Critical thinking does not necessarily result from using a practitioner’s toolbox framed within a formal improvement structure such as Six Sigma, lean, lean Six Sigma, or the Toyota Production System. It’s very easy to get seduced by all the fancy tools, acronyms, and Japanese terminology—and promises. I’d much rather have far fewer tools used in conjunction with critical thinking to understand variation—in one’s native language. So again, it’s time to apply critical thinking to rapid-cycle PDSA, the plan-do-study-act method for learning and improvement developed by Walter Shewhart. If you find yourself confused and frustrated in your current applications, there’s good reason.

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