Double LEAN Six Sigma – A Structure for Applying Lean Six Sigma

Mark Gershon

You’ve heard of Lean. You’ve heard of Lean Six Sigma. But have you heard of the "Double Lean" approach? Here Mark Gherson describes what it is and argues that it is more prescriptive and easier to use than DMAIC.

Editor's note: This is an extract of a report published in the Journal of Applied Business and Economic. For the full report please click here.

There are a variety of ways to introduce Six Sigma into a company, involving different levels of structure, time frames, costs and management commitments. But all agree on the basic steps of the improvement process, the five stages of the DMAIC process. DMAIC is synonymous with Six Sigma when talking about the process to follow, the steps.

In recent years, however, new developments in Six Sigma have led to the amalgamation of the "lean" tools to bring about certain changes in the methodology and expedite the results. In this context "Lean Six Sigma" (LSS) has now become the industry flavor and many applications are being cited to show its popularity.

To date, however, the proponents of Lean Six Sigma have failed to develop a process to prescribe how to apply Lean Six Sigma. Most articles and textbooks on LSS read like Six Sigma texts with the word "lean" added many times, especially in the title, and with some of the lean tools added to the tool kit. But the process followed is DMAIC with no changes. If that is all Lean Six Sigma is, then it is still just Six Sigma.

Lean Six Sigma (LSS) is understood as integrating Six Sigma and the Lean tools to reap the benefits of both. While the term "Lean Six Sigma" is quite commonly used, the definition varies across different sources and doesn’t mean the same thing. Some common perceptions about Lean Six Sigma (LSS) are:

  • It is a condensed and less costly version of Six Sigma
  • It is Six Sigma on a fast track (less completion time)
  • It is Six Sigma combined with lean tools for better results

Because of these differences in their practice and adaptation, Lean Six Sigma does not have a universally common meaning or implementation procedure. But one thing that is quickly recognized is that Lean Six Sigma takes much less time and other resources so that the results are visible in a shorter span of time. It is this perceived image that has made it popular and attractive to industries. In fact, that is the reason for the order of the perceptions just provided. Most companies are adopting it for the first two reasons, not necessarily the inclusion of the Lean tools.

Why Lean Six Sigma?

In practice, it can be seen that the reasons for adopting Lean Six Sigma stem from four fundamental barriers to adopting Six Sigma. The first barrier is just the size and number of roles in the Six Sigma structure. The second barrier is the amount of training involved.

The third barrier is the time it will take to yield results. The fourth barrier is the cultural change required to make it work.

Most companies adopting this Lean version of Six Sigma are doing it for cost reasons.

They know that Six Sigma is popular and effective, but are not willing to invest in setting up the program and all of the training that is required. The Lean version is sold as having little or no infrastructure. All you have to do is to set up a few improvement teams, task them with a process to look at, and get them going. So, Lean here actually means "cheap" as opposed to the meaning we have been developing.

This leads to the another reason beyond lower cost, faster results. In the Lean version, we go straight for the projects and the results, and within a month or two can show savings or improvement to a process. In the traditional Six Sigma approach, it takes months to get things set up, and then a typical project team can take months more to get results. So here the word Lean is used to mean "quick" again different than the true meaning.

How to Conduct the Improvement Project - The Double LEAN Method

A Six Sigma project follows the DMAIC process steps. But there are problems with this approach. The five phases take too long to complete, delaying results. More importantly, it misses key steps and is unclear in where to finish one phase and begin the next.

For an example of how the delineation of the phases is not clear, look at the line between Define and Measure. Define should state the goal for the project, but too often this cannot be done until results are in from the Measure phase. So Define is not complete until much of Measure is complete. The lines are blurred.

In response to this, a new approach is proposed, using the "LL-EE-AA-NN" acronym for the Double LEAN Approach. Each of the letters represents a particular action to be taken up by the group or the team responsible for quality improvement. Further every two letters of the acronym constitute a phase and thus four phases are involved in the proposed methodology.

By having four phases instead of five, the time to completion is already reduced. By having clear lines between the phases, or phase gates, the conduct of the projects is made more clear and easier.

The tools used are the same common tools used in Lean and Six Sigma. The phases are:

PHASE 1 – Look and Locate

PHASE 2 – Explore and Establish

PHASE 3 – Analyze and Apply

PHASE 4 – New and Navigate

The Double LEAN method is more prescriptive and easier to use than the DMAIC. In addition, the establishment of phase gates is a major improvement over the DMAIC. It is also shown that it can be implemented with no prior training.