My teenage education was (maybe) enhanced by substantial doses of Monty Python. Occasionally, I discover a lean metaphor somewhere within their body of work. One of my absolute favorite scenes is from the movie, Monty Python and the Holy Grail. The three-minute scene goes by two names: “The Bridge of Death” or “The Three Questions.”

I was a 30-year-old quality project manager on a continuous metal processing line. We coated metal for a broad range of consumer and industrial products. Just like many metal-processing facilities, particularly back then, we used a bunch of processes involving chemistry of varying evilness for a range of reasons.

Many years ago, I was flipping through stations on the radio and came across a talk show. I don’t remember the topic of discussion, but something the host said stuck with me.

“Scientists,” the host blustered (and I paraphrase), “are 95-percent confident of these results! Wow!”

The sound you’re now hearing is that of mathematicians tearing out their hair.

Six Sigma has been credited with six- or even seven-figure returns in single projects, but it has not kept the manufacturing jobs of its principal exponents—Motorola, General Electric, and Maytag—in the United States. Henry Ford, on the other hand, proved that lean manufacturing can make almost any job sufficiently productive to pay high wages to an American worker. Why, then, does Six Sigma deliver outstanding results in some applications and fail miserably in others?

After my last column citing some really bizarre flaws in how our brains perceive reality, I thought I might cover some flaws in logic that are applicable in the world of quality. So, basically, even if our brains are working correctly, we can still send our Black Belts off on false trails trying to solve problems, thus offering more proof (as if we need it) for Voltaire’s observation that “common sense is quite rare.”

I got one of those mass e-mails the other day, the ones with inspirational stories promising good luck and eternal salvation, provided you forward it to 10 people immediately. I chose to delete it and take my chances with the Almighty, betting that He was not really a party to an agreement linking my e-mail outbox to a ticket to heaven.

Measurement error is ubiquitous. As a result, over the past 250 years, different areas of science and engineering have come up with many different ways to deal with the problem. One approach to the problem off measurement error was developed during the 1960s within General Motors. Throughout the years it was modified and revised, until in 1989, it was turned over to the Automotive Industry Action Group (AIAG) within the automotive division of the American Society for Quality Control (as the ASQ was then called).

A friend recently returned from a visit to China; his company had been acquired by a Chinese organization and he had gone there as part of the mutual due diligence. Not only did he come back impressed by their lower manufacturing costs but also with their technological advancements. While we in the United States hear of low quality standards of Chinese products, he was awed by the their adoption of current lean measures and Six Sigma, or a combination of the two as lean Six Sigma.