Six Sigma is a highly disciplined and structured framework for delivering high quality products or services. Six Sigma is also a set of tools for statistical analysis, displaying process data, working in teams, project management, and managing change.
The Six Sigma improvement framework specifies five steps that occur in a precise sequence, used for understanding and improving any process, known as DMAIC:
- Define
- Measure
- Analyze
- Improve
- Control
Approach improvement to projects with Lean-Six Sigma methodology
One significant change from how improvement projects were approached in general improvement models was to more clearly define specific targets to improve. By more explicitly defining the problem in a "problem statement" at the start of the project, the results of improvement projects were greatly enhanced. This change in approach may seem obvious and simple, yet what had been revealed by previous improvement methodologies in the past has been less successful than planned, and in part simply because the scope of the project was poorly defined in the beginning for both participants and those outside the improvement team. As a result, the "classic" improvement model of the Plan-Do-Check-Act (PDCA) was expanded into a five-step improvement methodology which included a DEFINE phase. The define phase has served to help projects narrow and more precisely define their scope and targets, and this has focused energies on what was critical for success, as well as doing a much better job of communicating project goals and outcomes to key stakeholders throughout the organization. Now, all Six Sigma process improvement projects follow the expanded five-step methodology of DMAIC. There are many variations in the application of Lean and Six Sigma tools, but the "toolkit" itself has been well documented and incorporated into a working body of knowledge accessible to everyone at every level of an organization.
Lean principles and Six Sigma methods work together within the DMAIC model. Six Sigma tools focus primarily on process outputs, while Lean production methods focus on process throughput. Lean and Six Sigma help organizations tackle short- and long-term improvement goals.