Six Sigma

Reviewed by Anjaneyulu | Updated on Aug 27, 2020


American engineer, Bill Smith, invented Six Sigma while working at Motorola in 1986. Jack Welch made it central to his business plan for General Electric (GE) in 1995. Six Sigma is a collection of process management methods and tools. A Six Sigma process is statistically assumed to be free of defects, at 99.99966% of all possibilities, to manufacture any function of a component.


Six Sigma approach seeks to increase the efficiency and production of a process by recognizing and reducing the causes of defects and decreasing the volatility of impacts in manufacturing and business processes. It uses a range of quality control methods, primarily analytical and statistical methods. Further, it establishes a specific network of people who are experts in these methods in the company.

Six Sigma project undertaken within a company follows a prescribed sequence of steps. It has clear value goals, such as reducing product cycle times, reducing emissions, reducing costs, increasing customer satisfaction, and increasing profits.

Six Sigma projects have two methodologies inspired by Deming's Plan–Do–Study–Act Cycle and they are comprised of five phases each, which bear the acronyms DMAIC and DMADV.


Six Sigma sees implementation mainly in large organizations. Six Sigma contains a large number of tools and techniques that work well in small-to-medium-sized organizations. According to industry analysts, businesses with less than 500 employees are less suited to adopting Six Sigma.


As part of their implementation of Six Sigma, General Electric and Motorola developed qualification systems, testing the command of the Six Sigma principles by individuals at the appropriate ability level (Green Belt, Black Belt etc.). In the 1990s, several companies started providing Six Sigma certifications to their staff using this strategy.

In 2008, Motorola University later co-developed a set of comparable Lean Quality criteria with Vative and the Lean Six Sigma Society of Professionals. The requirements for the qualification of the Green Belt and the Black Belt vary. Some organizations require participation in a course and a Six Sigma project.