Gen'ichi Taguchi (田口 玄一) (born January 1, 1924 in Tokamachi, Japan) is an engineer and statistician. From the 1950s onwards, Taguchi developed a methodology for applying statistics to improve the quality of manufactured goods. Taguchi methods have been controversial among many conventional Western statisticians unfamiliar with the Taguchi methodology. January 1 is the first day of the calendar year in both the Julian and Gregorian calendars. ... 1924 (MCMXXIV) was a leap year starting on Tuesday (link will take you to calendar). ... Tōkamachi (十日町市; -shi) is a city located in Niigata, Japan. ... Look up engineer in Wiktionary, the free dictionary. ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ... The 1950s was the decade spanning the years 1950 to 1959. ... A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ... Taguchi methods are statistical methods developed by Genichi Taguchi to improve the quality of manufactured goods. ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ...

Life

Taguchi was raised in the textile town of Tokamachi where he initially studied textile engineering with the intention of entering the family kimono business. However, with the escallation of World War II, in 1942, he was drafted into the Astronomical Department of the Navigation Institute of the Imperial Japanese Navy. Tōkamachi (十日町市; -shi) is a city located in Niigata, Japan. ... Engineering is the application of scientific and mathematical principles to develop economical solutions to technical problems, creating products, facilities, and structures that are useful to people. ... Kimono (Japanese: 着物, literally something worn, i. ... Combatants Major Allied powers: United Kingdom Soviet Union United States Republic of China and others Major Axis powers: Nazi Germany Italy Japan and others Commanders Winston Churchill Joseph Stalin Franklin Roosevelt Harry Truman Chiang Kai-Shek Adolf Hitler Benito Mussolini Hideki Tojo Casualties Military dead: 17,000,000 Civilian dead... 1942 (MCMXLII) was a common year starting on Thursday (the link is to a full 1942 calendar). ... The Imperial Japanese Navy (IJN) (: 大日本帝國海軍 Shinjitai: 大日本帝国海軍 or 日本海軍 Nippon Kaigun) or sometimes referred to as the Combined Fleet was the Navy of Empire of Japan (Dai Nippon Teikoku) from 1869 until 1947, when it was dissolved following Japans constitutional renunciation of the use of force as a means of settling...

After the war, in 1948, he joined the Ministry of Public Health and Welfare where he came under the influence of eminent statistician Matosaburo Masuyama who kindled his interest in design of experiments. He also worked at the Institute of Statistical Mathematics, during this time, and supported experimental work on the production of penicillin at Morinaga Pharmaceuticals, a Morinaga Seika company. 1948 (MCMXLVIII) was a leap year starting on Thursday (the link is to a full 1948 calendar). ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ... Motosaburo Masuyama (1912 - 3 July 2005) was a Japanese statistician who championed the ideas of R.A. Fisher and went on to influence the fields of quality control and biometrics. ... The first statistician to consider a methodology for the design of experiments was Sir Ronald A. Fisher. ... The Institute of Statistical Mathematics is Japans national research institute for statistical science, located in the Azabu district of Tokyo. ... Penicillin nucleus Penicillin (sometimes abbreviated PCN) refers to a group of β-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ...

In 1950, he joined the Electrical Communications Laboratory (ECL) of the Nippon Telegraph and Telephone Corporation just as statistical quality control was beginning to become popular in Japan under the influence of W. Edwards Deming and the Japanese Union of Scientists and Engineers. ECL was engaged in a rivalry with Bell Labs to develop cross bar and telephone switching systems and Taguchi spent his twelve years there in developing methods for enhancing quality and reliability. Even at this point, he was beginning to consult widely in Japanese industry, with Toyota being an early adopter of his ideas. 1950 (MCML) was a common year starting on Sunday (link will take you to calendar). ... Nippon Telegraph and Telephone (日本電信電話 Nippon Denshin Denwa) is a telephone company that dominates the telecommunication market in Japan. ... William Edwards Deming (October 14, 1900 - December 20, 1993) was an American statistician, college professor, author, and lecturer widely credited with improving production in the United States during World War II. However, Deming is perhaps best known for his work in Japan; where from 1950 onward he taught top management... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... Toyota redirects here. ...

