John Gordon Skellam (1914-1979) was a

statistician A statistician is a person who works with Theory, theoretical or applied statistics. The profession exists in both the private sector, private and public sectors. It is common to combine statistical knowledge with expertise in other subjects, a ...

and

ecologist Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

, who discovered the Skellam distribution. Skellam was born in

Staffordshire Staffordshire (; postal abbreviation ''Staffs''.) is a Ceremonial counties of England, ceremonial county in the West Midlands (region), West Midlands of England. It borders Cheshire to the north-west, Derbyshire and Leicestershire to the east, ...

. He was educated at

Hanley Hanley is one of the Federation of Stoke-on-Trent, six towns that, along with Burslem, Longton, Staffordshire, Longton, Fenton, Staffordshire, Fenton, Tunstall, Staffordshire, Tunstall and Stoke-upon-Trent, amalgamated to form the City of Stoke- ...

High School where he won several scholarships including free admission to New College in Oxford. He was one of the most respected members of the British Region of the Biometric Society. In 1951, John G. Skellam developed the reaction-diffusion model of

invasion biology An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species t ...

. This model describes the dynamics of populations, which simultaneously develops and spreads, and provides that the invasion front moves with constant speed. He explained on the basis of habitation

muskrat The muskrat or common muskrat (''Ondatra zibethicus'') is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over various climates ...

introduced to

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

that only by chance the species may be in a place where it would have to grow. Skellam has provided a model that allows to take the dynamics of populations as a

random variable A random variable (also called random quantity, aleatory variable, or stochastic variable) is a Mathematics, mathematical formalization of a quantity or object which depends on randomness, random events. The term 'random variable' in its mathema ...

at any time t. Its stochastic form is much more flexible than previous deterministic equations.

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1914 births 20th-century British zoologists English statisticians Alumni of New College, Oxford 1979 deaths 20th-century English mathematicians People from Hanley, Staffordshire {{UK-statistician-stub

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