First off, I’m not trying to dredge up a “Lean vs. Six Sigma” battle here. I’m not “anti-Six Sigma.” I’m not a huge proponent of the methodology and I don’t practice Six Sigma personally, but I see a place for a structured statistical quality improvement methodology to help solve certain complex problems.
What I *do* take issue with is the “Lean Six Sigma” community consistently misrepresenting Lean. This needs to stop.
The “Lean Six Sigma” crowd seems to consist of a lot of Six Sigma “black belts” who have also adopted Lean. As an aside, you rarely see Lean practitioners rushing to add Six Sigma to their approach. There can be multiple interpretations of that, depending on your perspective. Now, organizationally, many hospitals use Lean first and then layer Six Sigma on top of that to help solve particularly sticky problems. That approach is reasonable, but what I mean is that fewer “Lean professionals” add Six Sigma to their personal repertoire than vice versa.
I believe that Lean and Six Sigma are two similar, but different, yet complementary things. I don’t consider “Lean Sigma” or “Lean Six Sigma” to be a single comprehensive methodology. And I think that’s more than just nitpicking over semantics.
“Lean Six Sigma” often gets explained like this (a direct quote from one communication I received recently):
- Lean is about Process Speed, Efficiency, and Agility, Improving the flow of goods and services with a standard and visible workplace
- Six Sigma is About Process Quality, Reducing Defects, and Variation, Improving the process to meet customer requirements
It’s always a split of “lean is about speed and six sigma is about quality.”
This is factually incorrect, this notion that Lean is just about speed. It’s incorrect to say that Lean doesn’t address quality, both directly (through methods like error proofing and root cause problem solving) and indirectly (the improvements in quality that tend to come with better flow).
Look at the core, basic, fundamental roots of Lean, the Toyota Production System.
Illustrated as the “Toyota House,” it has two pillars:
- just-in-time (flow)
- jidoka (quality at the source)
With the rich history of Toyota/Lean methods for quality, such as poke yoke (mistake proofing) and the history of the pre-automotive era Toyota weaving loom that automatically stopped when the thread broke (read the history of jidoka on the Toyota website), you can’t deny that Lean is about quality AND flow. They go hand in hand. Improving quality leads to better flow, better flow (through less batching) leads to better quality.
As one of the original Six Sigma gurus, Thomas Pyzdek, said on twitter:
Quality is a result. Lean and Six Sigma are about identifying the critical drivers and root causes of quality results. It’s not either/or, it’s and.
Agreed, it’s not “either or,” and when Lean Six Sigma people say Lean isn’t about quality, they look silly and they do their followers no favors.
Does Six Sigma help improve quality? Well sure. Does Toyota use Six Sigma? No. Toyota uses the 7 Basic Q.C. Tools, which are:
- The cause-and-effect or Ishikawa diagram (fishbone)
- The check sheet
- The control chart
- The histogram
- The Pareto chart
- The scatter diagram
- Stratification (alternately flow chart or run chart)
Many of these tools and methods pre-date Six Sigma. They are included in even the most basic Green Belt education. Yet, they can be used without the formal Six Sigma methodology, as Toyota and many leading “Lean Hospitals” would practice.
I’ve reading a book that was published earlier this year titled, Lean Six Sigma for Hospitals: Simple Steps to Fast, Affordable, and Flawless Healthcare. Sadly, the introduction to the book mentions nothing about Lean as a quality improvement method, nor does it talk about Lean as a management system. It’s all tools and projects.
The most disturbing passage comes in the discussion of the “types of waste” — a concept that comes from the Lean methodology. The book seems to again imply that Six Sigma is what’s needed for quality, as the first six types of waste (including overproduction, waiting, etc.) are the only things Lean addresses:
If the author doesn’t mean to say that Lean doesn’t impact quality, the section is poorly written and confusing.
I’m not sure where the “Lean Six Sigma” crowd got off the rails on their description of Lean. Saying or implying that Lean isn’t a quality improvement methodology is L.A.M.E. — Lean As Misguidedly Explained. It’s necessary to speak out, as too many are spreading the wrong message about Lean.
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