The Deming cycle is a four-stage process used for solving problems in business. It is also called the Deming wheel, but is arguably better known as PDCA. This stands for plan, do, check, act.
The first stage of the Deming cycle is planning. In comparison to most business planning, there is a particular emphasis on working out what is needed to reach a very specific target outcome. In many cases, the process is designed to improve procedures by refining the planned outcome in a more specific manner.
The second stage is do. This simply involves trying out the process that has been planned in a practical setting. Usually this is done on as small a scale as possible while still getting useful results. The third stage is check, sometimes listed as study. This involves assessing or measuring the results and then comparing them to the expected outcomes to detect any differences.
The final stage of the Deming cycle is to act. This involves first analyzing the differences between the expected and actual outcome. The idea is to find where in the process the differences were caused, assess what changes need to be made to rectify this, and then carry out these changes.
After making the changes, the business goes through the cycle again. It then assesses and rectifies and remaining or newly created differences between expected and actual outcomes. The business continues going through the cycle until the expected and actual outcomes are the same and no further changes are necessary.
The Deming cycle takes its name from William Edwards Deming. He was an American professor and statistician who developed several management and organizational strategies during the mid- to late-20th century. He was best known for his work in Japan and with the Ford Motor Company.
Another name for the cycle is the Shewhart cycle. This name comes from Walter Andrew Shewhart, another American statistician. Deming is believed to have used "Shewhart cycle" when he first referred to the process, later switching to PDSA, standing for plan, do, study, act.
It's notable that the structure and basis of the Deming cycle is somewhat reminiscent of the scientific method. This is the cycle by which a hypothesis is developed, experiments are carried out, the results are assessed, and the hypothesis is revised and retested. The equivalent to the Deming cycle's completion stage is for the hypothesis to be widely accepted and confirmed as correct.