During the 1950s, he collaborated widely and in 1954-1955 was visiting professor at the Indian Statistical Institute where he worked with R. A. Fisher and Walter A. Shewhart. The 1950s was the decade spanning the years 1950 to 1959. ... 1954 (MCMLIV) was a common year starting on Friday of the Gregorian calendar. ... 1955 (MCMLV) was a common year starting on Saturday of the Gregorian calendar. ... Indian Statistical Institute (ISI), is a unique institution devoted to the research, teaching and application of statistics, natural sciences and social sciences. ... Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a English statistician, evolutionary biologist, and geneticist. ... Walter Andrew Shewhart (March 18, 1891 - March 11, 1967) was a physicist, engineer and statistician, sometimes known as the father of statistical quality control. ...

On completing his doctorate from Kyushu University in 1962, he left ECL, though he maintained a consulting relationship. In the same year he visited Princeton University under the sponsorship of John Tukey who arranged a spell at Bell Labs, his old ECL rivals. In 1964 he became professor of engineering at Aoyama Gakuin University, Tokyo. In 1966 he began a collaboration with Yuin Wu who later emigrated to the USA and, in 1980, invited Taguchi to lecture. During his visit there, Taguchi himself financed a return to Bell Labs where his initial teaching had made little enduring impact. This second visit began a collaboration with Madhav Phadke and a growing enthusiasm with his methodology in Bell Labs and elsewhere, including Ford Motor Company, Xerox and ITT. Kyushu University (九州大学 KyÅ«shÅ« Daigaku, abbreviated to 九大 KyÅ«dai) in Fukuoka City is one of Japans most prestigious national universities and the largest public university on the island of Kyushu. ... 1962 (MCMLXII) was a common year starting on Monday (the link is to a full 1962 calendar). ... Princeton University is a coeducational private university located in Princeton, New Jersey in the United States of America. ... John Wilder Tukey (June 16, 1915 - July 26, 2000) was a statistician. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... 1964 (MCMLXIV) was a leap year starting on Wednesday (the link is to a full 1964 calendar). ... Engineering is the application of scientific and mathematical principles to develop economical solutions to technical problems, creating products, facilities, and structures that are useful to people. ... Aoyama Gakuin is an educational institute in Tokyo, Japan, which comprises Aoyama Gakuin University, Aoyama Gakuin Women’s Junior College, Aoyama Gakuin Senior High School, Aoyama Gakuin Junior High School, Aoyama Gakuin Elementary School, and Aoyama Gakuin Kindergarten. ... Tokyo , literally Eastern capital)   is the capital and one of the forty-seven prefectures of Japan. ... 1966 (MCMLXVI) was a common year starting on Saturday (the link is to a full 1966 calendar). ... 1980 (MCMLXXX) was a leap year starting on Tuesday. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... now. ... Xerox Corporation (NYSE: XRX) (pronounced ) is an American document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Since 1982, Genichi Taguchi has been an advisor to the Japanese Standards Institute and executive director of the American Supplier Institute, an international consulting organisation. 1982 (MCMLXXXII) was a common year starting on Friday of the Gregorian calendar. ...

