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Demography () is the
statistical study A statistical hypothesis test is a method of statistical inference used to decide whether the data at hand sufficiently support a particular hypothesis. Hypothesis testing allows us to make probabilistic statements about population parameters. ...
of
population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
s, especially
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as
education Education is a purposeful activity directed at achieving certain aims, such as transmitting knowledge or fostering skills and character traits. These aims may include the development of understanding, rationality, kindness, and honesty ...
,
nationality Nationality is a legal identification of a person in international law, establishing the person as a subject, a ''national'', of a sovereign state. It affords the state jurisdiction over the person and affords the person the protection of the ...
,
religion Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...
, and ethnicity. Educational institutions usually treat demography as a field of
sociology Sociology is a social science that focuses on society, human social behavior, patterns of social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of empirical investigation an ...
, though there are a number of independent demography departments. These methods have primarily been developed to study human populations, but are extended to a variety of areas where researchers want to know how populations of social actors can change across time through processes of birth, death, and
migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
. In the context of
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
biological populations, demographic analysis uses administrative records to develop an independent estimate of the population. Demographic analysis estimates are often considered a reliable standard for judging the accuracy of the
census A census is the procedure of systematically acquiring, recording and calculating information about the members of a given population. This term is used mostly in connection with national population and housing censuses; other common censuses in ...
information gathered at any time. In the
labor force The workforce or labour force is a concept referring to the pool of human beings either in employment or in unemployment. It is generally used to describe those working for a single company or industry, but can also apply to a geographic reg ...
, demographic analysis is used to estimate sizes and flows of populations of workers; in
population ecology Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration. The discipline is import ...
the focus is on the birth, death, migration and immigration of individuals in a population of living organisms, alternatively, in social human sciences could involve movement of firms and institutional forms. Demographic analysis is used in a wide variety of contexts. For example, it is often used in business plans, to describe the population connected to the geographic location of the business. Demographic analysis is usually abbreviated as DA. For the 2010 U.S. Census, The U.S. Census Bureau has expanded its DA categories. Also as part of the 2010 U.S. Census, DA now also includes comparative analysis between independent housing estimates, and census address lists at different key time points. Patient demographics form the core of the data for any medical institution, such as patient and emergency contact information and patient medical record data. They allow for the identification of a patient and his categorization into categories for the purpose of statistical analysis. Patient demographics include:
date of birth A birthday is the anniversary of the birth of a person, or figuratively of an institution. Birthdays of people are celebrated in numerous cultures, often with birthday gifts, birthday cards, a birthday party, or a rite of passage. Many re ...
,
gender Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most cultures ...
, date of
death Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
, postal code, ethnicity, blood type, emergency contact information, family doctor, insurance provider data,
allergies Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermat ...
, major diagnoses and major medical history. Formal demography limits its object of study to the measurement of population processes, while the broader field of social demography or population studies also analyses the relationships between economic, social, institutional, cultural, and biological processes influencing a population.


History

Demographic thoughts traced back to antiquity, and were present in many civilisations and cultures, like
Ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
,
Ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
, China and
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. Made up of the prefix '' demo-'' and the suffix ''
-graphy The English suffix -graphy means a "field of study" or related to "writing" a book, and is an anglicization of the French ''-graphie'' inherited from the Latin ''-graphia'', which is a transliterated direct borrowing from Greek. Arts * Cartogr ...
'', the term ''
demography Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as edu ...
'' refers to the overall study of population. In ancient Greece, this can be found in the writings of
Herodotus Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer A geographer is a physical scientist, social scientist or humanist whose area of study is geography, the study of Earth's natural environment and human society ...
,
Thucydides Thucydides (; grc, , }; BC) was an Athenian historian and general. His '' History of the Peloponnesian War'' recounts the fifth-century BC war between Sparta and Athens until the year 411 BC. Thucydides has been dubbed the father of " scienti ...
,
Hippocrates Hippocrates of Kos (; grc-gre, Ἱπποκράτης ὁ Κῷος, Hippokrátēs ho Kôios; ), also known as Hippocrates II, was a Greek physician of the classical period who is considered one of the most outstanding figures in the history o ...
, Epicurus, Protagoras, Polus,
Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...
and
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
. In Rome, writers and philosophers like
Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the esta ...
,
Seneca Seneca may refer to: People and language * Seneca (name), a list of people with either the given name or surname * Seneca people, one of the six Iroquois tribes of North America ** Seneca language, the language of the Seneca people Places Extrat ...
,
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ' ...
,
Marcus Aurelius Marcus Aurelius Antoninus (Latin: áːɾkus̠ auɾέːli.us̠ antɔ́ːni.us̠ English: ; 26 April 121 – 17 March 180) was Roman emperor from 161 to 180 AD and a Stoic philosopher. He was the last of the rulers known as the Five Good ...
,
Epictetus Epictetus (; grc-gre, Ἐπίκτητος, ''Epíktētos''; 50 135 AD) was a Greek Stoic philosopher. He was born into slavery at Hierapolis, Phrygia (present-day Pamukkale, in western Turkey) and lived in Rome until his banishment, when ...
, Cato, and
Columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...
also expressed important ideas on this ground. In the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
, Christian thinkers devoted much time in refuting the Classical ideas on demography. Important contributors to the field were
William of Conches William of Conches (c. 1090/1091 – c. 1155/1170s) was a French scholastic philosopher who sought to expand the bounds of Christian humanism by studying secular works of the classics and fostering empirical science. He was a prominent member ...
,Peter Biller,''The measure of multitude: Population in medieval thought

