However, the turning point of the Six Sigma history came about in 1950 when another American statistician championed William Shewhart’s entire concept of statistical control. His name was W. Edwards Deming, to whom the system of rationalizing production-process improvement is attributed.
Deming’s analysis and rationalization concepts were based on William Shewhart’s statistical methods. They later came to be known in the manufacturing industry as Statistical Process Control (SPC) and Total Quality Management (TQM).
Quite interestingly, these concepts became great influences to Japan’s post-war industrial revival. Japan’s corporate managements widely received them as the keys to improving their manufacturing efficiency.