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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]
Over the age of 65: elderly, senior citizens. The age structure of a country has a strong impact on society and the economy. If the proportion of 0–14-year-olds is very high, there may be a so-called youth bulge. If, on the other hand, the proportion of over 65 is very high, the social systems of a country can be heavily burdened.
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]
The bottom of the "age pyramid" widens first where children, teenagers and infants are here, accelerating population growth rate. The age structure of such a population is illustrated by using an example from the Third World today.
The stable age-structure is determined both by the growth rate and the survival function (i.e. the Leslie matrix). [5] For example, a population with a large intrinsic growth rate will have a disproportionately “young” age-structure. A population with high mortality rates at all ages (i.e. low survival) will have a similar age-structure.
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 ...
Age stratification could also be defined as a system of inequalities linked to age. In Western societies, for example, both the old and the young are perceived and treated as relatively incompetent and excluded from much social life. Age stratification based on an ascribed status is a major source inequality, and thus may lead to ageism. [2]
2.5 Age structure. 2.6 Cities. 3 Vital statistics. Toggle Vital statistics subsection. 3.1 Current vital statistics. 3.2 Total fertility rates by region.