Bartholomew of Lucca, William of Auvergne, William of Pagula, and Muslim sociologists like Ibn Khaldun. One of the earliest demographic studies in the modern period was ''Natural and Political Observations Made upon the Bills of Mortality'' (1662) by
John Graunt John Graunt (24 April 1620 – 18 April 1674) has been regarded as the founder of demography. Graunt was one of the first demographers, and perhaps the first epidemiologist, though by profession he was a haberdasher. He was bankrupted later in li ...
, which contains a primitive form of
life table In actuarial science and demography, a life table (also called a mortality table or actuarial table) is a table which shows, for each age, what the probability is that a person of that age will die before their next birthday ("probability of death ...
. Among the study's findings were that one-third of the children in
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
died before their sixteenth birthday. Mathematicians, such as
Edmond Halley Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, H ...
, developed the life table as the basis for life insurance mathematics.
Richard Price Richard Price (23 February 1723 – 19 April 1791) was a British moral philosopher, Nonconformist minister and mathematician. He was also a political reformer, pamphleteer, active in radical, republican, and liberal causes such as the French ...
was credited with the first textbook on life contingencies published in 1771, followed later by Augustus de Morgan, ''On the Application of Probabilities to Life Contingencies'' (1838). In 1755,
Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading inte ...
published his essay '' Observations Concerning the Increase of Mankind, Peopling of Countries, etc.'', projecting
exponential growth Exponential growth is a process that increases quantity over time. It occurs when the instantaneous rate of change (that is, the derivative) of a quantity with respect to time is proportional to the quantity itself. Described as a function, a ...
in
British colonies A Crown colony or royal colony was a colony administered by The Crown within the British Empire. There was usually a Governor, appointed by the British monarch on the advice of the UK Government, with or without the assistance of a local Coun ...
. His work influenced
Thomas Robert Malthus Thomas Robert Malthus (; 13/14 February 1766 – 29 December 1834) was an English cleric, scholar and influential economist in the fields of political economy and demography. In his 1798 book '' An Essay on the Principle of Population'', Ma ...
, who, writing at the end of the 18th century, feared that, if unchecked, population growth would tend to outstrip growth in food production, leading to ever-increasing famine and poverty (see
Malthusian catastrophe Malthusianism is the idea that population growth is potentially exponential while the growth of the food supply or other resources is linear, which eventually reduces living standards to the point of triggering a population die off. This event, c ...
). Malthus is seen as the intellectual father of ideas of
overpopulation Overpopulation or overabundance is a phenomenon in which a species' population becomes larger than the carrying capacity of its environment. This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scal ...
and the limits to growth. Later, more sophisticated and realistic models were presented by Benjamin Gompertz and Verhulst. In 1855, a
Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...
scholar Achille Guillard defined demography as the natural and social history of human species or the mathematical knowledge of populations, of their general changes, and of their physical, civil, intellectual, and moral condition. The period 1860–1910 can be characterized as a period of transition where in demography emerged from statistics as a separate field of interest. This period included a panoply of international ‘great demographers’ like
Adolphe Quetelet Lambert Adolphe Jacques Quetelet FRSF or FRSE (; 22 February 1796 – 17 February 1874) was a Belgian astronomer, mathematician, statistician and sociologist who founded and directed the Brussels Observatory and was influential in intro ...
(1796–1874),
William Farr William Farr CB (30 November 1807 – 14 April 1883) was a British epidemiologist, regarded as one of the founders of medical statistics. Early life William Farr was born in Kenley, Shropshire, to poor parents. He was effectively adopted b ...
(1807–1883), Louis-Adolphe Bertillon (1821–1883) and his son
Jacques Ancient and noble French family names, Jacques, Jacq, or James are believed to originate from the Middle Ages in the historic northwest Brittany region in France, and have since spread around the world over the centuries. To date, there are over ...
(1851–1922), Joseph Körösi (1844–1906), Anders Nicolas Kaier (1838–1919), Richard Böckh (1824–1907),
Émile Durkheim David Émile Durkheim ( or ; 15 April 1858 – 15 November 1917) was a French sociologist. Durkheim formally established the academic discipline of sociology and is commonly cited as one of the principal architects of modern social science, al ...
(1858–1917), Wilhelm Lexis (1837–1914), and
Luigi Bodio Luigi Bodio (born 12 October 1840 in Milan–2 November 1920 in Rome) was an Italian economist and statistician, among the founders of Italian Statistics. He was the first General Secretary of the International Statistical Institute (ISI) and am ...
(1840–1920) contributed to the development of demography and to the toolkit of methods and techniques of demographic analysis.


