Six Sigma – in 3 minutes


The basics
Is a structured, disciplined and rigorous approach and methodology for process improvement through identifying and eliminating defects. It is a business management strategy, originally developed by Motorola, USA in 1986

The use of Six Sigma as a measurement standard is based on the concept of the normal curve, dating from the 1920s, when Shewhart demonstrated that three sigma (standard deviations) from the mean is a point where a process requires correction. In the mid-1980s Motorola engineers started to measure defects in millions per opportunities to provide adequate detail in measuring quality levels. The term ‘Six Sigma’ was coined in that period by one of the involved engineers, Smith.
Six Sigma refers to the statistical notion of having a 99.99 per cent confidence of achieving specified results. A greater sigma implies a lower expected Defects per Million Opportunities (DMO) for defect or error. The statistical representation of Six Sigma describes quantitatively how a process is performing. To achieve Six Sigma a process must not produce more than 3.4 defects per million opportunities, where a defect is defined as anything outside customer specifications.

Six Sigma can be perceived at three levels:

1.    Metric: 3,4 Defects Per Million Opportunities (DPMO)

2.    Methodology:

–       DMAIC (Define-Measure-Analyze-Improve) is a structured problem solving roadmap and tools.

–       DMADV (Define-Measure-Analyze-Design-Verify) is a data driven quality strategy for designing product and processes

–       DFSS (Design For Six Sigma) is an approach for the deployment of Six Sigma

3.    Philosophy: reduce variation in the business and take customer-focused, data-driven decisions by implementing an measurement-based strategy that focuses on process improvement and variation reduction through the application of Six Sigma improvements projects.

Six Sigma uses a set of quality management techniques, including statistical information, and creates a unique infrastructure of people within the organization (‘Black Belts’, ‘Green Belts’, etc.) who are experts in Six Sigma. Each Six Sigma project carried out within an organization follows a defined sequence of steps and has quantified project targets (such as cost reduction and/or profit increase).

Target audience
Six Sigma can be used by anybody who is involved in process improvement such as business analysts, engineers, project managers and advisors.

Scope and constraintsThe scope of Six Sigma is any process in any type of organization – from manufacturing to transactions and from product to service where an approach and methodology is needed for eliminating defects.Six Sigma is complementary to ‘lean’ approaches, which focus on the elimination of wasteful process activities. Some practitioners have combined Six Sigma ideas with lean thinking to create a methodology called Lean Six Sigma.
·         A secure, rigorous and structured method;
·         A fact based approach (statistical instead of based on intuition);
·         Trained resources with appropriate skills
·         Fast implementation.
·         Using Six Sigma for processes with a low volume of output. This can produce unreliable results.
·         Not enough statistical knowledge available in order to be able to use sophisticated statistical methods. Extensive training is needed for correct use of the approach.
Relevant links (web links)
International Society of Six Sigma Professionals :

Knowledge database website:

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