Another name of the PDCA (see PDSA) in honor of W. Edwards Deming (1900-1993) and based on the work of Walter A. Shewhart (1891-1967) First introduced by W. A. Shewhart in “Statistical method from the viewpoint of Quality Control” in 1939, originally introduced as a linear sequence of 3 steps and subsequently evolved into the 4-step cycle by Shewhart. Shewhart was one of Deming’s mentors, and introduced him to the cycle. Deming built on Shewhart’s concept emphasizing the interactions between the four steps and popularizing the cycle in the area of Total Quality Management.