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**Karl Pearson** (March 27, 1857 – April 27, 1936) was a major contributor to the early development of statistics as a serious scientific discipline in its own right. He founded the Department of Applied Statistics at University College London in 1911; it was the first university statistics department in the world.

## Contents

## Biography

Karl Pearson was born in Islington, London on March 27, 1857, the son of barrister William Pearson and Fanny, née Smith. He was educated privately at University College School, after which he went to King's College, Cambridge to study mathematics. He then spent part of 1879 and 1880 studying medieval and 16th century German literature at the universities of Berlin and Heidelberg – in fact, he became sufficiently knowledgeable in this field that he was offered a post in the German department at Cambridge University.

His next career move was to Lincoln's Inn, where he read law until 1881 (although he never practised). After this, he returned to mathematics, deputising for the mathematics professor at King's College London in 1881 and for the professor at University College London in 1883. In 1884, he was appointed to the Goldsmid Chair of Applied Mathematics and Mechanics at University College London. 1891 saw him also appointed to the professorship of Geometry at Gresham College; here he met Walter Frank Raphael Weldon, a zoologist who had some interesting problems requiring quantitative solutions. The collaboration, in biometry and evolutionary theory, was a fruitful one and lasted until Weldon died in 1906. Weldon introduced Pearson to Charles Darwin's cousin Francis Galton, who was interested in aspects of evolution such as heredity and eugenics. Pearson became Galton's protégé — his "statistical heir" as some have put it — at times to the verge of hero worship. After Galton's death in 1911, Pearson embarked on producing his definitive biography—a three-volume tome of narrative, letters, genealogies, commentaries, and photographs—published in 1914, 1924, and 1930, with much of Pearson's own financing paying for their print runs. The biography, done "to satisfy myself and without regard to traditional standards, to the needs of publishers or to the tastes of the reading public", triumphed Galton's life, work, and personal heredity. He predicted that Galton, rather than Charles Darwin, would be remembered as the most prodigious grandson of Erasmus Darwin.

When Galton died, he left the residue of his estate to the University of London for a Chair in Eugenics. Pearson was the first holder of this chair, in accordance with Galton's wishes. He formed the Department of Applied Statistics (with financial support from the Drapers' Company), into which he incorporated the Biometric and Galton laboratories. He remained with the department until his retirement in 1933, and continued to work until his death in 1936.

Pearson married Maria Sharpe in 1890, and between them they had two daughters and a son. The son, Egon Sharpe Pearson, succeeded him as head of the Applied Statistics Department at University College.

When the 23 year-old Albert Einstein started a study group, the Olympia Academy, with his two younger friends, Solovine and Habicht, he suggested that the first book to be read was Pearson's *The Grammar of Science*. This book covered several themes that were later to become part of the theories of Einstein and other scientists. Pearson asserted that the laws of nature are relative to the perceptive ability of the observer. Irreversibility of natural processes, he claimed, is a purely relative conception. An observer who travels at the exact velocity of light would see an eternal now, or an absence of motion. He speculated that an observer who traveled faster than light would see time reversal, similar to a cinema film being run backwards. Pearson also discussed antimatter, the fourth dimension, and wrinkles in time.

Pearson's relativity was based on idealism, in the sense of ideas or pictures in a mind. "There are many signs," he wrote, "that a sound idealism is surely replacing, as a basis for natural philosophy, the crude materialism of the older physicists." (Preface to 2nd Ed., *The Grammar of Science*) Further, he stated, "...science is in reality a classification and analysis of the contents of the mind...." "In truth, the field of science is much more consciousness than an external world." (*Ibid.*, Ch. II, § 6) "Law in the scientific sense is thus essentially a product of the human mind and has no meaning apart from man." (*Ibid.*, Ch. III, § 4)

Aside from his professional life, Pearson was active as a prominent freethinker and socialist. He gave lectures on such issues as "the woman's question" (this was the era of the suffragist movement in the UK) and upon Karl Marx. His commitment to socialism and its ideals led him to refuse the offer of being created an OBE (Officer of the Order of the British Empire) in 1920, and also to refuse a Knighthood in 1935. In the 1930s he had a protracted feud with R.A. Fisher over a statistical disagreement, which continued after his death through his son.

Pearson's views on eugenics, however, would be considered deeply racist today. According to a BBC report on the history of genetics, "Pearson was a fanatic – a cold, calculating measurer of man who claimed to be a socialist, but loathed the working class." Pearson openly advocated "war" against "inferior races," and saw this as a logical implication of his scientific work on human measurement: "My view – and I think it may be called the scientific view of a nation," he wrote, "– is that of an organized whole, kept up to a high pitch of internal efficiency by insuring that its numbers are substantially recruited from the better stocks, and kept up to a high pitch of external efficiency by contest, chiefly by way of war with inferior races." He reasoned that, if August Weismann's theory of germ plasm is correct, then the nation is wasting money when it tries to improve people who come from poor stock. Weismann claimed that acquired characteristics could not be inherited. Therefore, training benefits only the trained generation. Their children will not exhibit the learned improvements and, in turn, will need to be improved. "No degenerate and feeble stock will ever be converted into healthy and sound stock by the accumulated effects of education, good laws, and sanitary surroundings. Such means may render the individual members of a stock passable if not strong members of society, but the same process will have to be gone through again and again with their offspring, and this in ever-widening circles, if the stock, owing to the conditions in which society has placed it, is able to increase its numbers." (Introduction, *The Grammar of Science*).

