Shewhart

Walter A. Shewhart was an American physicist, engineer, and statistician who laid the foundations of statistical quality control. While at Bell Telephone Laboratories in the 1920s and 1930s, he developed the control chart, a statistical tool for distinguishing between natural variation in a process and variation arising from identifiable causes. The chart enables ongoing monitoring of a production process and the identification of when processes are out of statistical control, prompting investigation and corrective action rather than after-the-fact inspection.

He introduced key concepts that became central to quality management, including the idea of a state of statistical control, and the distinction between common cause variation and special cause variation. He also articulated the iterative cycle of planning, implementation, and study of processes as a framework for improvement, commonly associated with the Plan-Do-Check-Act cycle.

Shewhart’s writings, notably Economic Control of Quality of Manufactured Product and Statistical Method from the Viewpoint of Quality Control, presented methods for applying statistics to manufacturing and for improving quality through understanding process variation. His work formed the basis for statistical process control and influenced manufacturing organizations worldwide, helping to spur quality initiatives in the postwar era and influencing later quality leaders such as Deming and Juran. He is often regarded as the founder or father of statistical quality control.