Edward Deming (1900-1993) was an American professor of statistics at New York University's graduate school of business administration. He's known for his fourteen key principles of business effectiveness. The principles are close to the Lean principles. His most famous contribution is the iterative four-step management method, called PDCA, which is used to continuously improve processes and products.
PDCA is short for Plan-Do-Check-Act. It starts with a hypothesis, a guess that you want to verify. Then follows the following four steps:
In the first step, the planning step, you decide how to do the change and how to know whether it was successful or not.
The Do step is where you are putting your change into action.
In the Check step, you look at the criteria you decided in the planning step, typically some sort of measurement, and you decide whether it was a success or a failure.
The fourth step is where you act on the result and develop a new hypothesis that you want to...