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Population distribution by age and sex for Angola in 2005. 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 most significant population planning system in the world was China's one-child policy, in which, with various exceptions, having more than one child was discouraged. Unauthorized births were punished by fines, although there were also allegations of illegal forced abortions and forced sterilization . [ 57 ]
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 ]
Population control is the practice of artificially maintaining the size of any population. It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a species from excessive rates of extinction, which is referred to as conservation biology. [1] [2] [3]
Population pyramid of Egypt in 2005. Many of those 30 and younger are educated citizens who are experiencing difficulty finding work. According to the Encyclopedia of International Development, the term demographic trap is used by demographers "to describe the combination of high fertility (birth rates) and declining mortality (death rates) in developing countries, resulting in a period of ...
The number of live births is normally taken from a universal registration system for births; population counts from a census, and estimation through specialized demographic techniques such as population pyramids. [clarification needed] The birth rate (along with mortality and migration rates) is used to calculate population growth. The ...
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 ...
[16] For example, in a closed system where immigration and emigration does not take place, the rate of change in the number of individuals in a population can be described as: = = = =, where N is the total number of individuals in the specific experimental population being studied, B is the number of births and D is the number of deaths per ...