Methods

Demography is the statistical and mathematical study of the size, composition, and
spatial distribution A spatial distribution in statistics is the arrangement of a phenomenon across the Earth's surface and a graphical display of such an arrangement is an important tool in geographical and environmental statistics. A graphical display of a spatial d ...
of human populations and how these features change over time. Data are obtained from a census of the population and from registries: records of events like
birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
,
death Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
s, migrations, marriages,
divorce Divorce (also known as dissolution of marriage) is the process of terminating a marriage or marital union. Divorce usually entails the canceling or reorganizing of the legal duties and responsibilities of marriage, thus dissolving the ...
s, diseases, and employment. To do this, there needs to be an understanding of how they are calculated and the questions they answer which are included in these four concepts:
population change Population change is simply the change in the number of people in a specified area during a specific time period. Demographics (or demography) is the study of population statistics, their variation and its causes. These statistics include birth ra ...
, standardization of population numbers, the demographic bookkeeping equation, and population composition. There are two types of data collection—direct and indirect—with several methods of each type.


Direct methods

Direct data comes from vital statistics registries that track all births and deaths as well as certain changes in legal status such as marriage, divorce, and migration (registration of place of residence). In developed countries with good registration systems (such as the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
and much of
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
), registry statistics are the best method for estimating the number of births and deaths. A
census A census is the procedure of systematically acquiring, recording and calculating information about the members of a given population. This term is used mostly in connection with national population and housing censuses; other common censuses in ...
is the other common direct method of collecting demographic data. A census is usually conducted by a national government and attempts to enumerate every person in a country. In contrast to vital statistics data, which are typically collected continuously and summarized on an annual basis, censuses typically occur only every 10 years or so, and thus are not usually the best source of data on births and deaths. Analyses are conducted after a census to estimate how much over or undercounting took place. These compare the
sex ratio The sex ratio (or gender ratio) is usually defined as 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. Many species d ...
s from the census data to those estimated from natural values and mortality data. Censuses do more than just count people. They typically collect information about families or households in addition to individual characteristics such as age, sex, marital status, literacy/education, employment status, and occupation, and geographical location. They may also collect data on migration (or place of birth or of previous residence), language, religion, nationality (or ethnicity or race), and citizenship. In countries in which the vital registration system may be incomplete, the censuses are also used as a direct source of information about fertility and mortality; for example, the censuses of the
People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
gather information on births and deaths that occurred in the 18 months immediately preceding the census.


Indirect methods

Indirect methods of collecting data are required in countries and periods where full data are not available, such as is the case in much of the developing world, and most of
historical demography Historical 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 characteristi ...
. One of these techniques in contemporary demography is the sister method, where survey researchers ask women how many of their sisters have died or had children and at what age. With these surveys, researchers can then indirectly estimate birth or death rates for the entire population. Other indirect methods in contemporary demography include asking people about siblings, parents, and children. Other indirect methods are necessary in historical demography. There are a variety of demographic methods for modelling population processes. They include models of mortality (including the
life table In actuarial science and demography, a life table (also called a mortality table or actuarial table) is a table which shows, for each age, what the probability is that a person of that age will die before their next birthday ("probability of death ...
, Gompertz models, hazards models, Cox proportional hazards models, multiple decrement life tables, Brass relational logits),
fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...
(Hermes model, Coale-Trussell models,
parity progression ratios A parity progression ratios (PPR) is a measure commonly used in demography to study fertility. The PPR is simply the proportion of women with a certain number of children who go on to have another child. Calculating the PPR, also known as a_x, ...
), marriage (Singulate Mean at Marriage, Page model), disability (
Sullivan's method Sullivan's index also known as Disability Free Life Expectancy (DFLE) is a method to compute life expectancy free of disability. It is calculated by formula: Life expectancy - duration of disability Health expectancy calculated by Sullivan’s ...
, multistate life tables), population projections ( Lee-Carter model, the Leslie Matrix), and
population momentum Population momentum is a consequence of the demographic transition. Population momentum explains why a population will continue to grow even if the fertility rate declines. Population momentum occurs because it is not only the number of children per ...
( Keyfitz). The United Kingdom has a series of four national birth cohort studies, the first three spaced apart by 12 years: the 1946 National Survey of Health and Development, the 1958
National Child Development Study The National Child Development Study (NCDS) is a continuing, multi-disciplinary longitudinal study which follows the lives of 17,415 people born in England, Scotland and Wales from 17,205 women during the week of 3–9 March 1958. The results from ...
, the
1970 British Cohort Study The 1970 British Cohort Study (BCS70) is a continuing, multi-disciplinary longitudinal survey monitoring the development of babies born in the UK during the week of 5–11 April 1970. History Since the start of the BCS70, eight full sets of data h ...
, and the
Millennium Cohort Study The Millennium Cohort Study (MCS) is a longitudinal survey conducted by the Centre for Longitudinal Studies (CLS) at the University of London, following the lives of a sample of about 18,818 babies born in the UK in the year 2000–2001. His ...
, begun much more recently in 2000. These have followed the lives of samples of people (typically beginning with around 17,000 in each study) for many years, and are still continuing. As the samples have been drawn in a nationally representative way, inferences can be drawn from these studies about the differences between four distinct generations of British people in terms of their health, education, attitudes, childbearing and employment patterns. Indirect standardization is used when a population is small enough that the number of events (births, deaths, etc.) are also small. In this case, methods must be used to produce a standardized
mortality rate Mortality 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 d ...
(SMR) or standardized incidence rate (SIR).


