Lean Six Sigma is Not Lean

Lean Six Sigma is not Lean. It is Six Sigma, but one that is more “Lean” than just regular “Six Sigma.” In the English language the adjective (Lean) modifies the noun or subject word (Six Sigma). So Lean Six Sigma is technically not Lean at all, but a form of Six Sigma that has less fat in it than regular Six Sigma.

Just like “diet soda” is not a form of diet but a form of soda.

“Six Sigma Lean” on the other hand, is redundant since Lean manufacturing already implies Six Sigma, in that the development of Lean manufacturing at Toyota comes directly from Deming’s work on statistical quality control. Although they are not so popular elsewhere, QC Circles are active in Japanese companies as well as in Toyota. The whole “QC Story” approach to work team kaizen based on the scientific method is implied in Lean manufacturing. So I think that Six Sigma Lean is redundant.

Don’t even get me started with Lean Sigma.

If there were a “soda diet” that made you thin by drinking just Cola, that might work, but I think this would just make you sick.

So what do we call the intentional merging of Lean and Six Sigma values, skills and tools?


  1. Mark Graban

    February 21, 2007 - 7:23 pm

    I had always heard that Toyota doesn’t do “six sigma” but they might use some six sigma statistical tools. They definitely don’t have black belts running around, right?

  2. Ron

    February 21, 2007 - 7:25 pm

    Well, gosh I feel silly since I named my blog LSS Academy! Seriously though, I am not a big fan of merging the methodologies as I think they are meant to serve different issues. Six Sigma is about killing variation and reducing defects. Six Sigma is full of heavy stastistical tools (hypothesis testing, multiple regression, response surface optimization, etc.) that target variation in a major way. I wont tell you or this audience about what Lean does for obvious reasons. I do think Nokia is on the right track when they call it “Smart Manufacturing” since they have Lean, Six Sigma, etc. under the one Smart umbrella. My current company simply calls it all “Continuous Improvement Process”. Our “house” has two pillars. One is Lean and one is Six Sigma. That works for us.

  3. Anonymous

    February 22, 2007 - 2:36 am

    Thank you for the interesting English lesson let’s call it Kaizen

  4. Mike Wroblewski

    February 22, 2007 - 6:44 am

    Good post Jon. As a lean practitioner with a Six Sigma Black Belt, I agree. I would only change one point that the scientific method is more than implied in Lean Manufacturing, it is the foundation of the problem solving approach.
    What do I call the intentional merging of Lean and Six Sigma values, skills and tools? Marketing.

  5. Preston

    February 22, 2007 - 11:39 am

    “What do I call the intentional merging of Lean and Six Sigma values, skills and tools? Marketing.”
    Well said!

  6. Jon Miller

    February 22, 2007 - 3:57 pm

    Lean is good. Six Sigma is good. Marketing is good if it means communicating about a good product or service in order to encourage people to buy or use the product or service. It’s all kaizen. It’s all good.

  7. Rajdeep

    February 23, 2007 - 12:40 am

    We can call it another way for consultants to make more money by rehashing and creating a new acronym and also another addition in the CVs of dudes of process improvement to differentiate themselves from the pack by saying “I am not a Six Sigma guy, I am a Lean Six Sigma guy!!”.
    I think the whole point is lost when people think of these approaches as tools and try to link them up or talk about combining tools.
    The intention of both Six Sigma and Lean is to improve processes and create a culture of continuous improvement. However, the approach and the underlying of both are very different.
    Thinking of these as set of tools merely illustrates the lack of understanding of both Lean and Six Sigma. Anyone who says that Lean is focussed on waste reduction while Six Sigma is focussed on variation, again has not got the concept.
    In simple terms: Six Sigma is a scientific method to solving problems – more specifically, process problems. It is just that. It does change culture and makes people more data based but those are impacts of Six Sigma roll outs. Especially when you roll out dashboards with those. SS is rolled out by a team of specialized and trained people.
    It is a very powerful approach but has been made complex by people with jargon and attempts to make it more erudite by adding even more complexity in the tools.
    Also the focus on the “right approach” to solve the problems forces people to enforce usage of templates (to make it simple) and the focus then shifts completely to adherence to templates rather than the concept per se.
    Lean on the other hand, with focus on respect for people and continuous removal of waste is a wider view to improvement than just six sigma. A lot of things in Lean like gemba (which changes the work that senior management does); pull, flow and jidoka (that impact role of people on shopfloor and even accountants) and focus on muda, mura and muri have a different kind of focus on how people work and how managers create a system for working.
    Other diff. of course is that most of the changes are driven by people who are doing work.
    Lean is a more system wide approach although it works to improve processes (value streams) also.
    Lean directly affects the way we work at all levels and the way work is designed.
    For a process level problem solving, Lean uses PDCA. And Six Sigma is a more refined and much more scientific and data driven version of PDCA.
    However when you say Lean complementing Six Sigma, it basically means using the tools within lean (like VSA) and making the Six Sigma toolkit bigger. And that completely misses the point of Lean affecting the system and the process.
    I am not a Lean consultant who just wants to berate Six Sigma without understanding it. I have been a Six Sigma MBB and then moved to working on Lean. There are weaknesses in lean approach also (and people who push TOC will gladly point those out).
    Overall, the purpose of all these is the same – improvement in business. Six Sigma works more at process level. lean works at system level and process level. Six Sigma leads to culture change (possibly) but lean tries to bring that about more directly.
    In Lean organizations also we use organization wide projects or large projects that involve Six Sigma type of tools.
    But comparing Lean and Six Sigma is like comparing Calculus with “how to solve quadratic equations” OR comparing English Language with Rules of Grammar and Punctuation.
    Lastly, based on my understanding, you can apply Six Sigma tools everywhere, I feel Six Sigma would require organizations to be of a certain level of maturity (not size) before it can make sense.

