Six Sigma is a set of practices originally developed by Motorola to
systematically improve processes by eliminating defects. A defect is defined as
nonconformity of a product or service to its specifications.
While the particulars of the methodology were originally formulated by Bill
Smith at Motorola in 1986, 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
Manufacturing and business processes can be measured, analyzed, improved
Succeeding at achieving sustained quality improvement requires
commitment from the entire organization, particularly from top-level
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). 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.
Motorola has reported over US$17 billion in savings
from Six Sigma as of 2006.
In addition to Motorola, companies that adopted Six Sigma methodologies early
on and continue to practice it today include Honeywell International (previously
known as Allied Signal) and General Electric (introduced by Jack Welch).
Recently some practitioners have used the TRIZ methodology for problem
solving and product design as part of a Six sigma approach.