Contributions

Loss functions

Taguchi's reaction to the classical design of experiments methodology of R. A. Fisher was that it was perfectly adapted in seeking to improve the mean outcome of a process. As Fisher's work had been largely motivated by programmes to increase agricultural production, this was hardly surprising. However, Taguchi realised that in much industrial production, there is a need to produce an outcome on target, for example, to machine a hole to a specified diameter or to manufacture a cell to produce a given voltage. He also realised, as had Walter A. Shewhart and others before him, that excessive variation lay at the root of poor manufactured quality and that reacting to individual items inside and outside specification was counter-productive. The first statistician to consider a methodology for the design of experiments was Sir Ronald A. Fisher. ... Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a English statistician, evolutionary biologist, and geneticist. ... In statistics, mean has two related meanings: the average in ordinary English, which is also called the arithmetic mean (and is distinguished from the geometric mean or harmonic mean). ... Process (lat. ... Wind turbines A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. ... Diameter is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... An electrochemical cell is a setup used for creating an electromotive force(voltage) in a conductor separating two reactions. ... now. ... Walter Andrew Shewhart (March 18, 1891 - March 11, 1967) was a physicist, engineer and statistician, sometimes known as the father of statistical quality control. ...

He, therefore, argued that quality engineering should start with an understanding of the cost of poor quality in various situations. In much conventional industrial engineering the cost of poor quality is simply represented by the number of items outside specification multiplied by the cost of rework or scrap. However, Taguchi insisted that manufacturers broaden their horizons to consider cost to society. Though the short-term costs may simply be those of non-conformance, any item manufactured away from nominal would result in some loss to the customer or the wider community through early wear-out; difficulties in interfacing with other parts, themselves probably wide of nominal; or the need to build-in safety margins. These losses are externalities and are usually ignored by manufacturers. In the wider economy the Coase Theorem predicts that they prevent markets from operating efficiently. Taguchi argued that such losses would inevitably find their way back to the originating corporation (in an effect similar to the tragedy of the commons) and that by working to minimise them, manufacturers would enhance brand reputation, win markets and generate profits. Industrial Engineering is one of the branches in engineering that concerns the development, improvement, implementation and evaluation of integrated systems of people, knowledge, equipment, energy, material and process. ... An externality occurs in economics when a decision (for example, to pollute the atmosphere) causes costs or benefits to individuals or groups other than the person making the decision. ... In law and economics, the Coase theorem, attributed to Ronald Coase, relates to the economic efficiency of a governments allocation of property rights. ... It has been suggested that Tyranny of the Commons be merged into this article or section. ...

Such losses are, of course, very small when an item is near to nominal. Donald J. Wheeler characterised the region within specification limits as where we deny that losses exist. As we diverge from nominal, losses grow until the point where losses are too great to deny and the specification limit is drawn. All these losses are, as W. Edwards Deming would describe them, ...unknown and unknowable but Taguchi wanted to find a useful way of representing them within statistics. Taguchi specified three situations: William Edwards Deming (October 14, 1900 - December 20, 1993) was an American statistician, college professor, author, and lecturer widely credited with improving production in the United States during World War II. However, Deming is perhaps best known for his work in Japan; where from 1950 onward he taught top management... A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ...

1. Larger the better (for example, agricultural yield);
2. Smaller the better (for example, carbon dioxide emissions); and
3. On-target, minimum-variation (for example, a mating part in an assembly).

The first two cases are represented by simple monotonic loss-functions. In the third case, Taguchi adopted a squared-error loss function on the grounds: Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... In mathematics, functions between ordered sets are monotonic (or monotone, or even isotone) if they preserve the given order. ...

• It is the first symmetric term in the Taylor series expansion of any reasonable, real-life loss function, and so is a "first-order" approximation;
• Total loss is measured by the variance. As variance is additive it is an attractive model of cost; and
• There was an established body of statistical theory around the use of the least-squares principle.