Population change

Population change is analyzed by measuring the change between one population size to another.
Global population In demographics, the world population is the total number of humans currently living. It was estimated by the United Nations to have exceeded 8 billion in November 2022. It took over 200,000 years of human prehistory and history for the ...
continues to rise, which makes population change an essential component to demographics. This is calculated by taking one population size minus the population size in an earlier
census A census is the procedure of systematically acquiring, recording and calculating information about the members of a given population. This term is used mostly in connection with national population and housing censuses; other common censuses in ...
. The best way of measuring population change is using the intercensal percentage change. The intercensal percentage change is the absolute change in population between the censuses divided by the population size in the earlier census. Next, multiply this a hundredfold to receive a percentage. When this statistic is achieved, the population growth between two or more
nation A nation is a community of people formed on the basis of a combination of shared features such as language, history, ethnicity, culture and/or society. A nation is thus the collective Identity (social science), identity of a group of people unde ...
s that differ in size, can be accurately measured and examined.


Standardization of population numbers

For there to be a significant comparison, numbers must be altered for the size of the population that is under study. For example, the
fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime # she were ...
is calculated as the ratio of the number of births to women of childbearing age to the total number of women in this age range. If these adjustments were not made, we would not know if a nation with a higher rate of births or deaths has a population with more women of childbearing age or more births per eligible woman. Within the category of standardization, there are two major approaches: direct standardization and indirect standardization.


Common rates and ratios

* The crude
birth rate The birth rate for a given period is the total number of live human births per 1,000 population divided by the length of the period in years. The number of live births is normally taken from a universal registration system for births; populati ...
, the annual number of live births per 1,000 people. * The general
fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime # she were ...
, the annual number of live births per 1,000 women of childbearing age (often taken to be from 15 to 49 years old, but sometimes from 15 to 44). * The age-specific fertility rates, the annual number of live births per 1,000 women in particular age groups (usually age 15–19, 20–24 etc.) * The crude
death rate Mortality 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 de ...
, the annual number of deaths per 1,000 people. * The
infant mortality rate Infant mortality is the death of young children under the age of 1. This death toll is measured by the infant mortality rate (IMR), which is the probability of deaths of children under one year of age per 1000 live births. The under-five morta ...
, the annual number of deaths of children less than 1 year old per 1,000 live births. * The expectation of life (or
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...
), the number of years that an individual at a given age could expect to live at present mortality levels. * The
total fertility rate The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime # she were t ...
, the number of live births per woman completing her reproductive life, if her childbearing at each age reflected current age-specific fertility rates. * The replacement level fertility, the average number of children women must have in order to replace the population for the next generation. For example, the replacement level fertility in the US is 2.11.Introduction to environmental engineering and science by Masters and Ela, 2008, Pearson Education, chapter 3 * The gross reproduction rate, the number of daughters who would be born to a woman completing her reproductive life at current age-specific fertility rates. * The net reproduction ratio is the expected number of daughters, per newborn prospective mother, who may or may not survive to and through the ages of childbearing. * A stable population, one that has had constant crude birth and death rates for such a long period of time that the percentage of people in every age class remains constant, or equivalently, the
population pyramid 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 ...
has an unchanging structure. * A stationary population, one that is both stable and unchanging in size (the difference between crude birth rate and crude death rate is zero). A stable population does not necessarily remain fixed in size. It can be expanding or shrinking. Note that the crude death rate as defined above and applied to a whole population can give a misleading impression. For example, the number of deaths per 1,000 people can be higher in developed nations than in less-developed countries, despite standards of health being better in developed countries. This is because developed countries have proportionally more older people, who are more likely to die in a given year, so that the overall mortality rate can be higher even if the mortality rate at any given age is lower. A more complete picture of mortality is given by a
life table In actuarial science and demography, a life table (also called a mortality table or actuarial table) is a table which shows, for each age, what the probability is that a person of that age will die before their next birthday ("probability of death ...
, which summarizes mortality separately at each age. A life table is necessary to give a good estimate of life expectancy.


