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. The approach was based on the methods taught by W. Edwards Deming
Dr. William Edwards Deming (October 14, 1900 – December 20, 1993) was an engineer, statistician, professor, author, lecturer, and management consultant He helped develop the sampling techniques still used by the U.S. Department of the Census and the Bureau of Labor Statistics. Deming championed the work of Walter Shewhart, including statistical process control, operational definitions, and what Deming called the "Shewhart Cycle" which had evolved into Plan-Do-Study-Act (PDSA). This was in response to the growing popularity of Plan-Do-Check-Act (PDCA), which Deming viewed as tampering with the meaning of Shewhart's original work.
Deming made a significant contribution to Japan's reputation for innovative, high-quality products after World War II. He is regarded as having had more impact on Japanese manufacturing and business than any other individual not of Japanese heritage. Despite being honored in Japan in 1951 with the establishment of the Deming Prize.
Japanese Union of Scientists and Engineers (JUSE)
The W. Edwards Deming Institute
Out of the Crisis
The New Economics
On June 24, 1980, Americans widely viewed a NBC documentary called “If Japan Can… Why Can’t We.” The program, part of NBC’s White Paper series, prominently featured Dr. W. Edwards Deming. This compelling documentary introduced Dr. Deming to Americans. For the first time, they learned of the then 80-year old American who was widely credited with the Japanese industrial resurgence after WWII.
Dr. Deming discusses his 14 Points for Management in the video below. Read the full excerpt
Dr. Deming used the Red Bead Experiment to clearly and dramatically illustrate several points about poor management practices. This includes the fallacy of rating people and ranking them in order of performance for next year, based on previous performance. It uses statistical theory to show that even though a “willing worker” wants to do a good job, their success is directly tied to and limited by the nature of the system they are working within. Real and sustainable improvement on the part of the willing worker is achieved only when management is able to improve the system.
Walter A. Shewhart (March 18, 1891 – March 11, 1967) was known as the father of statistical quality control (SQC or SPC) and is also the founder of the "Shewhart cycle" or Plan Do Check Act (PDCA).
He developed his skills while working at Bell Telephone to improve the reliability of their transmission systems, and later improve the voice clarity of the carbon transmitters in the company's telephone handsets.
Shewhart's work focused on reducing variation in a manufacturing process. He framed the problem in terms of assignable-cause (special cause) and chance-cause (common cause) variation, and introduced the control chart as a tool for distinguishing between the two.
W. Edwards Deming
Indian Statistical Institute
Western Electric Company
Economic Control of Quality Of Manufactured Product
Statistical Method from the Viewpoint of Quality Control
Sir Ronald Aylmer Fisher (17 February 1890 – 29 July 1962) was a British statistician and geneticist, who is considered "the single most important figure in 20th century statistics."
He is responsible for, popularized, or is credited with the following statistical techniques:
Analysis of Variance (ANOVA) - technique developed from decades of crop experiment to quantify the statistical significance of factors on the overall variation in the data.
P-value - Fisher popularized the concept, and proposed the level p=0.05, or a 1 in 20 chance of being exceeded by chance, as a limit for statistical significance.
Design of experiments (DOE) - principles of the design of experiments
F-distribution - Originally called Fisher's z-distribution, it was a new statistical method which was later called the Fisher–Snedecor (F) distribution.
Fisher's exact test - statistical significance test used in the analysis of a 2x2 contingency tables
Student's t-distribution - popularized the distribution for small samples, and called it "Student's distribution" and represented the test value with the letter t.
Fisher's permutation test
Fisher's equation - Also known as Kolmogorov-Petrovsky–Piskunov equation for partial differentials
The R. A. Fisher Lectureship is a very high recognition annual lecture prize established in 1963 in North America. It is given in recognition of achievement and scholarship in statistical science for those who have a highly significant impact of statistical methods on scientific investigations. It provides the lecturer with a plaque and a cash award of $1000 USD.
In 1998, a minor planet, 21451 Fisher, was named after him.
W. Edwards Deming
Statistical Methods for Research Workers
The Genetical Theory of Natural Selection
">Ronald Fisher among many others. Hundreds of companies around the world have adopted Six Sigma as a way of doing business.
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.