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The Demography of the World Population from 1950 to 2100. Data source: United Nations — World Population Prospects 2017. Demography (from Ancient Greek δῆμος (dêmos) 'people, society' and -γραφία (-graphía) 'writing, drawing, description') [1] is the statistical study of human populations: their size, composition (e.g., ethnic group, age), and how they change through the ...
Demographic statistics are measures of the characteristics of, or changes to, a population. Records of births, deaths, marriages, immigration and emigration and a regular census of population provide information that is key to making sound decisions about national policy.
Demographics of the United States; Population pyramid of the United States in 2023. Population: 340,110,988 (2024 estimate) [1] 331,449,281 (2020 census) [2] Density:
Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems.Population dynamics is a branch of mathematical biology, and uses mathematical techniques such as differential equations to model behaviour.
In the study of age-structured population growth, probably one of the most important equations is the Euler–Lotka equation.Based on the age demographic of females in the population and female births (since in many cases it is the females that are more limited in the ability to reproduce), this equation allows for an estimation of how a population is growing.
The model can also be written in the form of a differential equation: = with initial condition: P(0)= P 0. This model is often referred to as the exponential law. [5] It is widely regarded in the field of population ecology as the first principle of population dynamics, [6] with Malthus as the founder.
One of the most basic and milestone models of population growth was the logistic model of population growth formulated by Pierre François Verhulst in 1838. The logistic model takes the shape of a sigmoid curve and describes the growth of a population as exponential, followed by a decrease in growth, and bound by a carrying capacity due to ...
The index of dissimilarity is a demographic measure of the evenness with which two groups are distributed across component geographic areas that make up a larger area. A group is evenly distributed when each geographic unit has the same percentage of group members as the total population.