Basic equation regarding development of a population

Suppose that a country (or other entity) contains ''Populationt'' persons at time ''t''. What is the size of the population at time ''t'' + 1 ? :\text_ = \text_t + \text_t + \text_t Natural increase from time ''t'' to ''t'' + 1: :\text_t = \text_t - \text_t Net migration from time ''t'' to ''t'' + 1: :\text_t = \text_t - \text_t These basic equations can also be applied to subpopulations. For example, the population size of ethnic groups or nationalities within a given society or country is subject to the same sources of change. When dealing with ethnic groups, however, "net migration" might have to be subdivided into physical migration and ethnic reidentification ( assimilation). Individuals who change their ethnic self-labels or whose ethnic classification in government statistics changes over time may be thought of as migrating or moving from one population subcategory to another. More generally, while the basic demographic equation holds true by definition, in practice the recording and counting of events (births, deaths, immigration, emigration) and the enumeration of the total population size are subject to error. So allowance needs to be made for error in the underlying statistics when any accounting of population size or change is made. The figure in this section shows the latest (2004) UN (
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
)
WHO Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book '' Horton He ...
projections of
world population In demographics, the world population is the total number of humans currently living. It was estimated by the United Nations to have exceeded 8 billion in November 2022. It took over 200,000 years of human prehistory and history for th ...
out to the year 2150 (red = high, orange = medium, green = low). The UN "medium" projection shows world population reaching an approximate equilibrium at 9 billion by 2075. Working independently, demographers at the
International Institute for Applied Systems Analysis The International Institute for Applied Systems Analysis (IIASA) is an independent international research institute located in Laxenburg, near Vienna, in Austria. Through its research programs and initiatives, the institute conducts policy-o ...
in
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
expect world population to peak at 9 billion by 2070. Throughout the 21st century, the average age of the population is likely to continue to rise.


Science of population

Populations can change through three processes: fertility, mortality, and migration. Fertility involves the number of children that women have and is to be contrasted with
fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...
(a woman's childbearing potential). Mortality is the study of the causes, consequences, and measurement of processes affecting death to members of the population. Demographers most commonly study mortality using the
life table In actuarial science and demography, a life table (also called a mortality table or actuarial table) is a table which shows, for each age, what the probability is that a person of that age will die before their next birthday ("probability of death ...
, a statistical device that provides information about the mortality conditions (most notably the life expectancy) in the population. Migration refers to the movement of persons from a locality of origin to a destination place across some predefined, political boundary. Migration researchers do not designate movements 'migrations' unless they are somewhat permanent. Thus, demographers do not consider tourists and travellers to be migrating. While demographers who study migration typically do so through census data on place of residence, indirect sources of data including tax forms and labour force surveys are also important. Demography is today widely taught in many universities across the world, attracting students with initial training in social sciences, statistics or health studies. Being at the crossroads of several disciplines such as
sociology Sociology is a social science that focuses on society, human social behavior, patterns of social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of empirical investigation an ...
,
economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...
,
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evide ...
,
geography Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, an ...
,
anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of be ...
and
history History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well ...
, demography offers tools to approach a large range of population issues by combining a more technical quantitative approach that represents the core of the discipline with many other methods borrowed from social or other sciences. Demographic research is conducted in universities, in research institutes, as well as in statistical departments and in several international agencies. Population institutions are part of the CICRED (International Committee for Coordination of Demographic Research) network while most individual scientists engaged in demographic research are members of the
International Union for the Scientific Study of Population International Union for the Scientific Study of Population is an international union for the study of human population, which was founded in 1928. References External links Official website International scientific organizations ...
, or a national association such as the
Population Association of America The Population Association of America (PAA) is a non-profit scientific professional association dedicated to the study of issues related to population and demography. The PAA was established by Henry Pratt Fairchild and Frederick Osborn, with fu ...
in the United States, or affiliates of the Federation of Canadian Demographers in
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
.Fédération canadienne de démographie – Federation of Canadian Demographers
/ref>


Population composition

Population composition is the description of population defined by characteristics such as age,
race Race, RACE or "The Race" may refer to: * Race (biology), an informal taxonomic classification within a species, generally within a sub-species * Race (human categorization), classification of humans into groups based on physical traits, and/or s ...
, sex or
marital status Civil status, or marital status, are the distinct options that describe a person's relationship with a significant other. ''Married'', '' single'', ''divorced'', and ''widowed'' are examples of civil status. ''Civil status'' and ''marital stat ...
. These descriptions can be necessary for understanding the
social dynamics Social dynamics (or sociodynamics) is the study of the behavior of groups that results from the interactions of individual group members as well to the study of the relationship between individual interactions and group level behaviors. Overv ...
from historical and comparative research. This data is often compared using a
population pyramid 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 ...
. Population composition is also a very important part of historical research. Information ranging back hundreds of years is not always worthwhile, because the numbers of people for which data are available may not provide the information that is important (such as
population size In population genetics and population ecology, population size (usually denoted ''N'') is the number of individual organisms in a population. Population size is directly associated with amount of genetic drift, and is the underlying cause of effect ...
). Lack of information on the original data-collection procedures may prevent accurate evaluation of data quality.


