The Benefits of PDCA

Use this cycle for continual process improvement

by Corinne N. Johnson, editorial assistant

The plan-do-check-act (PDCA) cycle is a well-known model for continual process improvement (CPI).1 It teaches organizations to plan an action, do it, check to see how it conforms to the plan and act on what has been learned.2

The PDCA cycle is made up of four steps for improvement or change (see Figure 1):3

1. Plan: Recognize an opportunity, and plan the change.

2. Do: Test the change.

3. Check: Review the test, analyze the results and identify learnings.

4. Act: Take action based on what you learned in the check step. If the change was successful, incorporate the learnings from the test into wider changes. If not, go through the cycle again with a different plan.

A brief history

The PDCA cycle is also known by two other names, the Shewhart cycle and the Deming cycle.

Walter A. Shewhart first discussed the concept of PDCA in his 1939 book, Statistical Method From the Viewpoint of Quality Control.

Shewhart said the cycle draws its structure from the notion that constant evaluation of management practices, as well as the willingness of management to adopt and disregard unsupported ideas, is key to the evolution of a successful enterprise.4

W. Edwards Deming was the one who first coined the term "Shewhart cycle" for PDCA, naming it after his mentor and teacher at Bell Laboratories in New York. Deming promoted PDCA as a primary means of achieving CPI.5 He also referred to the PDCA cycle as the PDSA cycle ("S" for study).

Deming is credited with encouraging the Japanese in the 1950s to adopt PDCA. The Japanese eagerly embraced PDCA and other quality concepts, and to honor Deming for his instruction, they refer to the PDCA cycle as the Deming cycle.

Parking ticket example

Here's an example of PDCA in action:


  • Identify the problem. A parking ticket was sent to me by mistake. My name was on the ticket, but the license and registration belonged to someone else with my last name. The post office forwarded his mail to me, assuming we were related because we have the same last name.
  • Analyze the problem. How was the mistake made? The post office forwarded someone else's mail to me. What effect might it have? If the ticket goes unpaid, it may prevent me from being able to buy and register a car in the future.


  • Develop solutions. Should I ignore the ticket, and rip it up? Should I call the number for the parking violations bureau on the ticket and explain the situation? Should I call a friend or family member who is a police officer or lawyer and let that person handle it?
  • Implement the solution. I decided to call the parking violations bureau and make any additional phone calls based on information given to me to clear up the mistake.


  • Evaluate the results. Calling the local violations bureau did not help. Neither did going to local government agencies and explaining the mistake.
  • Was the desired goal achieved? (If so, go to the act step. If not, go back to the beginning and start over.) No, the desired outcome was not achieved; the ticket mistake had not been fixed. So I went back to the beginning and reviewed the information. I found the number for the state violations bureau and called it. The person there gave me step-by-step instructions to follow to have my name removed from the ticket.


  • Standardize the solution. If the problem ever occurs again, I will contact the state agency directly. To prevent future occurrences, I will tell the post office the wrong person's mail is being sent to my address and have it stopped.


1. Nancy Tague, The Quality Toolbox (Milwaukee: ASQ Quality Press, 1995).

2. ASQ and the Holmes Corp., ASQ's Foundations in Quality Self-Directed Learning Program (Milwaukee: ASQ Quality Press, 1999).

3. Nancy Tague, The Quality Toolbox, see reference 1.

4. "Walter Shewhart: The Godfather of Total Quality Management," www.pathmaker.com/resources/leaders/shewart.asp.

5. ASQ and the Holmes Corp., ASQ's Foundations in Quality Self-Directed Learning Program, see reference 2.

--Indira Ramjit, 02-20-2008

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