Which Quality Approach Is Best? Lean or Six Sigma?

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Lean is a way of thinking about quality, your employees, and how you use your resources to deliver your product or service to your customers in the smoothest, most predictable, and easiest way.  Six Sigma, on the other hand, is a process model used to separate common cause variation from special cause variation in order to reduce such variation, which, in turn, improves your process performance.

So, which do you use? Lean? Or, Six Sigma?

When Do You Use Lean?

Lean thinking can be used to reduce obvious waste.  What waste is obvious?  There are eight common wastes that are the most obvious and, therefore, are the easiest to remove from your system.  These are the “low hanging fruit” on your quality tree. Lean can be rolled out relatively easily and implemented company-wide.

Lean is a good starting point for companies looking to build a new quality system.  Lean is fast — small projects can be completed in days, or even hours.  Most Lean projects require little investment beyond people to implement the project.  You can use your regular employees on the project, giving them a little bit of Lean training to get started.

When Do You Use Six Sigma?

Six Sigma is best for problems where the solution is not obvious.  Six Sigma is a five-step process model:

• Design,
• Measure,
• Analyze,
• Improve, and
• Control.

The DMAIC model is how scientists solve problems.  They collect data, apply statistical analysis, and isolate the problem.  Then, they analyze the data until they find correlations, test possible solutions, and solve the problem.

Some Six Sigma projects can take as few as three months, while others require 12 months or more to complete.  Six Sigma requires technical experts (“black belts“) trained in the tools, statistics, and solving problems.  Six Sigma works best on isolated problems and can take years to implement company-wide.

Lean can be used at any point in time but is, perhaps, best used to implement a quality culture of continuous improvement.  Lean is a great starting point for building a quality system, since it’s easy to get started, projects are quick, and results can be obtained fast.

Six Sigma is better after a quality program is under way and employees have become accustomed to improvement.  Six Sigma is better at large-scale, expensive problems that you can collect a lot of data around.  Six Sigma is a mature quality approach that requires discipline, trained individuals, and big problems.

My suggestion is to start with Lean and build an improvement culture.  Then, after years of Lean training, implementing lean projects, and resolving the more obvious wastes in your organization, you’ll be ready for a more mature program like Six Sigma.  Some have now started to call this “Lean and Six Sigma”.

So, it needn’t be a case of “either…or”. Instead, it may be a case of the whole being greater than the sum of the parts. Lean and Six Sigma, apart from one another, are very good quality improvement tools. Together, Lean and Six Sigma are great! (Sort of a yin-and-yang, I suppose.)

Try “Lean and Six Sigma”. Let us know how well it works for you.