Demographic analysis in institutions and organizations


Labor market

The demographic analysis of labor markets can be used to show slow population growth,
population aging Population 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 ...
, and the increased importance of immigration. The U.S. Census Bureau projects that in the next 100 years, the United States will face some dramatic demographic changes. The population is expected to grow more slowly and age more rapidly than ever before and the nation will become a nation of immigrants. This influx is projected to rise over the next century as new immigrants and their children will account for over half the U.S. population. These demographic shifts could ignite major adjustments in the economy, more specifically, in labor markets.


Turnover and in internal labor markets

People decide to exit organizations for many reasons, such as, better jobs, dissatisfaction, and concerns within the family. The causes of turnover can be split into two separate factors, one linked with the culture of the organization, and the other relating to all other factors. People who do not fully accept a culture might leave voluntarily. Or, some individuals might leave because they fail to fit in and fail to change within a particular organization.


Population ecology of organizations

A basic definition of population ecology is a study of the distribution and abundance of organisms. As it relates to organizations and demography, organizations go through various liabilities to their continued survival. Hospitals, like all other large and complex organizations are impacted in the environment they work. For example, a study was done on the closure of acute care hospitals in Florida between a particular time. The study examined effect size, age, and niche density of these particular hospitals. A population theory says that organizational outcomes are mostly determined by
environmental factor An environmental factor, ecological factor or eco factor is any factor, abiotic or biotic, that influences living organisms. Abiotic factors include ambient temperature, amount of sunlight, and pH of the water soil in which an organism lives. Bi ...
s. Among several factors of the theory, there are four that apply to the hospital closure example: size, age, density of niches in which organizations operate, and density of niches in which organizations are established.


Business organizations

Problems in which demographers may be called upon to assist business organizations are when determining the best prospective location in an area of a branch store or service outlet, predicting the demand for a new product, and to analyze certain dynamics of a company's workforce. Choosing a new location for a branch of a bank, choosing the area in which to start a new supermarket, consulting a bank
loan officer Loan officers evaluate, authorize, or recommend approval of loan applications for people and businesses. Most loan officers are employed by commercial banks, credit unions, mortgage companies, and related financial institutions. Mortgage loan offi ...
that a particular location would be a beneficial site to start a car wash, and determining what shopping area would be best to buy and be redeveloped in metropolis area are types of problems in which demographers can be called upon. Standardization is a useful demographic technique used in the analysis of a business. It can be used as an interpretive and analytic tool for the comparison of different markets.


Nonprofit organizations

These organizations have interests about the number and characteristics of their clients so they can maximize the sale of their products, their outlook on their influence, or the ends of their power, services, and beneficial works.


See also

*
Biodemography Biodemography is the science dealing with the integration of biological theory and demography. Overview Biodemography is a new branch of human (classical) demography concerned with understanding the complementary biological and demographic deter ...
*
Biodemography of human longevity Biodemography is a multidisciplinary approach, integrating biological knowledge (studies on human biology and animal models) with demographic research on human longevity and survival. Biodemographic studies are important for understanding the driv ...
*
Demographics of the world Earth has a human population of over 8 billion, 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 Ch ...
*
Demographic economics Demographic economics or population economics is the application of economic analysis to demography, the study of human populations, including size, growth, density, distribution, and vital statistics. Aspects Aspects of the subject include * m ...
*
Gompertz–Makeham law of mortality The Gompertz–Makeham law states that the human death rate is the sum of an age-dependent component (the Gompertz function, named after Benjamin Gompertz), which increases exponentially with age and an age-independent component (the Makeham ter ...
* Linguistic demography * List of demographics articles *
Medieval demography Medieval 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, fam ...
* National Security Study Memorandum 200 of 1974 *
NRS social grade The NRS social grades are a system of demographic classification used in the United Kingdom. They were originally developed by the National Readership Survey (NRS) to classify readers, but are now used by many other organisations for wider appl ...
* Political demography *
Population biology The term population biology has been used with different meanings. In 1971 Edward O. Wilson ''et al''. used the term in the sense of applying mathematical models to population genetics, community ecology, and population dynamics. Alan Hastings ...
* Population dynamics *
Population geography Population geography relates spatial variations in the distribution, composition, migration, and growth of populations to the terrain. Population geography involves demography in a geographical perspective. It focuses on the characteristics of po ...
* Population reconstruction *
Population statistics 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 decisio ...
*
Religious demography The world's principal religions and spiritual traditions may be classified into a small number of major groups, though this is not a uniform practice. This theory began in the 18th century with the goal of recognizing the relative levels of c ...
* Replacement migration *
Reproductive health Sexual and reproductive health (SRH) is a field of research, healthcare, and social activism that explores the health of an individual's reproductive system and sexual wellbeing during all stages of their life. The term can also be further de ...


