Plan–do–check–act (PDCA)

Post date: February 15, 2017 by Grace Bourke

In the 1950s, Dr. W. Edwards Deming presented the plan–do–check–act cycle[1] for learning and improvement, based on the continuous improvement cycle of his mentor, Dr. Walter Shewhart. PDCA is four steps for applying the scientific method to any size challenge, problem, or opportunity and to learn from the experience.

  1. Plan: What’s my theory or hypothesis? What does better look like?
  2. Do: Conduct the experiment, implement the plan, or test the hypothesis.
  3. Check: How did it go? Did I get the results I expected? If not, why not? If so, do I know why?
  4. Act: What did I learn? What do I do with the learning? Is there a new goal? Is a new experiment needed? Does the theory get updated?

One of my favorite science experiments was making peanut brittle in high school chemistry using the open flame of a Bunsen burner:

  1. Plan: Our hypothesis was that following the recipe (weighing the ingredients and applying heat) would give us a crisp confection.
  2. Do: We followed the recipe, with a few clarifying questions to the teacher.
  3. Check: Asking the teacher how we should check, he asked. “How did it taste?” I wrote in my lab book, “It was yummy.”
  4. Act: I learned that Chemistry wasn’t so mysterious – it used recipes that could be learned, followed, and improved.

Making peanut brittle again, I merged recipes because one didn’t have enough peanuts and the other made too large of a batch. At work, the experiment might be a modification to a process or creating a new process. Experimenting through PDCA can help with learning a new software program, fixing a problem for patients, or building a new process.


[1] The cycle is also referred to as plan–do–study–act (PDSA).