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World population pyramid from 1950 to projected in 2100 (UN, World Population Prospects 2017) A population pyramid (age structure diagram) or "age-sex pyramid" is a graphical illustration of the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically takes the shape of a pyramid when the population is growing. [1]
The following list of countries by age structure sorts the countries of the world according to the age distribution of their population. The population is divided into three groups: Ages 0 to 14 years: children. Ages 15 to 64 years: working population or adults. Over the age of 65: elderly, senior citizens.
It is the only index associated with the age distribution of a population. [1] Currently, the median age ranges from a low of about 18 or less in most Least Developed countries to 40 or more in most European countries, Canada, Cuba, Hong Kong, Japan, South Korea, Taiwan, and Thailand.
The dependency ratio is the age-population ratio of people who are normally not in the labor force (the dependent population, which includes those aged 0 to 14 and 65 and older) to those who are (the productive part, ages 15 to 64). It is used to gauge the strain on the populace that is productive.
It provides data about the sex and age distribution of the population in an accessible graphical format. [3] Another summary is called the life table. For a cohort of persons born in the same year, it traces and projects their life experiences from birth to death.
The Leslie matrix is a discrete, age-structured model of population growth that is very popular in population ecology named after Patrick H. Leslie. [1] [2] The Leslie matrix (also called the Leslie model) is one of the most well-known ways to describe the growth of populations (and their projected age distribution), in which a population is closed to migration, growing in an unlimited ...
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 ...
An example of using age class structure to learn about a population is a regular bell curve for the population of 1-5 year-old fish with a very low population for the 3-year-olds. An age class structure with gaps in population size like the one described earlier implies a bad spawning year 3 years ago in that species. [7]