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Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world. The world's population is around 8,000,000,000 [3 ...
Urban density is a term used in urban planning and urban design to refer to the number of people inhabiting a given urbanized area. As such it is to be distinguished from other measures of population density. Urban density is considered an important factor in understanding how cities function. Research related to urban density occurs across ...
For example, say one wants to calculate with a calculator N 10, the population at the tenth generation, knowing N 0 the initial population and λ the finite rate of increase. With the last formula, the result is immediate by plugging t = 10, whether with the previous one it is necessary to know N 9, N 8, ..., N 2 until N 1. We can identify ...
Scrope's 1833 map of world population density, possibly the first dasymetric map. The earliest maps using this kind of approach include an 1833 map of world population density by George Julius Poulett Scrope [4] and an 1838 map of population density in Ireland by Henry Drury Harness, although the methods used to create these maps were never documented.
The physiological density or real population density is the number of people per unit area of arable land. A higher physiological density suggests that the available agricultural land is being used by more and may reach its output limit sooner than a country that has a lower physiological density. Egypt is a notable example, with physiological ...
Population density is an example of areal number density. The term number concentration (symbol: lowercase n , or C , to avoid confusion with amount of substance indicated by uppercase N ) is sometimes used in chemistry for the same quantity, particularly when comparing with other concentrations .
Allee effects are classified by the nature of density dependence at low densities. If the population shrinks for low densities, there is a strong Allee effect. If the proliferation rate is positive and increasing then there is a weak Allee effect. The null hypothesis is that proliferation rates are positive but decreasing at low densities.
The correlation reflects the noisiness and direction of a linear relationship (top row), but not the slope of that relationship (middle), nor many aspects of nonlinear relationships (bottom). N.B.: the figure in the center has a slope of 0 but in that case, the correlation coefficient is undefined because the variance of Y is zero.