  8. Ron

    February 24, 2007 - 5:44 am

    Rajdeep – Great explananation. Long, but great. I do think you are oversimplifying things a bit. As an MBB, how many SS projects did you see successfully “speed” things up? I mean trying to say y (speed) is a function of x1, x2, x3 is a bit arduous. And while it certainly can be done (OK, I admit I have seen a few SS projects attack speed and do OK) it is like using a hammer to screw in a nail.

  9. Mark Graban

    February 24, 2007 - 3:17 pm

    I saw a new buzzword yesterday (yes, from a consultant)…. “K-Sigma”
    It’s basic the Six Sigma DMAIC model with Kaizen Events.
    Yeah, I’m a consultant.

  10. Rajdeep

    February 25, 2007 - 6:25 pm

    I got some informal feedback from friends about the tone of my note and having read it again I do feel it is quite acrebic – maybe it is the food I have been eating over the Chinese New Year Holidays.
    At a personal level, I like Six Sigma approach. A lot of my personal wealth, jobs I got and respect I get is because of the experience I had as a BB and then MBB.
    But after I learnt the Lean approach from Toyota Senseis and worked on it last 2 years. I realized that they both work on a different scale.
    I do agree my previous post is trying to simplify the difference but the basic point is same – Six Sigma is a toolkit to help solve process problems and it does work well on that. Lean is much more than a set of tools.
    Apologies if my post made a blanket assumption that everybody doing Six Sigma is bad or undermined their understanding and work.

  11. Ian

    February 26, 2007 - 3:32 am

    Lean Six Sigma is about combining complementary best practice. Six Sigma reduces variation while Lean eliminates waste.
    The statistical tools used in Six Sigma have been around for years – Shewhart, Juran, Deming, Ishikawa, etc. The elements of lean management – Standard Work, Visual Controls, Accountability & Discipline – Gemba are essential lean management tools.
    Since Motorola developed a program in the late 1980’s and GE adopted it, there has been a relatively slow take-up for Six Sigma methodology. This project by project apprach to improvement is not too different to Juran’s Quality Trilogy approach developed in the 1950s.
    Compare the take up rate for Six Sigma to that of the ISO Standard which was also launched in the late 1980s. ISO certification is a must for any company doing business as evidence of a functioning Quality Management System. You see, there’s no obligation for an organisation to implement Lean Six Sigma – there is no certification stating ‘this is a Lean Six Sigma Company. It is only in the 21st century that organisations are realising the competative edge that the DMAIC & Lean approach can offer by reducing production costs. Now, these tools and techniques are no longer in the hands of gurus, specialists or consultants but are with people involved in the everyday process (Green Belts) who can select the most appropriate tool for the job.
    Unfortunately, you will have the ‘carpet baggers’ who will exploit the growing demand for these best practices and add another acronym to gain an edge. It’s people like this who give Lean & Six Sigma a bad name – creating the opportunity for detractors to say ‘it’s just the latest Quality tool’.

  12. Anonymous

    March 9, 2007 - 5:58 am

    plz go read more Lean and SS, sad to find these kind of article

  13. Calvin.K

    June 27, 2009 - 3:21 am

    Six sigma lean is definately come from lean and six sigma. They using six sigma to control on the quality and lean to focus on reduce the waste.
    Why we need both?because six sigma adding a lot of non-value added such as SPC, inspection are all non-value added and therefore lean applied to reduce the waste.
    Lean is derived mostly from the Toyota Production System, then why we dont we call TPS but lean?

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