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In probability and statistics, the log-logistic distribution (known as the Fisk distribution in economics) is a continuous probability distribution for a non-negative random variable. It is used in survival analysis as a parametric model for events whose rate increases initially and decreases later, as, for example, mortality rate from cancer ...
The Hubbert peak theory says that for any given geographical area, from an individual oil-producing region to the planet as a whole, the rate of petroleum production tends to follow a bell-shaped curve. It is one of the primary theories on peak oil. Choosing a particular curve determines a point of maximum production based on discovery rates ...
Ricker model. The Ricker model, named after Bill Ricker, is a classic discrete population model which gives the expected number N t+1 (or density) of individuals in generation t + 1 as a function of the number of individuals in the previous generation, [1] Here r is interpreted as an intrinsic growth rate and k as the carrying capacity of the ...
The species–area relationship is usually constructed for a single type of organism, such as all vascular plants or all species of a specific trophic level within a particular site. It is rarely if ever, constructed for all types of organisms if simply because of the prodigious data requirements. It is related but not identical to the species ...
Irruptive growth is a growth pattern over time, defined by a sudden rapid growth in the population of an organism. Irruptive growth is studied in population ecology. [1] Population cycles often display irruptive growth, but with a predictable pattern of subsequent decline. [2] It is a phenomenon typically associated with r-strategists .
The EC 50 relates to the Hill equation, which is a function of the agonist concentration, [A]: where E is the observed response or effect above baseline, and n, the Hill coefficient reflects the slope of the curve. [7] The EC 50 represents the point of inflection of the Hill equation, beyond which increases of [A] have less impact on E.
In an equation of the form y' = f ( x , y ), the isoclines are lines in the ( x , y) plane obtained by setting f ( x , y) equal to a constant. This gives a series of lines (for different constants) along which the solution curves have the same gradient. By calculating this gradient for each isocline, the slope field can be visualised; making it ...
1) where x n is a number between zero and one, which represents the ratio of existing population to the maximum possible population. This nonlinear difference equation is intended to capture two effects: reproduction , where the population will increase at a rate proportional to the current population when the population size is small, starvation (density-dependent mortality), where the growth ...