Six Sigma as a Business Improvement Methodology

Six Sigma is a set of practices originally developed by Motorola to systematically improve processes by eliminating defects. The term "Six Sigma" refers to the ability of highly capable processes to produce output within specification. As a quality control metric, "Six Sigma" equates to 3.4 defects per one million opportunities (DPMO). Six Sigma's implicit goal is to improve all processes to that level of quality or better.
Six Sigma methodology focuses on the implementation of a measurement-based strategy to achieve the process improvement and variation reduction. This approach is based on two basic Six Sigma models: DMAIC process (Define, Measure, Analyze, Improve, and Control) and DMADV (Define, Measure, Analyze, Design, and Verify). The Six Sigma DMAIC is an improvement system for existing processes falling below specification and looking for incremental improvement. The Six Sigma DMADV process is an improvement system used to develop new processes or products at Six Sigma quality levels. It can also be employed if a current process requires more than just incremental improvement.