With Labor Day coming around, here’s an article to celebrate the folks who usually get blamed for the quality problems.

Not surprisingly, when people first learn about lean’s seven wastes, the one they find most relatable is defects. They might not immediately grasp the concept of overproduction or the other wastes, like storage or transportation, that it creates, but defects are different—they’re personal.

Who hasn’t made a mistake in their work that’s resulted in scrap or rework—or perhaps an angry word from the customer? As a factory manager, when I first learned about mistake-proofing, I felt like I’d just uncovered a treasure trove of inadvertent human errors that could be trapped before they created defects, or at least before the defects could be passed on to the next process. Poka-yoke, a Japanese word meaning “without mistake,” quickly became common lingo in my factory. Workers, frustrated by being told to “be more careful,” began inventing inexpensive devices—we called them poka-yokes—to stop mistakes in their tracks.

Through the power of mistake-proofing, employee frustration with mistakes was transformed to something completely different, recasting frontline employees as problem-solvers rather than problem-causers. No more ineffective warning reminders or disrespectful accusations. Once we deployed the poka-yoke method, defects arising from mistakes plummeted, production flow accelerated, and morale shot through the roof. For me, the morale thing was the most amazing aspect of poka-yoke—uncovering once-hidden gold nuggets to make the job “easier, better, faster, and cheaper.”

Because of its effect on creativity and human development, mistake-proofing has always been my favorite countermeasure. We’re not admonishing workers to “do it right the first time,” as Philip Crosby’s famous quote (taken out of context) suggested. The magic of poka-yoke, as expressed by Shigeo Shingo, is in its humanism:

“Errors will not be eliminated as long as humans remain human. But errors need not turn into defects if they are discovered and corrected at once. Defects arise when errors are allowed to reach the customer.”

However, even Shingo’s comments can be taken out of context. The second sentence from the above quote was thrown in my face recently by a client. I noticed they used the word poka-yoke as a general term to mean implemented countermeasure. When I inquired why, I was told, “Because Shigeo Shingo says so: Defects arise when errors are allowed to reach the customer.”

“What about defects caused by storage or transportation or maybe by a machine hiccup?” I asked the plant manager. “Are they mistakes, too?”

His response: “Well, someone made a mistake, and anyway we caught it in time.”

The significance here was in the lack of curiosity to trace a defect to its source, which isn’t always human error. For example, is the work not standardized, or the worker not trained to confirm quality, or the plant layout a maze? Or is a machine not capable, or is excess stock on hand stored everywhere? At this factory, these possibilities (all observed) were apparently extraneous as long as the defect could be trapped before it was “allowed to reach the customer.”

What’s worse, by relating all trapped defects to mistake-proofing they inadvertently disrespected frontline employees, sustaining the apparently inextricable connection between frontline employees and defects.

So, here’s a Labor Day question for you: Are your frontline employees problem-solvers or scapegoats? Enjoy the long weekend.

And more

Want to build a culture of respect for people at your site? Take a free test drive of The Respect for People Road Map or join our next cohort, starting Sept. 11, 2025.

Also reserve now for the 21st Northeast Lean Conference in Manchester, New Hampshire, Oct. 27–28, 2025. Arrive on Sunday and enjoy the foliage before recharging your lean batteries.

Published Aug. 18, 2025, in the Old Lean Dude blog.