Lean Sigma = Lean Plus Six Sigma or Six Sigma With Just a Little Lean?


plus minusI had a conversation recently with a healthcare quality leader about her excitement about Lean.

She said that she wanted to learn more about Lean and wanted to get certified.

She then added, “I thought I'd get Lean Sigma certified, because then I'm getting both [Lean and Six Sigma].”

Here's what I told her:

I told her that instead of getting “two methodologies for the price of one” that she'd likely get a lot of Six Sigma along with a very watered down version of Lean.

This was very eye opening to her.

As I've written about before, this discussion about the merits of “Lean Sigma” has nothing to do with the merits of Six Sigma. The rigorous statistical methods of Six Sigma are certainly valid and can be quite useful… keeping in mind that Toyota, if you care about them as an example, doesn't do formal Six Sigma. They use the “7 basic QI tools” that form some of the foundations of Six Sigma, but they don't formally train or designate “belts.” I think this is a very practical approach that serves many organizations well, including in healthcare.

I recommended that, if she was very interested in Lean, she should get training (and possibly certification) on just Lean (from people like ThedaCare, HPP/Belmont, Virginia Mason, University of Michigan, or other reputable sources). Whether it's one day, two days, or an entire week (or more), there's enough to learn about Lean principles and methods to fill that time with lots of great learning. And, even with a week of education, that's probably just scratching the surface about the really important things – culture, engaging people, Lean leadership, etc.

If she went and did a “Lean Sigma” class, the focus would likely be very much on Six Sigma, with “Lean” being covered in a very superficial way, such as mainly learning about 5S and a few waste reduction methods – it would be a tools-driven explanation of Lean.

Here's the curriculum that's posted online for a typical “Lean Sigma” program. It's mostly Six Sigma.

Click on the image for a bigger picture:

lean sigma


Here's what I'd recommend to her and others:

1) Start with Lean — get education and experience with a wider variety of Lean methods and concepts. Spread this knowledge and practice to everyone.

2) Use Six Sigma where appropriate – getting specific Six Sigma training as needed and having a few experts use this approach where needed.

When I was at Honeywell back in 2004, I went through a four-week Black Belt-style course that focused exclusively on Lean (getting certified after doing a project that I was mentored on). Honeywell, of course, had a separate four-week Six Sigma Black Belt course and certification.

Their approach to “Lean Sigma” (they called it “Six Sigma Plus,” which irked me) was equal parts Lean and Six Sigma.

We need to make sure that one plus one equals two… with Lean Sigma, it seems that it actually equals 1.2, not 2.

Over the past eight years, I can't tell you how many organizations have told me that they started with Six Sigma (thanks to the influence of GE Healthcare), but they wish they had started with Lean first… that Six Sigma is something that could have been added later, as much of the waste and many of the problems in healthcare can be fixed without the rigor of Six Sigma — and Lean can be quite rigorous in its own right…

If she wants Lean and Six Sigma training… I really think she needs to do both separately. Otherwise, she'll get a very watered down view of Lean that might not serve her or her organization very well.

I'm sure some of you have differing views on this – what do you think?

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Mark Graban
Mark Graban is an internationally-recognized consultant, author, and professional speaker, and podcaster with experience in healthcare, manufacturing, and startups. Mark's new book is The Mistakes That Make Us: Cultivating a Culture of Learning and Innovation. He is also the author of Measures of Success: React Less, Lead Better, Improve More, the Shingo Award-winning books Lean Hospitals and Healthcare Kaizen, and the anthology Practicing Lean. Mark is also a Senior Advisor to the technology company KaiNexus.


  1. Hi Mark

    Great post as usual. I completely agree with you description of the situation. I have only recently started studying six sigma but I have worked many years in lean, TPM etc. The lean portion of the six sigma course is extremely interesting but mainly due to my mentor being the teacher and his depth of knowledge. Six sigma is a fantastic rigorous system but fundamentally its focus on variation reduction means that it cannot be the only thing an organisation uses to become better.

  2. From a friend on Facebook:

    In fairness — this is the Six Sigma training … the balance i think are foundational to both. But overall, i agree with you. The issue as I see it is that Six Sigma is easier to develop classroom material for, and I would also argue, requires less practical experience to teach. Lean doesn’t set up as well for classroom training (though clearly some is required) and it is more effective to ‘learn by doing’ in a facilitated project.

    What we found at GE, after studying six sigma implementations for 15 years, was that the DMA of Six Sigma is fantastic when you have unknown sources of variation. When variation is known (e.g. maybe we shouldn’t have two successive manufacturing steps located on separate sides of the plant), DMA is overkill. Finally, Six Sigma is really weak on IC …. and offers no real practical guidance on how to improve and control variability — -Six Sigma should simple reduce to DMA.

