In response to a message from a colleague asking about the relationship between Lean, Six Sigma and Quality, I wrote the following:
Both Lean and Six Sigma (and Lean Six Sigma, the combination of the two) are ways of improving operational excellence. Lean does this by improving flow through value streams, primarily focusing on the elimination of various forms of muda (waste.) Six Sigma does this by identifying what customers and other stakeholders want and delivering it with minimal waste, variation and errors.
The Lean and Six Sigma DMAIC disciplines focus on the processes for creating and delivering products and services that meet or exceed customer expectations. The Design for Six Sigma discipline focuses on the design of products or services that meet or exceed customer expectations. Quality is a discipline which focuses on identifying customer requirements and expectations, translating them into internal requirements, and assuring that the requirements are consistently met. Of course, these Quality activities provide input into both Lean and Six Sigma. It is the “Y” being solved for when waste is identified (Lean) or when searching for the root causes of waste, variation and errors (Six Sigma.)
Thus, Lean, Quality, and Six Sigma are all different aspects of excellence.
I welcome your comments on how you consider the three areas to be related. Or do you consider them to be unrelated ideas?