Walter A. Shewhart
Walter A. Shewhart, as mentioned earlier, was a statistician at Bell Laboratories who studied randomness in industrial processes. He developed a system that permitted workers to
determine whether the variability of a process was truly random or due to assignable . If a process exhibited only random variation, it was considered to he "in control." II a
process exhibited nonrandom variation, the cause for the variation had to be identified and
addressed in order for the process to be brought back into control, In addition to eloping the foundations for modern statistical process control. Shew hart also (lei eloped the "plan-do-check-act" (PDCA) cycle shown in Exhibit 6.2. Prior to the PDC).. cycle. typically managed activities as though they hall id beginning and end points. The PDCA cycle uses a circular model to the' need for con improvement. Shewhart's pioneering work in on both Deming and Juran.