Lean and Six Sigma: PDCA and DMAIC Comparison

Integrating or reconciling the PDCA framework from Lean and DMAICfrom Six Sigma is the topic of this post.

Since both methodologies and frameworks share a common history, it is no surprise that integrating their respective frameworks was not difficult to do.

Below is my attempt at exactly that. Below the PDCA and DMAIC comparison chart, I’ll explain some big and some subtle differences.

Now, on to some differences between DMAIC and PDCA:

Differences Between PDCA and DMAIC

Visually, PDCA has 4 steps, while DMAIC has 5. But, it’s not just 5 steps, but 5 steps and tollgates in between each phase. A tollgate is where the project team or team leader presents his or her findings in the current phase and the steering committee will either approve the project to move to the next phase or not.

A big difference between PDCA and DMAIC is the corporate infrastructure required. Six Sigma and the DMAIC methodology in which its work is carried out, requires a steering committee, tollgates, a champion, and a project sponsor.

While all those might be good, given the right context, the organizational burden on a company is real because it requires up-front investment of time, resources, and attention.

On the other hand, the PDCA framework of Lean is completed many, many times without much hoopla or fanfare. Indeed, the PDCA framework of Lean allows for the involvement of everybody, whereas DMAIC of Six Sigma requires specialized and trained people, often called Black Belts, Green Belts, or Master Black Belts.

There are no belts in Lean; the mindset of Lean and the tools it uses to carry out its work is highly accessible to everybody – no belt required. No barriers to entry or barriers to participate, just some training, ongoing training, and a lot of hands-on doing.

So, in our compare and contrast of PDCA versus DMAIC, they are quite similar, except for the organizational infrastructure required in Six Sigma.

Because of the differences I note above, the benefits of Lean and the PDCA framework is often heralded because of its speed and velocity. This is true, because there is no organizational overhead and improvements are made – many, many small improvements – daily.

It’s Your Turn

Given the context and the company and the needs of the organization, consider the differences and the commonalities between Lean and Six Sigma. Where one might meet your needs, the other might not be right for you. You decide.

Lean Six Sigma: Elements of DEFINE

The first phase in the Six Sigma Define-Measure-Analyze-Improve-Control (DMAIC) Methodology is Define.

During the Define phase, a team and its sponsors reach agreement on what the project is and what it should accomplish.

The main work in the Define phase is for the project team to complete an analysis of what the project should accomplish and confirm understanding with the sponsor(s). They should agree on the problem, which customers are affected, and how the current process or outcomes fail to meet their customers’ needs.

Some tools that help in this phase are the following (suggestions only, not mandatory):

• Voice of the Customer
• Affinity Diagram
• Critical-To-Quality (CTQ)
• Stakeholder Analysis
• Kano Model (Kano Analysis)

The outcome of the Define phase are typically the following:

• A clear statement of the intended improvement (Project Charter)
• A high-level map of the Processes (SIPOC)
• Current Performance of the process, typically displayed through a run chart.
• An understanding of the project’s link to corporate strategy (hoshin kanri) and its contribution to (Return on Invested Capital (ROIC)

The above is a standard template for the elements of the Define phase in Six Sigma.

Lean and Six Sigma: A Common History

Both the Toyota Production System (Lean) and Six Sigma approaches owe their origins to a common body of work. Statistical Process Control (SPC), developed by American engineer and statistician Walter A Shewart, is one of the foundations of lean. It is also the basis for much of the Six Sigma methodology. The other lean foundation, Total Quality Control, was developed by Dr. W. Edwards Deming and applied by him in both the United States and Japan.

These two founding themes were embraced by Taichi Ohno, who is broadly acknowledged as the father of the Toyota Production System. Shigeo Shingo—who is well known for taking concepts of zero defect production, Single Minute Exchange of Die (SMED) and Toyota Production System to a broader audience.

Excited by the simplicity and elegance of process control and the need to manage production efficiently, and driven by the need in postwar Japan to fully realize the “less is more” principle, Toyota developed TPS as a way to achieve previously unheard of levels of productivity, quality, and flexibility with minimal investment.

Aside from the shared history of both Lean and Six Sigma, both also share a common philosophy: Lean and Six Sigma both believe in systematically solving the problems that affect the customer.

Book Review: The Toyota Mindset

The Toyota Mindset was written by Yoshihito Wakamatsu who worked directly under Taiichi Ohno. The contents of this book is a documentation of his interactions with Taiichi Ohno – what he said, how he said it, and the “why” behind many of the well-known methods in the Toyota Production System.

His book is organized into 10 chapters, each of which he calls “Commandments”, claiming that Taiichi Ohno lived by 10 main ideas and makes a caveat that the word “commandment” are the author’s, not Taiichi Ohno’s.

Below are the 10 main ideas Wakamatsu claims Taiichi Ohno lived by:

1. Wastes hide, so start by disclosing all of your mistakes
2. Discover the truth beyond your understanding
3. Increasing production while limiting the number of workers is the only way to gain true success
4. Act on problems right away and do not procastinate
5. Don’t feel satisfied by saying “I finished the job”; go beyond that and say ”I can do more”
6. Add “Appropriate Timing” to “Appropriate Method” in problem solving
7. Believe in “I can” and question “I can’t”
8. The key to achieving progress is to never give up
9. Don’t do work at an average pace; the shortest way is always the easiest
10. Change yourself first, if you want to change someone else