wht is six sigma ??

Six Sigma is a data driven improvement methodology aimed to improve mean and reduce variation in the desired CTQ (critical-to-quality) characteristics. CTQ would be any dimension of the performance be it schedule adherence, on time delivery, response time, resource utilisation etc.,

Six Sigma was originally developed as a set of practices designed to improve manufacturing processes and eliminate defects, but its application was subsequently extended to other types of business processes as well.^[2] In Six Sigma, a defect is defined as anything that could lead to customer dissatisfaction.^[1]

The particulars of the methodology were first formulated by Bill Smith at Motorola in 1986.^[3] Six Sigma was heavily inspired by six preceding decades of quality improvement methodologies such as quality control, TQM, and Zero Defects,^[4][5] based on the work of pioneers such as Shewhart, Deming, Juran, Ishikawa, Taguchi and others.

Like its predecessors, Six Sigma asserts that –

• Continuous efforts to achieve stable and predictable process results (i.e. reduce process variation) are of vital importance to business success.
• Manufacturing and business processes have characteristics that can be 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.^[1]
• An increased emphasis on strong and passionate management leadership and support.^[1]
• A special infrastructure of "Champions," "Master Black Belts," "Black Belts," etc. to lead and implement the Six Sigma approach.^[1]
• A clear commitment to making decisions on the basis of verifiable data, rather than assumptions and guesswork.^[1]

The term "Six Sigma" is derived from a field of statistics known as process capability studies. 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).^[6][7] 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.^[8] Motorola has reported over US$17 billion in savings^[9] from Six Sigma as of 2006.

Other early adopters of Six Sigma who achieved well-publicized success include Honeywell (previously known as AlliedSignal) and General Electric, where the method was introduced by Jack Welch.^[10] By the late 1990s, about two-thirds of the Fortune 500 organizations had begun Six Sigma initiatives with the aim of reducing costs and improving quality.^[11]

In recent years, Six Sigma has sometimes been combined with lean manufacturing to yield a methodology named Lean Six Sigma.