Six Sigama

Six Sigama


Six Sigma (6σ) is a set of techniques and tools for process improvement. It was introduced by engineers Bill Smith & Mikel J Harry while working at Motorola in 1986. Jack Welch made it central to his business strategy at General Electric in 1995.

It seeks to improve the quality of the output of a process by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes. It uses a set of quality management methods, mainly empirical, statistical methods, and creates a special infrastructure of people within the organization who are experts in these methods. Each Six Sigma project carried out within an organization follows a defined sequence of steps and has specific value targets, for example: reduce process cycle time, reduce pollution, reduce costs, increase customer satisfaction, and increase profits.

The term Six Sigma (capitalized because it was written that way when registered as a Motorola trademark on December 28, 1993) originated from terminology associated with statistical modeling of manufacturing processes. The maturity of a manufacturing process can be described by a sigma rating indicating its yield or the percentage of defect-free products it creates. A six sigma process is one in which 99.99966% of all opportunities to produce some feature of a part are statistically expected to be free of defects (3.4 defective features per million opportunities). Motorola set a goal of "six sigma" for all of its manufacturing operations, and this goal became a by-word for the management and engineering practices used to achieve it.

Six Sigma doctrine asserts:

  • Continuous efforts to achieve stable and predictable process results (e.g. by reducing process variation) are of vital importance to business success
  • Manufacturing and business processes have characteristics that can be defined, measured, analyzed, improved, and controlled
  • Achieving sustained quality improvement requires commitment from the entire organization, particularly from top-level management

Features that set Six Sigma apart from previous quality-improvement initiatives include:

    A clear focus on achieving measurable and quantifiable financial returns from any Six Sigma project An increased emphasis on strong and passionate management leadership and support A clear commitment to making decisions on the basis of verifiable data and statistical methods, rather than assumptions and guesswork