Plan Do Check Act (PDCA) Cycle
At the heart of Kaizen is the Plan Do Check Act (PDCA) Cycle. PDCA is an improvement cycle based on the scientific method of proposing a change in a process, implementing the change, measuring the results, and taking appropriate action. Another name for the PDCA cycle is the Shewhart cycle. It also is known as the Deming Cycle or Deming Wheel after W. Edwards Deming, who introduced the concept in Japan in the 1950s.
Kaizen & Plan Do Check Act (PDCA) Cycle
The PDCA cycle is likely the core principle taught in the training film titled “Improvement in 4 Steps” (Kaizen eno Yon Dankai) to introduce the three TWI “J” programs produced by The Economic and Scientific Section (ESS) group from USA, a task force formed to help with the rebuilding of Japanese industry. This was how “Kaizen”, as a business improvement methodology or concept, was introduced to Japan.
Some organizations prefer another model: Plan Do Study Act (PDSA), although the concept remains largely the same.
Summary of The Plan Do Check Act (PDCA)/ Plan Do Study Act (PDSA) Model
Plan : Plan for the change. Establish the objectives and processes necessary to deliver results in accordance with the expected output (the target or goals). By establishing output expectations, the completeness and accuracy of the specification is also a part of the targeted improvement. When possible start on a small scale to test possible effects.
Do : Implement the plan and execute the new processes, often on a small scale if possible. Collect data for charting and analysis in the following “CHECK” and “ACT” steps.
Check/ Study : Measure the new processes and compare the results against the expected results to ascertain any differences. Look for deviation in implementation from the plan and also look for the appropriateness and completeness of the plan to enable the execution, i.e., “Do”. Charting data can make this much easier to see trends over several PDCA cycles and in order to convert the collected data into information. Information is what you need for the next step “ACT”.
Act : Decide on actions/ changes needed to improve the process. If the CHECK shows that the PLAN that was implemented in DO is an improvement to the prior standard (baseline), then that becomes the new standard (baseline) for how the organization should ACT going forward (new standards are enACTed). If the CHECK shows that the PLAN that was implemented in DO is not an improvement, then the existing standard (baseline) will remain in place.
PDCA is a Never Ending Iteration
A fundamental principle of the scientific method and PDCA is iteration—once a hypothesis is confirmed (or negated), executing the cycle again will extend the knowledge further. Repeating the PDCA cycle can bring us closer to the goal, usually a perfect operation and output.
Deming continually emphasized iterating towards an improved system, hence PDCA should be repeatedly implemented in spirals of increasing knowledge of the system that converge on the ultimate goal, each cycle closer than the previous.
Application of Plan Do Check Act (PDCA)/ Plan Do Study Act (PDSA) model
As a model for continuous improvement.
When starting a new improvement project.
When developing a new or improved design of a process, product or service.
When defining a repetitive work process.
When planning data collection and analysis in order to verify and prioritize problems or root causes.
When implementing any change.