Emma Reinisch
"Six Sigma is a disciplined, statistical-based, data-driven approach and continuous improvement methodology for eliminating defects in a product, process or service. It was developed by Motorola and Bill Smith in the early 1980’s based on quality management fundamentals, then became a popular management approach at General Electric (GE) with Jack Welch in the early 1990’s... Hundreds of companies around the world have adopted Six Sigma as a way of doing business.
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Sigma represents the population standard deviation, which is a measure of the variation in a data set collected about the process. If a defect is defined by specification limits separating good from bad outcomes of a process, then a six sigma process has a process mean (average) that is six standard deviations from the nearest specification limit. This provides enough buffer between the process natural variation and the specification limits... Six Sigma can also be thought of as a measure of process performance, with Six Sigma being the goal, based on the defects per million."
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