Jun 2 2026
Some Hazardous Ideas | Don Wheeler | Quality Digest
On 5/28/2026, in QualityDigest, Donald J. Wheeler bashed “hazardous ideas” from a list he received from Allen Scott. Allen is a frequent contradictor of mine on LinkedIn, and I welcome his comments whenever they go beyond calling my work “garbage.” Although Wheeler does not name me as the originator or a propagator of these “hazardous ideas,” I’ll take the bait and respond about the ones I actually support.
The “hazardous ideas” are all about SPC, which, to Wheeler, boils down to XmR charts, relabeled “Process Behavior Charts.” SPC receives more attention than it should, given that it is used in practice almost exclusively for ceremonial purposes. The most dramatic quality problems of the past 25 years were tread separation on Firestone tires mounted on Ford Explorers in 2001, Toyota’s unintended acceleration in 2010, and Boeing 737 MAX crashes in 2019. None of them was related to or solved with SPC.
Google’s ngram viewer shows the relative frequency of quality-related key phrases in English-language books peaking in the 1980s and 90s and waning since. “Quality Control” is now down to its 1940 level. All the other phrases followed similar trajectories, peaking later, the latest one being “Six Sigma” in the late 2000s. Oddly, the only one with any uptick since 2010 is “SPC,” and it dominates all the others.

The overall decline in interest in the field is worrisome, given that there is no evidence that the quality of manufactured goods has been improving since the turn of the century. The JD Power and Associates Initial Quality Surveys of car brands show massive increases in customer complaints, and the life of household appliances has been getting shorter. If the quality of manufactured goods is deteriorating, we should see more publications on fixing it rather than fewer, and they should focus on approaches that address today’s problems with today’s technology.
So, to contribute further to the excessive attention to SPC, let’s run through some of the ideas Wheeler deems hazardous.

Aug 9 2026
Houses of TPS
The “House of TPS,” is popular in the US and Europe as a summary of the Toyota Production System. We trace its origins and review its design and components in a 2007 version from Toyota Europe. Nigel Thurlow posted in on LinkedIn and says he was in the room when his Toyota colleagues drew it. We explore why the Greek temple theme was adopted, and suggest it may have been to make TPS appear less foreign to Americans.
Once stripped of the temple, it is a stack diagram, and we review the content of the boxes from bottom to top. While popular and widely copied in multiple variants by American consultants, the only Houses of TPS I could find in Japanese are translations of Jeffrey Liker’s.
While the House of TPS resonates with Americas, even the version developed within Toyota fails to provide more than a list of keywords, while leaving out key elements. The best it can do is motivate the reader to dig deeper.
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By Michel Baudin • Management 0 • Tags: House of Lean, House of TPS, Lean, Toyota, Toyota Production System, TPS