What is Lean vs. Six Sigma vs. Kaizen?

Posted on January 3, 2013 | in Kaizen, Lean Tools, Lean Wastes, Motion, Quality, Waiting | by

Control Chart Example six sigma

Questions I’m asked often – by potential clients and colleagues and friends alike – center around Lean versus Six Sigma, and versus Kaizen. What are the differences between them? When would you know when to use Lean, Six Sigma, Kaizen, or something else? And my favorite…which one is best?

To give a quick answer to the last question, the best method is whichever method is appropriate for the project. What many people fail to realize is that they are all specialized tools that are used to solve specialized problems as opposed to the answer to every problem. There are scenarios where Lean principles are most appropriate, while other scenarios lend themselves to Six Sigma for their adequate solutions.

Much in the way a metric socket is different from a hammer and a power sander, Lean and Six Sigma and Kaizen are all different tools that solve different problems. When performing home improvement, you don’t pick up a hammer and say “Hokay, what can I go fix with this?” Just because you have the tool doesn’t mean you should use it.

No tool should be “picked up” until one can properly answer the question “What is the problem we are looking to solve?” Process and problem knowledge can help you identify which tool is appropriate based on that question’s answer.

What is Kaizen?

As I’ve shared before, Kaizen is more a continuous improvement mindset as opposed to being a specific tool. The Kaizen mindset uses personal creativity and ingenuity to identify problems and then develop and implement ideas to solve those problems. The key piece of the Kaizen mindset is acknowledging that everything can be improved and everything can perform better or more efficiently.


(Photo from Foodhoe Foraging)

For example, when I dine at a restaurant I typically do a mini-Kaizen improvement with condiments at the table. The problem I aim to solve is to reduce excess motion and waiting (more on this in a second) by moving condiments I know I or my dining companions will be using closer to us or verifying their containers will have sufficient supply for our consumption (I almost always request an extra ketchup bottle, based on how much I generally use). It’s a quick improvement that helps to save exertion and time (if we must wait for extra mustard before commencing eating).

Kaizen-type improvements can be as small as a single person identifying and fixing a problem, or it could be a handful of people working together to solve a problem that affects each of them in a different manner. A Kaizen event is a collection of resources (dedicated people, money, and time resources) that are pulled together to collectively build on the Kaizen mindset, typically with a targeted problem project in mind. When most folks hear “Kaizen” they think “event” and this is not always an accurate portrayal. A Kaizen event would be an example of a tool – not every problem requires a giant pre-planned Kaizen event.

What is Lean?

Lean, as a management philosophy, is focused on improving process speed and quality through reduction of process wastes. The eight Lean process wastes all consume unnecessary energy, money, and time – those investments in process wastes are not things that provide value to the customer. By reducing activities that drive up cycle times or cost money unnecessarily, processes can become more efficient and more predictable. While Lean is identified as a problem solving tool, it is itself a series of tools that help to reduce the process wastes.

Referring back to my condiments example, excess motion and waiting and are two of the Lean process wastes. I’m generally hungry if I’m at a restaurant and I want to satisfy my hunger as quickly as possible. If I have to wait on my server to bring me a missing condiment that I require for my food before eating, that further delays my hunger satisfaction. Excess motion to repeatedly reach across the table for a condiment every time I need it could be disruptive to my dining partners or is simply unnecessary exertion and can consume my time and for those whose paths and plates I’m crossing with my arm.

What is Six Sigma?

The key piece of Six Sigma is consistent output, stability, and accuracy. A process deliverable will have key characteristics that a customer would require, and Six Sigma is a tool or methodology that optimizes the consistency of those key characteristics. Six Sigma is heavily driven by statistics and measurements. The top picture in this post is an example of a control chart that measures a key characteristic from one sample to the next. Six Sigma aims to reduce output variation through the use of statistical analysis and root cause analysis. This is a very simplistic answer because Six Sigma applications are typically very complicated, but this is where the rubber meets the road.

Lean Six Sigma

How would I know when to use Lean, Six Sigma, Kaizen, or something else?

When I am presented a problem (or what is perceived to be a problem) by a client I first jump to the Kaizen mindset and ask “What is the problem we are looking to solve?” I don’t even think about Lean or Six Sigma until I get that answer.

In my personal (or professional) opinion, I believe Lean principles and the 14 principles of The Toyota Way as being the first set of tools applicable to any scenario. I’m generally starting with a problem where there is a complete lack of process standardization and optimization. We can achieve standardization and optimization with the Lean tools.

Six Sigma is a strong methodology after processes are standardized and optimized. At that point the process is looking for improved process outputs and consistent performance, and Six Sigma is an excellent suite of tools for achieving this.

Other resources on the differences in the tools:

What is Lean Six Sigma?
The Difference Between Kaizen and Six Sigma
Message Board Post – The Difference Between Kaizen and Six Sigma
Lean versus Six Sigma
Is this a Lean, Six Sigma, or Kaizen project?

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14 Responses to “What is Lean vs. Six Sigma vs. Kaizen?”

  1. Mark Graban says:

    Hey Chad – I get ese questions a lot, as well.

    While my career has been based on the Lean methodology, I recognize that there’s a role for the Six Sigma improvement methods, especially the statistical methods. To me (and to many), Lean is indeed a holistic philosophy and a management system, where Six Sigma seems to have devolved into a cost-cutting strategy.

    The diagram you show with Lean being about “speed” does a disservice to those who are learning about Lean, it’s not just oversimplifying. Lean (and the Toyota Production System) has two pillars: Just-in-Time (flow, or you could call it speed) and Jidoka (or quality at the source). Lean is BOTH speed and quality, as opposed to having a tradeoff between the two.

    Too many in the “Lean Six Sigma” world have spread a false dichotomy that Lean is about Speed and Six Sigma is for quality. Lean is, at its core, historically and practically, a quality methodology.

    Kaizen is a core part of the Lean philosophy (along with “respect for people”) if you look at the two pillars of “The Toyota Way” management approach.

    I agree wholeheartedly that starting with “what problem am I trying to solve?” is key.

    • Chad Walters says:

      Mark –

      You are absolutely right. Simply saying Lean is about speed certainly does it a disservice. Lean is definitely a quality methodology. The diagram helps me differentiate between Lean and Six Sigma even though there are a lot of crossovers. Lean focuses on efficiency, and components of efficiency include speed, optimized resource consumption, and defect reduction. For someone as long winded as I am, it helps with my elevator speech. I would never try to sell Lean as a tool for simply doing things faster. There are a lot more pieces to it.

  2. Matt Wrye says:

    Mark –

    Your comments above are right on. I would also add that lean is a management philosophy that is about delivering value for the customer. By focusing on value for the customer you can eliminate waste that ends up speeding up the process as well as improving the quality of the process and product or service. Delivering value to the customer well allows the ability to grow.

    The Six Sigma vs. Lean question is one I hear a lot too. I will not pile on. Mark, you answered it very well.

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    • Chad Walters says:

      I look at TPM as one of the Lean tools. However, when I was with The Dannon Company our manufacturing line management tool was autonomous management, which is very similar to TPM.

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  9. Jennifer says:

    Where can I go to become Lean Six Sigma Certified?

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