Social surveys

*
Current Population Survey The Current Population Survey (CPS) is a monthly survey of about 60,000 U.S. households conducted by the United States Census Bureau for the Bureau of Labor Statistics (BLS). The BLS uses the data to publish reports early each month called the Em ...
(CPS) *
Demographic and Health Surveys The Demographic and Health Surveys (DHS) Program is responsible for collecting and disseminating accurate, nationally representative data on health and population in developing countries. The project is implemented by ICF International and is funded ...
(DHS) *
European Social Survey The European Social Survey (ESS) is a social scientific endeavour to map the attitudes, beliefs and behaviour patterns of the various populations in Europe. ESS is listed in the Registry of Research Data Repositories re3data.org. Prof Rory Fitzge ...
(ESS) *
General Social Survey The General Social Survey (GSS) is a sociological survey created and regularly collected since 1972 by the National Opinion Research Center at the University of Chicago. It is funded by the National Science Foundation. The GSS collects informa ...
(GSS) *
German General Social Survey The German General Social Survey (ALLBUS/GGSS - Die Allgemeine Bevölkerungsumfrage der Sozialwissenschaften) is a national data generation program in Germany, which is similar to the American General Social Survey (GSS). Its mission is to collect ...
(
ALLBUS The German General Social Survey (ALLBUS/GGSS - Die Allgemeine Bevölkerungsumfrage der Sozialwissenschaften) is a national data generation program in Germany, which is similar to the American General Social Survey (GSS). Its mission is to collect ...
) * Multiple Indicator Cluster Surveys (MICS) * National Longitudinal Survey (NLS) * Panel Study of Income Dynamics (PSID) * Performance Monitoring and Accountability 2020 (PMA2020) *
Socio-Economic Panel The ''German'' Socio-Economic Panel (SOEP [], for ''Sozio-oekonomisches Panel'') is a Longitudinal study, longitudinal panel dataset of the population in Germany. It is a household based study which started in 1984 and which reinterviews adul ...
(SOEP, German) *
World Values Survey The World Values Survey (WVS) is a global research project that explores people's values and beliefs, how they change over time, and what social and political impact they have. Since 1981 a worldwide network of social scientists have conducte ...
(WVS)


Organizations

*
Global Social Change Research Project The Global Social Change Research Project is a project devoted to bringing a clear understanding to the general public about social change. They have reports about social, political, economic, demographic and technological change throughout the worl ...
(United States) * Institut national d'études démographiques (INED) (France) *
Max Planck Institute for Demographic Research The Max Planck Institute for Demographic Research (MPIDR) is located in Rostock, Germany. It was founded in 1996 by James Vaupel and moved into new buildings in Rostock in 2002. It is one of approximately 80 institutes of the Max Planck Society. ...
(Germany) *
Office of Population Research The Office of Population Research (OPR) at Princeton University is the oldest population research center in the United States. Founded in 1936, the OPR is a leading demographic research and training center. Recent research activity has primarily f ...
(Princeton University) (United States) *
Population Council The Population Council is an international, nonprofit, non-governmental organization. The Council conducts research in biomedicine, social science, and public health and helps build research capacities in developing countries. One-third of its res ...
(United States) * Population Studies Center at the University of Michigan (United States) * Vienna Institute of Demography (VID) (Austria) * Wittgenstein Centre for Demography and Global Human Capital (Austria)


Scientific journals

* ''
Brazilian Journal of Population Studies Brazilian commonly refers to: * Something of, from or relating to Brazil * Brazilian Portuguese, the dialect of the Portuguese language used mostly in Brazil * Brazilians, the people (citizens) of Brazil, or of Brazilian descent Brazilian may al ...
'' * '' Cahiers québécois de démographie'' * ''
Demography Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as edu ...
'' * ''
Population and Development Review ''Population and Development Review'' is a quarterly peer-reviewed academic journal published by Wiley-Blackwell Wiley-Blackwell is an international scientific, technical, medical, and scholarly publishing business of John Wiley & Sons. It was f ...
''