## Awards from professional bodies

Pearson achieved widespread recognition across a range of disciplines and his membership of, and awards from, various professional bodies reflects this:

- 1896: elected Fellow of the Royal Society
- 1898: awarded the Darwin Medal
- 1911: awarded the honorary degree of LLD from St Andrews University
- 1911: awarded a DSc from University of London
- 1920: offered (and refused) the OBE
- 1932: awarded the Rudolf Virchow medal by the Berliner Anthropologische Gesellschaft
- 1935: offered (and refused) a knighthood

He was also elected an Honorary Fellow of King's College Cambridge, the Royal Society of Edinburgh, University College London and the Royal Society of Medicine, and a Member of the Actuaries' Club.

## Contributions to statistics

Pearson's work was all-embracing in the wide application and development of mathematical statistics, and encompassed the fields of biology, epidemiology, anthropometry, medicine and social history. In 1901, with Weldon and Galton, he founded the journal *Biometrika* whose object was the development of statistical theory. He edited this journal until his death. He also founded the journal *Annals of Eugenics* (now *Annals of Human Genetics*) in 1925. He published the *Drapers' Company Research Memoirs* largely to provide a record of the output of the Department of Applied Statistics not published elsewhere.

Pearson's thinking underpins many of the 'classical' statistical methods which are in common use today. Some of his main contributions are:

**Linear regression and correlation.**Pearson was instrumental in the development of this theory. One of his classic data sets (originally collected by Galton) involves the regression of sons' height upon that of their fathers'. Pearson built a 3-dimensional model of this data set (which remains in the care of the Statistical Science Department) to illustrate the ideas. The Pearson product-moment correlation coefficient is named after him, and it was the first important effect size to be introduced into statistics.**Classification of distributions.**Pearson's work on classifying probability distributions forms the basis for a lot of modern statistical theory; in particular, the exponential family of distributions underlies the theory of generalized linear models.- Pearson's chi-square test. A particular kind of chi-square test, a statistical test of significance.

## Publications

*The New Werther*(1880)*The Trinity, A Nineteenth Century Passion Play*(1882)*Die Fronica*(1887)*The Ethic of Freethought*(1886)*The Grammar of Science*(1892), Dover Publications 2004 edition, ISBN 0486495817*On the dissection of asymmetrical frequency curves*(1894)*Skew variation in homogeneous material*(1895)*Regression, heredity and panmixia*(1896)*On the criterion that a given system of deviations from the probable in the case of a correlated system of variables is such that it can be reasonably supposed to hove arisen from random sampling*(1900)*Tables for Statisticians and Biometricians*((1914))*Tables of Incomplete Beta Function*(1934)*The life, letters and labours of Francis Galton*(3 vol.: 1914, 1924, 1930). Available in full at http://galton.org

## See also

- Kikuchi Dairoku, a close friend and contemporary of Karl Pearson at University College School and Cambridge University

## External links

- The MacTutor History of Mathematics archive at St. Andrews University includes biographies of mathematicians and statisticians (including Pearson), as well as general information on the history of mathematics.
- John Aldrich's Karl Pearson: a Reader's Guide contains many useful links to further sources of information.
- Gavan Tredoux's Francis Galton site, galton.org, contains Pearson's biography of Francis Galton, and several other papers - in addition to nearly all of Galton's own published works.

## Further reading

Most of the biographical information above is taken from *A list of the papers and correspondence of Karl Pearson (1857-1936)* held in the Manuscripts Room, University College London Library, compiled by M.Merrington, B.Blundell, S.Burrough, J.Golden and J.Hogarth and published by the Publications Office, University College London, 1983. See http://www.ucl.ac.uk/stats/history/pearson.html.

Further references which may be of use are:

- Porter, Theodore M. (2004):
*Karl Pearson: The Scientific Life in a Statistical Age*, Princeton University Press. - Eisenhart, Churchill (1974):
*Dictionary of Scientific Biography*, pp. 447–73. New York, 1974. - Filon, L. N. G. and Yule, G. U. (1936):
*Obituary Notices of the Royal Society of London*, Vol. ii, No. 5, pp. 73–110. - Pearson, E. S. (1938):
*Karl Pearson: An appreciation of some aspects of his life and work*. Cambridge University Press.

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