Pearson , Karl

(1857–1936) British biometrician

Pearson, the son of a London lawyer, studied mathematics at Cambridge University. He then joined University College, London, initially (from 1884) as professor of applied mathematics and mechanics and from 1911 until his retirement in 1933 as Galton Professor of Eugenics.

Pearson's career was spent largely on applying statistics to biology. His interest in this derived ultimately from Francis Galton and was much reinforced by the work of his colleague Walter Weldon. In 1893 Weldon had argued that variation, heredity, and selection are matters of arithmetic; Pearson started in the 1890s to develop the appropriate ‘arithmetic’ or statistics as it came to be called. Between 1893 and 1906 Pearson published over a hundred papers on statistics in which such now familiar concepts as the standard deviation and the chi-square test for statistical significance were introduced. Later work was published in Biometrika, the journal founded by Pearson, Galton, and Weldon in 1901 and edited by Pearson until his death. This he ran with an unashamed partisanship, rejecting outright or correcting without invitation papers expressing views Pearson considered “controversial.” It is for this reason that Ronald Fisher, the most creative British statistician of the century, decided after receiving the treatment from Pearson in 1920 to publish elsewhere.

Pearson and Weldon became involved in an important controversy with William Bateson on the nature of evolution and its possible measurement. The biometricians emphasized the importance of continuous variation as the basic material of natural selection and proposed that it be analyzed statistically. Bateson and his supporters, whose views were reinforced by the rediscovery of the works of Gregor Mendel in 1900, attached more importance to discontinuous variation and argued that breeding studies are the best way to illuminate the mechanism of evolution.

The validity of Mendelism eventually became generally accepted. At the same time, however, the immense value of biometrical techniques in analyzing continuously variable characters like height, which are controlled by many genes, was also recognized. Following Weldon's death in 1906, Pearson spent less time trying to prove the biometricians' case and devoted himself instead to developing statistics as an exact science. He prepared and published many volumes of mathematical tables for statisticians. He also devoted much of his time to the study of eugenics, using Galton's data to issue various volumes of the Studies in National Deterioration (1906–24). In 1925 he founded and edited until his death the Annals of Eugenics.

To many Pearson is best known as the author of Grammar of Science (1892), a widely read positivist work on the philosophy of science in which he argued, like his earlier teacher Ernst Mach, that science does not explain but rather summarizes our experience in a convenient language.