Many people ask “Which should I implement first, Lean or Six Sigma?” The question is pretty easy to answer.

1st – Stabilize the Process: Lean Transformation procedures are much easy to teach and can be implemented much faster than six sigma procedures unless you are using the services of an outside consultant or agency. Lean procedures are designed to identify and eliminate waste to stabilize operations and smooth out the flow throughout the value stream. Providing an organization can establish a continuous improvement infrastructure to support their lean improvement efforts, they will soon start to see positive results. 

2^nd – Reduce Process Variation: Six Sigma on the other hand, is a little more complex because it requires practitioners to undertake specialist training courses. The training and competency levels are defined by the colored belts used in martial arts i.e. white, yellow, green and black belts. The training can take anywhere from several weeks to several months to complete before the practitioner is capable of conducting their own project work. Lower belts usually work under the oversight of a higher level belt e.g. black belts will provide oversight and support to green belts. Six Sigma requires an organization to establish a robust infrastructure that can support the training needs and project oversight for its practitioners and continuous improvement system. 

Combination of Lean and Six Sigma: During the 21st century, many organizations have adopted a methodology called “Lean Six Sigma.” This is where Lean methods have been integrated and combined with Six Sigma methods. There are pros and cons for all improvement methodologies, it all depends on why and where they are being used. 

The image below demonstrates the sigma range when implementing either Lean and Six Sigma procedures. Lean was originally designed to improve and control processes up to 3 sigma (or 99.73% yield). The image clearly demonstrates that the key focus of a Lean methodology is identifying and eliminating waste to improve Process Velocity. On the other hand, Six Sigma is focused on identifying and eliminating the root cause(s) of Process Variation to improve and control processes up to 6 sigma (3.4 defects per million opportunities or 99.99966% yield).