Six Sigma is a set of techniques and tools for process improvement. It was developed by Motorola in 1986. Jack Welch made it central to his business strategy at General Electric in 1995. Today, it is used in many sectors.
The term “Six Sigma” comes from statistics and is used in statistical quality control, which evaluates process capability. Originally, it referred to the ability of manufacturing processes to produce a very high proportion of output within specification. Processes that operate with “six sigma quality” over the short term are assumed to produce long-term defect levels below 3.4 Defects Per Million Opportunities (DPMO). Six Sigma’s implicit goal is to improve all processes, but not to the 3.4 DPMO level necessarily.
Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects (errors) and minimizing variability in manufacturing and business processes. It uses a set of quality management methods, including statistical methods, and creates a special infrastructure of people within the organization.
Organizations need to determine an appropriate sigma level for each of their most important processes and strive to achieve these. As a result of this goal, it is incumbent on management of the organization to prioritize areas of improvement.