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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] Males are usually shown on the left and females on the right ...
Epidemiological transition. Diagram showing sharp birth rate and death rate decreases between Time 1 and Time 4, the congruent increase in population caused by delayed birth rate decreases, and the subsequent re-leveling of population growth by Time 5. In demography and medical geography, epidemiological transition is a theory which "describes ...
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. [1][2] A useful summary of such data is the population pyramid.
The human sex ratio is the ratio of males to females in a population in the context of anthropology and demography. In humans, the natural sex ratio at birth is slightly biased towards the male sex. It is estimated to be about 1.05 [1] or 1.06 [2] or within a narrow range from 1.03 to 1.06 [3] males per female.
In demography, demographic transition is a phenomenon and theory which refers to the historical shift from high birth rates and high death rates to low birth rates and low death rates, as societies attain more technology, education (especially of women) and economic development. [1] The demographic transition has occurred in most of the world ...
On April 1, 2020, the United States had a population of 331,449,281, according to the 2020 United States census. [ 31 ] The following demographic statistics are from the CIA World Factbook estimated as of 2018 [update], [ 5 ] unless otherwise indicated. Graphs are unavailable due to technical issues.
A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. [2][3] However, many species deviate from an even sex ratio, either periodically or permanently. Examples include parthenogenic species, periodically mating ...
More than 20% of the population was age 65 or older. Less than 11% was nine years old or younger. Shares of older people that outsize shares of younger people could show a community in decline and ...