References


Further reading

*
Josef Ehmer Josef Ehmer (* 7 November 1948 in Gschwandt) is an Austrian historian and professor emeritus at the University of Vienna. Education and academic career After attending elementary & secondary school in Upper Austria, Josef Ehmer studied history ...
, Jens Ehrhardt, Martin Kohli (Eds.)
''Fertility in the History of the 20th Century: Trends, Theories, Policies, Discourses''
Historical Social Research 36 (2), 2011. * Glad, John. 2008.
Future Human Evolution: Eugenics in the Twenty-First Century
'. Hermitage Publishers, * Gavrilova N.S., Gavrilov L.A. 2011. Ageing and Longevity: Mortality Laws and Mortality Forecasts for Ageing Populations n Czech: Stárnutí a dlouhověkost: Zákony a prognózy úmrtnosti pro stárnoucí populace Demografie, 53(2): 109–128. * Preston, Samuel, Patrick Heuveline, and Michel Guillot. 2000. ''Demography: Measuring and Modeling Population Processes''. Blackwell Publishing. * Gavrilov L.A., Gavrilova N.S. 2010. Demographic Consequences of Defeating Aging. Rejuvenation Research, 13(2-3): 329–334. *
Paul R. Ehrlich Paul Ralph Ehrlich (born May 29, 1932) is an American biologist known for his warnings about the consequences of population growth and limited resources. He is the Bing Professor Emeritus of Population Studies of the Department of Biology of St ...
(1968), ''
The Population Bomb ''The Population Bomb'' is a 1968 book co-authored by Stanford University Professor emeritus Paul R. Ehrlich and Stanford senior researcher emeritus in conservation biology Anne Howland Ehrlich. It predicted worldwide famine due to overpopulati ...
'' Controversial Neo-Malthusianist pamphlet * Leonid A. Gavrilov & Natalia S. Gavrilova (1991), ''The Biology of Life Span: A Quantitative Approach''. New York: Harwood Academic Publisher, *
Andrey Korotayev Andrey Vitalievich Korotayev (russian: link=yes, Андре́й Вита́льевич Корота́ев; born 17 February 1961) is a Russian anthropologist, economic historian, comparative political scientist, demographer and sociologist, ...
&
Daria Khaltourina Daria Andreyevna Khaltourina (russian: Дáрья Андрéевна Халтýрина; born 4 January 1979 in Chelyabinsk) is a Russian sociologist, anthropologist, demographer, and a public figure. She is the head of the Group of the Monitorin ...
(2006)
''Introduction to Social Macrodynamics: Compact Macromodels of the World System Growth''. Moscow: URSS


* Uhlenberg P. (Editor), (2009) International Handbook of the Demography of Aging, New York: Springer-Verlag, pp. 113–131. * Paul Demeny and Geoffrey McNicoll (Eds.). 2003. The Encyclopedia of Population. New York, Macmillan Reference USA, vol.1, 32-37 *
Phillip Longman Phillip Longman (born April 21, 1956, Stuttgart, Baden-Württemberg, West Germany) is a conservative American demographer. Presently he is a Schwartz Senior Fellow at the New America Foundation, and he formerly worked as a senior writer and dep ...
(2004), ''The Empty Cradle: how falling birth rates threaten global prosperity and what to do about it'' * Sven Kunisch, Stephan A. Boehm, Michael Boppel (eds) (2011). ''From Grey to Silver: Managing the Demographic Change Successfully'', Springer-Verlag, Berlin Heidelberg, * Joe McFalls (2007), ''Population: A Lively Introduction,''
Population Reference Bureau The Population Reference Bureau (PRB) is a private, nonprofit organization specializing in collecting and supplying statistics necessary for research and/or academic purposes focused on the environment, and health and structure of populations. The ...
br>
* Ben J. Wattenberg (2004), ''How the New Demography of Depopulation Will Shape Our Future''. Chicago: R. Dee, * Perry, Marc J. & Mackun, Paul J. ''Population Change & Distribution: Census 2000 Brief''. (2001) *Preston, Samuel; Heuveline,Patrick; and Guillot Michel. 2000. ''Demography: Measuring and Modeling Population Processes''. Blackwell Publishing. * Schutt, Russell K. 2006. "Investigating the Social World: The Process and Practice of Research". SAGE Publications. * Siegal, Jacob S. (2002), ''Applied Demography: Applications to Business, Government, Law, and Public Policy''. San Diego: Academic Press. * Wattenberg, Ben J. (2004), ''How the New Demography of Depopulation Will Shape Our Future''. Chicago: R. Dee,


External links


Quick demography data lookup
*
Historicalstatistics.org
Links to historical demographic and economic statistics
United Nations Population Division: Homepage
*

Population estimates and projections for 230 countries and areas *

Estimates and projections of urban and rural populations and urban agglomerations *

Probabilistic Population Projections, based on the 2010 Revision of the World Population Prospects.



* ttp://gsociology.icaap.org/report/demsum.html Brief review of world basic demographic trends
Family and Fertility Surveys
(FFS) {{Authority control Actuarial science Environmental social science Interdisciplinary subfields of sociology Human geography Market segmentation Human populations