John Gordon Skellam
Encyclopedia
John Gordon Skellam was born in Staffordshire
Staffordshire
Staffordshire is a landlocked county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. Part of the National Forest lies within its borders...

 county
Counties of England
Counties of England are areas used for the purposes of administrative, geographical and political demarcation. For administrative purposes, England outside Greater London and the Isles of Scilly is divided into 83 counties. The counties may consist of a single district or be divided into several...

 in 1914, died during the summer of 1979. He was educated at Hanley High School where he won several scholarships including free admission to New College in Oxford
New College, Oxford
New College is one of the constituent colleges of the University of Oxford in the United Kingdom.- Overview :The College's official name, College of St Mary, is the same as that of the older Oriel College; hence, it has been referred to as the "New College of St Mary", and is now almost always...

. He was one of the most respected members of the British Region of the Biometric Society
International Biometric Society
The International Biometric Society is an international professional and academic society promoting the development and application of statistical and mathematical theory and methods in the biosciences....

.

He was a statistician and ecologist, discoverer of distribution called his surname.

In 1951, John G. Skellam develops reaction-diffusion
Reaction–diffusion system
Reaction–diffusion systems are mathematical models which explain how the concentration of one or more substances distributed in space changes under the influence of two processes: local chemical reactions in which the substances are transformed into each other, and diffusion which causes the...

 model of invasion biology
Invasion biology terminology
The need for a clearly defined and consistent invasion biology terminology has been acknowledged by many sources. Invasive species, or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats...

. 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
Muskrat
The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...

 introduced to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...


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
Random variable
In probability and statistics, a random variable or stochastic variable is, roughly speaking, a variable whose value results from a measurement on some type of random process. Formally, it is a function from a probability space, typically to the real numbers, which is measurable functionmeasurable...

 at any time t. Its stochastic form
Stochastic process
In probability theory, a stochastic process , or sometimes random process, is the counterpart to a deterministic process...

 is much more flexible than previous deterministic equations.

He was principal scientific officer and editor of the "Biometrics
Biometrics (Journal)
Biometrics is a journal that publishes articles on the application of statistics and mathematics to the biological sciences. It is published by the International Biometric Society....

", the official organ of Biometric Society
International Biometric Society
The International Biometric Society is an international professional and academic society promoting the development and application of statistical and mathematical theory and methods in the biosciences....

, an international association headquarters in London.

His two the most significant articles are
Skellam, J. G. 1946. The frequency distribution of the difference between two Poisson variates belonging to different populations. Journal of the Royal Statistical Society: Series A 109 (3): 296.

and
Skellam, J.G. 1951. Random dispersal in theoretical populations

Articles

.ppt versiom of "Random Dispersal in Theoretical Populations"
Articles indexed by Google

External links

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