The squared-error loss function had been used by John von Neumann and Oskar Morgenstern in the 1930s. As the degree of the Taylor series rises, it approaches the correct function. ... In probability theory and statistics, the variance of a random variable (or equivalently, of a probability distribution) is a measure of its statistical dispersion, indicating how its possible values are spread around the expected value. ... In probability theory and statistics, the variance of a random variable (or equivalently, of a probability distribution) is a measure of its statistical dispersion, indicating how its possible values are spread around the expected value. ... The theory of statistics includes a number of topics: Statistical models of the sources of data and typical problem formulation: Sampling from a finite population Measuring observational error and refining procedures Studying statistical relations Planning statistical research to measure and control observational error: Design of experiments to determine treatment effects... John von Neumann in the 1940s. ... Oskar Morgenstern (January 24, 1902 - July 26, 1977) was an German- American economist who, working with John von Neumann, helped found the mathematical field of game theory. ... This article or section does not cite its references or sources. ...

Though much of this thinking is endorsed by statisticians and economists in general, Taguchi extended the argument to insist that industrial experiments seek to maximise an appropriate signal to noise ratio representing the magnitude of the mean of a process, compared to its variation. Most statisticians believe Taguchi's signal to noise ratios to be effective over too narrow a range of applications and they are generally deprecated. For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ... Paul Samuelson, Nobel Prize in Economics winner. ... In statistics, mean has two related meanings: the average in ordinary English, which is also called the arithmetic mean (and is distinguished from the geometric mean or harmonic mean). ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ...

Off-line quality control

Taguchi realised that the best opportunity to eliminate variation is during design of a product and its manufacturing process (Taguchi's rule for manufacturing). Consequently, he developed a strategy for quality engineering that can be used in both contexts. The process has three stages:

1. System design;
2. Parameter design; and
3. Tolerance design.

System design

This is design at the conceptual level involving creativity and innovation. Look up Creativity in Wiktionary, the free dictionary. ...

Parameter design

Once the concept is established, the nominal values of the various dimensions and design parameters need to be set, the detail design phase of conventional engineering. Taguchi's radical insight was that the exact choice of values required is under-specified by the performance requirements of the system. In many circumstances, this allows the parameters to be chosen so as to minimise the effects on performance arising from variation in manufacture, environment and cumulative damage.

Tolerance design

With a successfully completed parameter design, and an understanding of the effect that the various parameters have on performance, resources can be focused on reducing and controlling variation in the critical few dimensions (see Pareto principle). The Pareto principle (also known as the 80-20 rule, the law of the vital few and the principle of factor sparsity) states that for many phenomena, 80% of the consequences stem from 20% of the causes. ...

Design of experiments

Taguchi developed much of his thinking in isolation from the school of R. A. Fisher, only coming into direct contact in 1954. His framework for design of experiments is idiosyncratic and often flawed but contains much that is of enormous value. He made a number of innovations. Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a English statistician, evolutionary biologist, and geneticist. ... 1954 (MCMLIV) was a common year starting on Friday of the Gregorian calendar. ... The first statistician to consider a methodology for the design of experiments was Sir Ronald A. Fisher. ...

Outer arrays

Unlike the design of experiments work of R. A. Fisher, Taguchi sought to understand the influence that parameters had on variation, not just on the mean. He contended, as had W. Edwards Deming in his discussion of analytic studies, that conventional sampling is inadequate here as there is no way of obtaining a random sample of future conditions. In R. A. Fisher's work, variation between experimental replications is a nuisance that the experimenter would like to eliminate whereas, in Taguchi's thinking, it is a central object of investigation. The first statistician to consider a methodology for the design of experiments was Sir Ronald A. Fisher. ... Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a English statistician, evolutionary biologist, and geneticist. ... William Edwards Deming (October 14, 1900 - December 20, 1993) was an American statistician, college professor, author, and lecturer widely credited with improving production in the United States during World War II. However, Deming is perhaps best known for his work in Japan; where from 1950 onward he taught top management... Sampling is that part of statistical practice concerned with the selection of individual observations intended to yield some knowledge about a population of concern, especially for the purposes of statistical inference. ... In statistics, a simple random sample from a population is a sample chosen randomly, in which each member of the population has the same probability of being chosen. ... Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a English statistician, evolutionary biologist, and geneticist. ...

