In Lean Six Sigma, we strive to reduce variation and eliminate defects—but even the best-designed processes are still run by humans. And humans, no matter how skilled, make mistakes. That’s where Poka-Yoke, or mistake-proofing, comes in. Originally developed by Shigeo Shingo at Toyota, Poka-Yoke (which translates to “error prevention”) is about designing processes so that mistakes either can’t happen—or if they do, they’re detected and corrected immediately. In other words, i