    • I’m not sure why “mistake proofing” and “5 whys” are claimed as Six Sigma methods in the image when those clearly have their origins in Lean / TPS. I had missed that at first glance.

      • Mark,

        Great job! I’ve been talking about this for years. Actually, there are lean concepts, six sigma concepts, and what I call ‘enabling’ concepts (general project management and problem solving concepts). The ‘mud’ in the water is that many ‘disciplines’ try to claim them as their own, when they are really neither. Keep up the good fight!


        • There’s a lot of overlap. For example, SPC charts are often used in Lean environments (even in my GM “barely Lean” days in 1995, we had SPC charts). That’s claimed as part of Six Sigma because it’s statistical. Fair enough. But using a control chart doesn’t mean you are “doing Six Sigma.” I saw someone recently claim that using a histogram meant “you’re now doing Six Sigma.” Good grief.

          We can use statistical methods without falling into the trap of getting everyone a “belt.”

  3. From Twitter… I agree with this sentiment that Lean and Six Sigma can work together, but that doesn’t make it “Lean Sigma”

    Kevin Clay -@SSDSI

    @MarkGraban This is a great blog! We avoid the term Lean Six Sigma. There is benefit to learning each separately as they work well together.

  4. A question for those who have gone through Lean Sigma training – what percentage of the classroom time was spent on Lean topics?

    I’ve heard estimates of anywhere from 10 to 20%.

  5. I’ve been through some really good training programs in both Lean and “Lean Six Sigma”, which as Mark described, is mostly Six Sigma with some lean tools thrown in occasionally. The LSS training was a great experience for sure, but it was 90% focused on delivering projects via the DMAIC model, which is fantastic if the improvement strategy of the organization is project-centric and “belt”-led. The same statement would apply to other project-centric/expert-led models such as Kaizen Events, GE Work-Out, etc.: they are great if your strategy is all about delivering improvement projects, as opposed to a strategy of building continuous improvement habits.

    However, I think most LSS training programs are better suited for specialists than the vast majority of operational leaders. If a nursing supervisor or production manager wants to get started on a path to becoming a lean leader, I would recommend focusing on building daily improvement habits, which requires way more practice and coaching than classroom time.

  6. Great post and responses. My main arguement with six sigma is its lack of respect for people as i understand it from the TPS model. It is almost completely hierachrical and creates it’s own Top- Down infrastructure with some input from the front line. Upper management is drawn to thier approach because it is familiar to them. In healthcare LEAN is the best approach. LEAN is culture change. LSS and six sigma do not include a culture change at the grass roots level at all. It does not create a learning organization nor continuous improvement. I also hate ( yes hate) the type of teachings that say, lean is for speed and six sigma is for quality!!!In my opinion they generally do not understand or have the patience to rigourously apply Lean and so fall back on the familiar dysfunctional way of working. To be clear aix sigma has its merits and for control of variability it is great. Again, it lacks respect for people. Compare A3 methodology versus DIMIAC: one is strictured towards not only problem solving but development of people and the other is a controlled PM tool designed to be executed by “experts”

    • Thanks for the comment, Marlon. I also really get annoyed by the falsehood that says “Lean is for speed and Six Sigma is for quality.”

      While Six Sigma does seem to be an expert-driven methodology, I don’t think it inherently goes against the Toyota/Lean “respect for people” principle. It’s just not addressed in the Six Sigma BOK, nor are many of the other cultural and management aspects of Lean addressed there, either.

      Right or wrong, I see Six Sigma as a problem solving approach and a project methodology… not a holistic culture and management system I would want to adopt.

  7. Great advice, Mark. In healthcare, I find that people often don’t even agree on definitions. Pre-Op:
    “patient ready” is “I’m done with my work/patient gowned+ IV started+labs drawn”,
    “patient ready” is “ready to roll/ labs cleared+site marked+consents + H&P updated and signed”
    Some basic observation can surface this issue with little formalized tools training of any kind.
    Are you responsible for just a task, or a deliverable ready for a customer “pull”?

    I tell people in healthcare “When you get to 4 sigma, you need 6 sigma.” I just hope that healthcare is ready for 6S by the time I am the patient on a ventilator.

  8. Mark, I’m pleased you posted this. South Africans frequently ask me whether they need Lean, Six Sigma or a marriage of the two. A good starting point is to understand what problem you are trying to solve, then bring in the right tool and methodology to work at it. Many have found Lean to work particularly well with ‘low-hanging fruit’ problems – and while an organisation has plenty of those to go around, Lean will do them just fine. But tackling systemic problems could require more tools, and at this point it may be worth exploring other methodologies to support this.


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