Udny Yule

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This article is about the statistician. For other people with this name, see George Yule.

George Udny Yule
Yule distribution
Yule's Y
Yule's coefficient
Yule–Simpson effect
Yule–Walker equations
Preferential attachment
Simple birth process
AwardsGuy Medal (Gold, 1911)
Scientific career
FieldsStatistics, Genetics
InstitutionsUniversity College London, University of Cambridge

George Udny Yule

Yule distribution and proposing the preferential attachment model for random graphs.[2]

Personal life

Yule was born at Beech Hill, a house in

Cambridge, England. He came from an established Scottish family composed of army officers, civil servants, scholars, and administrators. His father, Sir George Udny Yule (1813–1886) was a brother of the noted orientalist Sir Henry Yule (1820–1889). His great uncle was the botanist John Yule.[3]

In 1899, Yule married May Winifred Cummings. The marriage was annulled in 1912, producing no children.[4]

Education and teaching

Udny Yule was educated at

Heinrich Rudolf Hertz, Yule returned to University College in 1893 to work as a demonstrator for Karl Pearson, one of his former teachers. Pearson was beginning to work in statistics and Yule followed him into this new field. Yule progressed to an assistant professorship but he left in 1899 to a better-paid position as secretary to an examination board, working under Philip Magnus at the City and Guilds Institute.[5]

In 1902 Yule became Newmarch lecturer in statistics at University College, a position he held together with his post at the City and Guilds Institute. He continued to publish articles and also wrote an influential textbook, Introduction to the Theory of Statistics (1911), based on his lectures.[5]

In 1912 Yule moved to

Ministry of Food
. A heart attack in 1931 left him semi-invalided and led to his early retirement. His flow of publications almost ceased but, in the 1940s he found new interests, one of which led to a book, The Statistical Study of Literary Vocabulary.

Scholarship

Yule was a prolific writer, the highlight of his publications being perhaps the

president
in 1924–26.

Yule's first paper on statistics appeared in 1895: "On the Correlation of Total Pauperism with Proportion of Out-relief". Yule was interested in applying statistical techniques to social problems and he quickly became a member of the

Mendelian theory of genetics
led to several papers.

In the 1920s Yule wrote three influential papers on

time series analysis, "On the time-correlation problem" (1921), a critique of the variate difference method, an investigation of a form of spurious correlation[7] (1926) and "On a Method of Investigating Periodicities in Disturbed Series, with Special Reference to Wolfer's Sunspot Numbers" (1927), which used an autoregressive model to model the sunspot time series instead of the established periodogram method of Schuster
.

Yule distribution

Figure from page 241 of Age and Area, by J. C. Willis. When plotted on a log-log plot, each of these curves become a straight line, indicating a power-law.

In 1922, J. C. Willis published Age and Area, based on botanical field work in Ceylon, where he studied the distributional patterns of the Ceylonese vascular plants in great detail. He compiled a table of the number of existent species in each genus of flowering plants, and the same for the Rubiaceae, and for the Chrysomelid beetles.

Let be the number of genera with existent species. When is plotted on a log-log plot, each of these follows a straight line. This shows that for some . That is, the distribution has a power-law tail. The figures are found in,[8] or [9] page 241 and 242.

A modern reproduction of the Yule diagram, using all genera of plants in the World Flora Online Plant List.[10]

In 1925 Yule published the paper "A Mathematical Theory of Evolution, based on the Conclusions of Dr. J. C. Willis, F.R.S.", where he proposed a stochastic process which reproduces the power-law tail.[2] This was later called the Yule process, but is now better known as preferential attachment.

Yule distribution
in his honour.

Assessment

Frank Yates culminated his 1952 obituary of Yule by saying:

“To summarize we may, I think, justly conclude that though Yule did not fully develop any completely new branches of statistical theory, he took the first steps in many directions which were later to prove fruitful lines for further progress… He can indeed rightly claim to be one of the pioneers of modern statistics”.[11]

Yule made important contributions to the theory and practice of

Yule distribution, a discrete power law
, is named after him.

Although Yule taught at Cambridge for twenty years, he had little impact on the development of statistics there. M. S. Bartlett recalled him as a "mentor" but his famous association with Maurice Kendall, who revised the Introduction to the Theory of Statistics, only came about after Kendall had graduated.

Selected works

References

  1. S2CID 178300526
    .
  2. ^
    S2CID 86079660
    .
  3. S2CID 178300526
    .
  4. ^ annulment: Yates, 1952
  5. ^
    doi:10.1093/ref:odnb/37086. (Subscription or UK public library membership
    required.)
  6. ISBN 978-1-932482-44-7
    .
  7. ^ "Why Do We Sometimes Get Nonsense Correlations between Time-series?" (PDF). Archived (PDF) from the original on 2 June 2016. Retrieved 20 November 2019.
  8. S2CID 4068702
    .
  9. ^ J C Willis (1 January 1922). Age and Area: A Study in Geographical Distribution and Origin of Species. Internet Archive. Cambridge University Press.
  10. doi:10.5281/zenodo.8079052
    , retrieved 14 July 2023
  11. ^ pioneer of modern statistics: Yates 1952, p. 320

External links

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