Defining the PDCA Cycle

Here's your definitive guide to the Plan, Do, Check, Adjust (PDCA) cycle - one of the pillars of Lean, continuous improvement and operational excellence.

Plan Do Check Adjust (PDCA) is the engine room of continuous improvement. It is the most widely known and used improvement cycle. This simple, yet highly effective, methodology is at the heart of every improvement or learning opportunity in a Lean thinking organisation. However, it may also be the least well understood in practice.

In my experience many organisations follow a 'PDCA lite' version which is really just Plan and Do or simply just Do, Do, Do, Do. They take a shotgun approach to improvement; simply hoping for the best. All too often we waste time, effort and scarce resources on improvement efforts. Our activity is based on hunches and assumptions that are not well conceived, executed or tracked.

Consider PDCA as a scientific approach

The PDCA methodology is based on the scientific approach of prediction, developing a hypothesis, conducting experiments, observing and checking the outcome, applying critical thinking and attempting to learn from the outcome.

The scientific approach has resonated through the ages. The method has driven countless breakthroughs and innovation through time simply by designing and executing experiments. Think Francis Bacon, Galileo Galilei, Thomas Edison to name a few. As human beings we naturally think and behave this way - particularly as children.

We experiment with the world around us to learn, to grow, and to develop our knowledge through continual trial and error. Consider how we learn to walk, talk and engage with the wide world around us. This continues for us throughout life as we learn and adapt to our situation and current circumstances. We evolve and grow toward our objectives both professional and personal.

These days the method is visualised as a circle with the four quadrants of the PDCA process. The circular motion is an indication of the sequence of the method. Plus it's a reminder of the perpetual nature of the continuous process improvement. Fun fact - it wasn't always a circle!

The first to show it as such was Walter Shewhart, also known as 'the father of statistical quality control'. However, Shewart originally had only three steps, first in a line and later in a circle - Specification, Production, Inspection – known as the Shewhart cycle.

A quality engineer named W. Edwards Deming edited Shewhart’s book in 1930. Using these learnings, Deming adopted and evolved Shewart’s model. Eventually, Deming became famous in Japan for teaching the Japanese quality control tools and techniques. Deming taught that we should think about change and improvement like a scientific experiment as a way of testing, and developing your understanding of the process. In this way, you begin start critically thinking through the result or improvement. The result of Deming's work significantly improved product quality in Japan and resulted in the evolution of Plan, Do, Check, Adjust (also known as the Deming Cycle) as we know it today.

PDCA can apply to the macro as much as it does the micro. This allows the tool to be used for Hoshin or policy deployment at a strategic level, to be used as value stream implementation, to support organisational change processes, to facilitate training or the smallest process changes and improvements.

Ultimately through practice, repetition, structure and discipline, PDCA becomes habitual. We end up with way of thinking woven into the DNA of an organisation, its environment, and its people.

Defining each step of PDCA


Plan is firstly about establishing and understanding our current state - where we are right now.

Before we set off planning the next step it is critical we know the terrain we find ourselves in to begin our journey. We must grasp the current condition of our process and establish the objective or target.

Plan should be about breaking the objective down into manageable chunks. We must gain clarity of the potential obstacles and prioritise them. With this we formulate our hypothesis, in turn defining the next step. If we take this step we are predicting a particular or desired outcome. Plan should provide clarity on what we are going to do, how it will be done, and when we are going to do it.

As part of a cyclical process Plan will also incorporate component parts of the Adjust phase of the previous cycle as we will have had key learnings and reflections to inform the new planning phase.

This is an example of how PDCA applies at both the macro and micro levels.


Do is simply about executing the improvement plan. Do is about taking action - obvious, yes, but so often we find inertia in the planning phase. Do is where we test the hypothesis and run the process according to our plan.

This is often done on a small scale or short cycle to ensure feedback and learning is rapid. As the philosopher Mike Tyson once said. “Everyone has a plan until they get punched in the mouth.”

In other words: you won’t know the value of your plan until you test it in the field.


Check is about observing, measuring, understanding, and receiving confirmation on how our plan has worked versus what we predicted.

Without a check stage or metrics how will we know if the plan has been effective or not (and to what degree)? What will be checked? How will it be measured? When should we check? Who will check? What are the definitions of success or failure based on our plan?

Checking should highlight not only the overall outcome but will capture the key process metrics by which the outcome was achieved.


The adjust phase is where we stop to reflect and learn from what has happened in Plan, Do, Check. You may have seen this stage termed Act, however Adjust is perhaps a more logical fit since this component is really about learning and reflective practice.

We reflect on:

  • What has worked well?
  • What has not?
  • What we have learned from our experience?
  • What have we learned from our checks, measures, feedback and observations?

It is rare that everything goes perfectly, according to our plan. The adjust phase provides time and space to ensure we capture, standardise and sustain our gains and learnings, It allows us to understand the gaps and opportunities for further innovation or improvement. This may be an opportunity for wider sharing and communication (Yokoten) and documentation and training of the new condition or process standard.

Reap the rewards from PDCA

PDCA sounds simple in essence and can be easily glossed over, leading to poor application. But if executed well, and internalised by your teams, it is an absolute powerhouse. The meta cycle embeds intentional and deliberate practice toward improvement.

Looking to implement or enhance your PDCA approach? Talk to us today - simply book in a time that suits you via the calendar below.