Lean, Six Sigma, or Lean Six Sigma?
Due to recent comments on this blog post (scroll down to view the comments section), I want to acknowledge that the definition of Lean in this post is incomplete. The goal of this post wasn't to offer definitions of Lean, Six Sigma, or any other methodology, but was rather to state that the focus of improvement efforts should be on using all the available tools, whether those be Lean or Six Sigma tools or both, to make the necessary improvements. Thank you to those who left comments and opinions. I appreciate your viewpoints and discussion on this topic. -Carly Barry
When I first started working among quality improvement professionals, I was caught off-guard by the varying terminology for "quality improvement." Some companies call their quality programs “process excellence initiatives” or “continuous quality improvement,” while others refer to their programs as “Lean” or “Lean Six Sigma." Others subtract ‘lean’ from their program titles altogether, and refer to their efforts simply as “Six Sigma.”
Are there really any differences, or is all of this terminology just jargon for ‘process improvement?’ The short answer to that question is that it all means process improvement, but there are some key differences to be aware of.
Lean vs. Six Sigma
First off, understand that there is a strong connection between Lean and Six Sigma. Both methodologies seek to make processes and the business as a whole more efficient by removing defects or waste through focused efforts that likely involve a project-based approach.
However, Lean refers to activities that are meant to be quick and efficient (see this post about performing kaizen or “blitz” improvements), while Six Sigma projects are meant to be thorough and permanent. Six Sigma operates off of the data-driven DMAIC approach, where projects are broken down into the five phases of Define, Measure, Analyze, Improve, and Control. In Six Sigma projects, all improvement efforts must be proven statistically significant, and this is where statistical software like Minitab can come in handy.
Lean projects are more loosely based and not as phase-driven, although most Lean activities also can be done within the framework of a Six Sigma DMAIC project. Some Lean tools, such as SIPOC and FMEA, have become strongly tied to specific DMAIC phases. For example, you’d likely perform a SIPOC or FMEA in the project selection or project scoping portion of the ‘Define’ phase.
The opposite is not true though – not all Six Sigma tools can fit into Lean. A three-dimensional response surface DOE is too complex and requires much more of a time investment than a typical Lean tool would require. But just because Lean tools aren’t as complex as some Six Sigma tools, it doesn’t mean they aren’t powerful and effective. In fact, unlike traditional Six Sigma methods, many Lean tools are easily and directly used by individuals of all skill levels with minimal training.
A Battle of Methodologies?
In talking with various quality professionals at different organizations, I’ve noticed that there can be battles internally where proponents of Lean and proponents of Six Sigma form individual silos. Both sides do not see the full value of each other’s methods and toolkits. Is this true at your organization?
The key is to strike a happy medium and use both methodologies where it makes sense. Remember that the right tools should be used for the problem at hand, even if those tools fall within the Lean methodology, and you are technically supposed to be working on a 'Six Sigma' project.
Regardless of what you call your quality improvement endeavor, keep an open mind and rely on data analysis to drive improvements. Personally, I think Lean and Six Sigma are like peanut butter and jelly, or even Laverne and Shirley. You certainly can’t have one without the other!
What is the name of your company’s quality improvement program? Does the name reflect the tools you use?