The Plan-Do-Study-Act Cycle

How much data you need to collect is another difficult question. Hopefully, as you collect and analyze information, you will begin to develop hypotheses about what actions should be taken. At this point, you need to develop a plan. Your analysis may have positioned you to have extreme confidence in the plan, or you may be at the level of exploring hypotheses. If you have not developed even a reasonable hypothesis, you need to continue looking at information. If this has gone on for a long time, and if you are working on a very important problem, you should seek help from someone more experienced in this process. It is important not to act unless your planning 

When you complete your study, you can proceed to the act phase. In this phase, plans found to be effective are implemented on a wider scale. The cycle repeats again and again to generate continuous improvaneuL If the smdy phase shows that your plan is not effective or that it needs modification, you return to the plan phase. 

When we began to apply this process to safety, we already had extensive experience with successful application of the PDSA cycle for improving manufacturing and service processes. It was logical that the model would work for safety improvement. The first challenge is always measurement. Planning requires information about the system. To the extent that you can develop information that helps you understand how the system works, your plan will be successful. It is not how much data you have but whether you have measured the proper thing. This is not trivial. All too often businesses measure what is easy or what is obvious. 

After a combined 60 years of managing and observing the operation of business, we know it is not quite so simple. Part, but not all, of the problem lies in the two corollaries that we would add  

What gets measured is what gets done  

---

Another problem-solving methodology popular with lean thinkers is the PDCA problem-solving loop. PDCA (plan-do-check-act) is an iterative four-step problem-solving process typically used in business process improvement. It is also known as the Demlng cycle, Shewhart cycle, Deming wheel, or Plan-Do-Study-Act. 

PDCA (plan—do—check—act or plan—do—check—adjust) is an iterative four-step management method used in business for the control and continuous improvement of processes and products. It is also known as the Demingcirck/cycle/wheel, Shewhart cycle, control circle/cycle, or plan—do—study—act. 

Deming explained that the process for improving a system is the cycle of plan-do-study-act depicted in Figure 3.1. He CTedits this formula for process improvement to his mentor, Walter Shewhart, and calls it the Shewhart cycle. Others have called it the Deming cycle or the PDSA cycle. 

Improvement plans should be developed using the Shewhart cycle of plan-do-study-act. 

---