Taguchi's innovation was to replicate each experiment by means of an outer array, possibly an orthogonal array that seeks deliberately to emulate the sources of variation that a product would encounter in reality. This is an example of judgement sampling. Though statisticians following in the Shewhart-Deming tradition have embraced outer arrays, many academics are still skeptical. In mathematics, orthogonal is synonymous with perpendicular when used as a simple adjective that is not part of any longer phrase with a standard definition. ... In computer programming, a group of homogeneous elements of a specific data type is known as an array, one of the simplest data structures. ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ...

Later innovations in outer arrays resulted in 'compounded noise'. This involves combining a few noise factors to create two levels in the outer array. First, noise factors that drive output lower and second, noise factors that drive output higher. This still emulates the extremes of noise variation but with fewer test samples required.

Management of interactions

Many of the orthogonal arrays that Taguchi has advocated are saturated allowing no scope for estimation of interactions. This is a continuing topic of controversy. In experiments in which additional factors are not likely to interact with any of the other factors, a saturated array can be used. ... Estimation is the calculated approximation of a result which is usable even if input data may be incomplete, uncertain, or noisy. ... Interaction is a kind of action which occurs as two or more objects have an effect upon one another. ...

• Followers of Taguchi argue that the designs offer rapid results and that interactions can be eliminated by proper choice of quality characteristic and by transforming the data. That notwithstanding, a confirmation experiment offers protection against any residual interactions.

• Western statisticians argue that interactions are part of the real world and that Taguchi's arrays have complicated alias structures that leave interactions difficult to disentangle. George Box, and others, have argued that a more effective and efficient approach is to use sequential assembly.

A graphical depiction of a statistical interaction in which the extent to which experience impacts cost depends on decision time. ... A graphical depiction of a statistical interaction in which the extent to which experience impacts cost depends on decision time. ... A graphical depiction of a statistical interaction in which the extent to which experience impacts cost depends on decision time. ... George Edward Pelham Box, born 18 October 1919 in England, was one of the most influential statisticians of the 20th century and a pioneer in the area of design of experiments. ...

Analysis of experiments

Taguchi introduced many methods for analysing experimental results including novel applications of the analysis of variance and minute analysis. Little of this work has been validated by Western statisticians. In statistics, analysis of variance (ANOVA) is a collection of statistical models and their associated procedures which compare means by splitting the overall observed variance into different parts. ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ...

Assessment

Genichi Taguchi has made seminal and valuable methodological innovations in statistics and engineering, within the Shewhart-Deming tradition. His emphasis on loss to society; techniques for investigating variation in experiments and his overall strategy of system, parameter and tolerance design have been massively influential in improving manufactured quality worldwide. Much of his work was carried out in isolation from the mainstream of Western statistics and, while this may have facilitated his creativity, much of the technical detail of Taguchi methods and its benfits to experimentation and research is only now being studied in the West. A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ... Engineering is the application of scientific and mathematical principles to develop economical solutions to technical problems, creating products, facilities, and structures that are useful to people. ... A graph of a bell curve in a normal distribution showing statistics used in educational assessment, comparing various grading methods. ...

Honours

• Indigo Ribbon from the Emperor of Japan
• Willard F. Rockwell Medal of the International Technology Institute
• Honorary member of the Japanese Society of Quality Control
• Shewhart Medal of the American Society for Quality, (1995)

His Imperial Majesty, Emperor Akihito. ... Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... The Shewhart Medal, named in honour of Walter A. Shewhart, is awarded annually by the American Society for Quality for . ... American Society for Quality (ASQ), formerly known as American Society for Quality Control (ASQC), is a non-profit professional society comprised of almost 100,000 members who work in various aspects of the quality field (e. ... 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ...

External links

• Quality Resources
• Information on Genichi Taguchi at QualityGurus.com
• Photograph of Dr. Genichi Taguchi
• Robust Design Review
• Increase Your Web Site's Conversion Rate Using the Taguchi Method