What it Means to Turn the PDCA Cycle One More Time

By Jon Miller Updated on July 30th, 2017

A. It’s the first letter in the alphabet. It’s also the last letter in PDCA. Central to the scientific method, problem solving and continuous improvement, the PDCA cycle stands for Plan, Do, Check, and A is for Act, Adjust or Action. This also makes A the first step in the next PDCA cycle. And there is ALWAYS another turn of the PDCA cycle. But what exactly does it mean to Act and/or Adjust, at the nexus of completing one round of problem solving and starting the next round?

The aim of Act is to build on what one learned at phase C for Check. Some prefer PDSA with S for Study. What did we learn as we Checked / Studied our thoughts and actions during the problem solving process? What did we learn from how things turned out, from the results?

This learning in Act is not theoretical but practical. What actions can we take based on the learning? If the result was not good because actions were not sufficient to resolve the problem, the next turn of the PDCA cycle involves a) better execution of valid countermeasures, b) replacing invalid countermeasure with better ones, or c) finding additional countermeasures if the valid countermeasures were inadequate. Simply put, keep working the plan, or come up with a better plan. This should be intuitive to anyone who doesn’t enjoy the option of simply giving up and walking away from the problem.

People on the long road of continuous  improvement can get tripped up on what it means to turn the PDCA cycle one more time when the problem solving was successful. Most commonly, we look for other opportunities to incorporate the effective improvements. We may call it best practice sharing, knowledge management or horizontal deployment a.k.a. yokoten in the lean lingo. We say that we plan new improvements based on what we learned. In reality, we stop turning the PDCA cycle and switch to  DDDD. It becomes a project to implement what has been proven effective, to transplant good ideas in other environments, to create play books and to deploy globally. When these other environments are ready, Do-Do-Do-Do can work out well. Most often, this approach disappoints.

What it means to turn the PDCA cycle one more time after a successful round of improvement is to keep learning about ourselves. This requires that we look deeper into the cracks in our processes. It requires that we keep asking.

Take any problem solving exercise in which your root cause analysis has identified actionable countermeasures, and keep asking. Why did the welding robot from Taiichi Ohno’s classic example break down? Because no filter, so pump intake clogged resulting in  lack of lubricant flow, overloading the circuit. We can make oil flow visible and add filter replacement to our standard work. But why did we not have visibility of good operating conditions, such as oil level, oil flow, running temperature, circuit load? How did we not grasp that lack of filtration will result in clogged pipes? For what reasons, if we did have knowledge of how the equipment operates, did we allow ourselves to neglect basic maintenance? Was this a case of a specific machine being overlooked? What if any conditions, such as material, process method, machine operator or working environment have changed? How do we treat other similar machines? Where does this one example teach us about our general biases, blindspots and ignorance of basic process parameters?

The value from these additional turns of the PDCA cycle correlates with how persistently we keep asking. Each turn of the PDCA cycle lets us peer deeper into the cracks in our processes where systemic root causes hide. The A step of PDCA is not just, “Try again if you failed and yokoten if you succeeded”. It is not just, “Where else can we apply this solution?” Rather, it is a chance for us to more honestly grasp where and how we are failing to understand our processes well enough to consistently serve our customers, respect our people and generate a profit.

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