In order to impress government regulators of this natural monopoly with the high quality of their service, Shewhart's first assignment was to improve the voice clarity of the carbon transmitters in the company's telephone handsets.

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 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.

He possessed a strong operationalist outlook, largely absorbed from the writings of pragmatist philosopher Clarence Irving Lewis, and this influenced his statistical practice.

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 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.

[5] To celebrate his quasquicentennial (125th) birth anniversary, the journal Quality Technology and Quantitative Management (ISSN 1684-3703) published a special issue in on "Advances in the Theory and Application of Statistical Process Control".

[6] 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.