Historical demographyHistorical demography is the quantitative study of human population in the past. It is concerned with population size, with the three basic components of population change (fertility, mortality, and migration), and with population characteristics related to those components, such as marriage, socioeconomic status, and the configuration of families. The sources of historical demography vary according to the period and topics of the study.
Mortality rateMortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of deaths per 1,000 individuals per year; thus, a mortality rate of 9.5 (out of 1,000) in a population of 1,000 would mean 9.5 deaths per year in that entire population, or 0.95% out of the total.
Political demographyPolitical demography is the study of the relationship between politics and population change. Population change is driven by classic demographic mechanisms – birth, death, age structure, and migration. However, in political demography, there is always scope for assimilation as well as boundary and identity change, which can redraw the boundaries of populations in a way that is not possible with biological populations. Typically, political-demographic projections can account for both demographic factors and transitions caused by social change.
Population ageingPopulation ageing is an increasing median age in a population because of declining fertility rates and rising life expectancy. Most countries have rising life expectancy and an ageing population, trends that emerged first in developed countries but are now seen in virtually all developing countries. That is the case for every country in the world except the 18 countries designated as "demographic outliers" by the United Nations. The aged population is currently at its highest level in human history.
Income and fertilityIncome and fertility is the association between monetary gain on one hand, and the tendency to produce offspring on the other. There is generally an inverse correlation between income and the total fertility rate within and between nations. The higher the degree of education and GDP per capita of a human population, subpopulation or social stratum, the fewer children are born in any developed country. In a 1974 United Nations population conference in Bucharest, Karan Singh, a former minister of population in India, illustrated this trend by stating "Development is the best contraceptive.
Medieval demographyMedieval demography is the study of human demography in Europe and the Mediterranean during the Middle Ages. It estimates and seeks to explain the number of people who were alive during the Medieval period, population trends, life expectancy, family structure, and related issues. Demography is considered a crucial element of historical change throughout the Middle Ages. The population of Europe remained at a low level in the Early Middle Ages, boomed during the High Middle Ages and reached a peak around 1300, then a number of calamities caused a steep decline, the nature of which historians have debated.
Cohort (statistics)In statistics, epidemiology, marketing and demography, a cohort is a group of subjects who share a defining characteristic (typically subjects who experienced a common event in a selected time period, such as birth or graduation). Cohort data can oftentimes be more advantageous to demographers than period data. Because cohort data is honed to a specific time period, it is usually more accurate. It is more accurate because it can be tuned to retrieve custom data for a specific study.
Fertility and intelligenceThe relationship between fertility and intelligence has been investigated in many demographic studies. There is evidence that, on a population level, measures of intelligence such as educational attainment and literacy are negatively correlated with fertility rate in some contexts. However, genetic studies have shown no evidence for dysgenic effects in human populations. Theories about dysgenic and eugenic effects in human populations have historically been associated with scientific racism.
Demographics of the worldEarth has a human population of over 8 billion as of 2023, with an overall population density of 50 people per km2 (130 per sq. mile), excluding Antarctica. Nearly 60% of the world's population lives in Asia, with almost 2.8 billion in the countries of India and China combined. The percentage shares of India, China and rest of South Asia of the world population have remained at similar levels for the last few thousand years of recorded history. The world's literacy rate has increased dramatically in the last 40 years, from 66.
Gompertz functionThe Gompertz curve or Gompertz function is a type of mathematical model for a time series, named after Benjamin Gompertz (1779–1865). It is a sigmoid function which describes growth as being slowest at the start and end of a given time period. The right-side or future value asymptote of the function is approached much more gradually by the curve than the left-side or lower valued asymptote. This is in contrast to the simple logistic function in which both asymptotes are approached by the curve symmetrically.
