Shewhart obtained his doctorate and after a brief spell as an academic joined the Western Electric Company. Western Electric were hardware suppliers to Bell Telephone who had already realized the importance of variation.
Shewhart formalized the concept of "assignable" and "chance" causes (now usually known as "common" and "special" causes) and introduced the control chart in 1924.
Shewhart also developed his Learning and Improvement Cycle of Plan, Do, Study, Act (PDSA). Shewhart was a mentor to Deming who popularized the cycle as Plan, Do, Check, Act.
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