Six Sigma, 3.4 defects per million or less.

While the particulars of the methodology were originally formulated by Bill Smith at Motorola in 1986,[2] Six Sigma was heavily inspired by six preceding decades of quality improvement methodologies such as quality control, TQM, and Zero Defects. Like its predecessors, Six Sigma asserts the following:

Continuous efforts to reduce variation in process outputs is key to business success.

Manufacturing and business processes can be measured, analyzed, improved and controlled. Succeeding at achieving sustained quality improvement requires commitment from the entire organization, particularly from top-level management.

The term "Six Sigma" refers to the ability of highly capable processes to produce output within specification. In particular, processes that operate with six sigma quality produce at defect levels below 3.4 defects per (one) million opportunities (DPMO).[3] Six Sigma's implicit goal is to improve all processes to that level of quality or better.

Six Sigma is a registered service mark and trademark of Motorola, Inc.[4] Motorola has reported over US$17 billion in savings[5] from Six Sigma as of 2006.