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Census

Census

A census is the process of obtaining information about every member of a population (not necessarily a human population). It can be contrasted with sampling in which information is only obtained from a subset of a population. As such it is a method used for accumulating statistical data, and it is also vital to democracy (voting).

Ancient and medieval censuses

Rome conducted censuses to determine taxes (see Censor). The Bible relates stories of several censuses. The Book of Numbers describes a divinely-mandated census that occurred when Moses led the Israelites from Egypt. A later census called by King David of Israel, referred to as the "numbering of the people," incited divine retribution (for being militarily motivated or perhaps displaying lack of faith in God). A Roman census is also mentioned in one of the best known passages of the Bible in the Gospel of Luke. The world's oldest extant census comes from China during the Han Dynasty. Taken in the fall of 2 AD, it is considered by scholars to be quite accurate. At that time there were 57.5 million living in Han China, the world's largest population. The second oldest preserved census is also from the Han, dating back to 140 AD, when only a bit more than 48 million people were recorded. Mass migrations into what is today southern China are believed to be behind this massive demographic decline. In the Middle Ages, the most famous census is the Domesday Book, undertaken in 1086 by William I of England "to find out ... what or how much each landholder had in land and livestock, and what it was worth," so that he could properly tax the land he had recently conquered. In 1183, a census was taken of the crusader Kingdom of Jerusalem, to ascertain the number of men and amount of money that could possibly be raised against an invasion by Saladin, sultan of Egypt and Syria.

Modern censuses

Australia

The Australian census is run by the Australian Bureau of Statistics. It is carried out every five years, the last one being on August 7, 2001 and the next planned census is August 8, 2006.

Brazil

The Brazilian census is carried out by IBGE, the Brazilian Institute of Geography and Statistics, every 10 years. The last one was in 2000.

Canada

The Canadian census is run by Statistics Canada. The first census conducted in Canada was conducted in 1666, by French intendant Jean Talon, when he took a census to ascertain the number of people living in New France. In 1871, Canada's first formal census was conducted, which counted the population of Nova Scotia, Ontario, New Brunswick, and Quebec. In 1918, the Dominion Bureau of Statistics was formed. In 1971, Statistics Canada was formed to replace the Dominion Bureau of Statistics, and consequently, took over its census job. Censuses in Canada are conducted in five year intervals. The latest census was conducted in 2001 and the next planned census is 2006. Censuses taken in mid-decade (e.g. 1976, 1986, 1996, etc.) are referred to as quinquennial censuses. Others are referred to as decennial censuses. The first quinquennial census was conducted in 1956. See also: Canada 2001 Census

Costa Rica

Costa Rica carried out its 9th population census in 2000. INEC, National Institute of Statistics and Census is in charge of conduct these census. Past Costa Rican censuses were realized in 1864, 1883, 1892, 1927, 1950, 1963, 1973 and 1984.

Denmark

The first Danish census was in 1700-1701, and contained statistical information about adult men. Only about half of it still exists. A census of school children was taken during the 1730s. Following these early undertakings, the first census to attempt completely covering all citizens (including women and children who had previously been listed only as numbers) of Denmark-Norway was taken in 1769 [http://www.rhd.uit.no/census/ft1769.html]. At that point there were 797 584 citizens in the kingdom. Georg Christian Oeder took a statistical census in 1771 which covered Copenhagen, Sjælland, Møn, and Bornholm. After that, censuses followed somewhat regularly in 1787, 1801, and 1834, and between 1840 and 1860, the censuses were taken every five years, and then every ten years until 1890. Special censuses for Copenhagen were taken in 1885 and 1895. In the 20th century, censuses were taken every five years from 1901 to 1921, and then every ten years from 1930. The last census was taken in 1950. Currently, Det Centrale Personregister is doing the censuses using their register of Danish citizens. It is possible to search a portion of the Danish censuses online at [http://ddd.dda.dk/ Dansk Demografisk Database], and also view scanned versions at [http://www.arkivalieronline.dk/ Arkivalier Online].

France

Napoleon Bonaparte began the census in France as a means of determining the number of potential soldiers under his rule. Today, the census in France is carried out by INSEE. Since 2004, a partial census is carried out every year, and the results published as averages over 5 years.

Germany

The first large-scale census in the German Empire took place in 1895. Attempts at introducing a census in Germany sparked strong popular resentment in the 1980s since many quite personal questions were asked. Some campaigned for a boycott. In the end the Constitutional Court stopped the census in 1980 and 1983. The last census was in 1987. Germany has since used population samples in combination with statistical methods, in place of a full census.

Greece

Census takes place every 10 years and is carried out by the National Statistical Service of Greece [http://www.statistics.gr]. Last census was in 2001.

India

The decennial census of India is the primary source of information about the demographic characteristics of the population of India which is the second biggest country of the world in terms of population. The first census in India is dated 1872. It started as far back as in 1860 and was finished in 1871. Starting from there, a population census has been carried out every 10 years, latest being the fourteenth in February - March 2001. Census is carried out by the office of the Registrar General and Census Commissioner, India, Delhi under the Census of India Act, 1948. The act gives Central Government many powers like to notify a date for Census, power to ask for the services of any citizen for census work. The law makes it compulsory for every citizen to answer the census questions truthfully. The Act provides penalties for giving false answer or not giving answers at all to the census questionnaire. One of the most important provisions of law is the guarantee for the maintenance of secrecy of the information collected at the census of each individual. The census records are not open to inspection and also not admissible in evidence. Census happens in two phases, first House Listing and House Numbering Operations and second actual population enumeration phase. Census is carried out by the canvassing method. In this method, each and every household is visited and the information is collected by a specially trained enumerator. 9th February 2001, the first day of the 2001 census was celebrated as the census day.

Source

- [http://www.censusindia.net/ Website of the office of the Registrar General and Census Commissioner, India]
- [http://www.unfpa.org/sustainable/docs.htm Banthia J.K., Ex Registrar General & Census Commissioner, India. "Mobilising Support for India’s Census - Constraints and Challenges"]

Italy

The census in Italy is carried out by ISTAT every 10 years. The last four were in 1971, 1981, 1991, 2001.

Japan

Japan collects census information every five years. The figures show the English translation of the 2005 census form. The form solicits information on name, sex, relationship to head of household, year and month of birth, marital status, nationality, number of members of household, type and nature of dwelling, floor area of dwelling, number of hours worked during the week prior to October 1, employment status, name of employer and type of business, and kind of work. Image:CensusSide1.png|Explanation of census form, side 1 Image:CensusSide2.png|Explanation of census form, side 2

Latvia

The most recent census in Latvia was in 2000. Before that, it was about 6 censuses, most part of these previous censuses was in the USSR time. The census in Latvia is carried out by Centrālā Statistikas Pārvalde (Central Statistical Bureau).

New Zealand

The census in New Zealand is carried out by Statistics New Zealand (Te Tari Tatau), every five years. The last was in 2001, the next will be in 2006. See New Zealand Census of Population and Dwellings.

Poland

The census in Poland is carried out by GUS every circa 10 years. The last one occurred in 2002.

Portugal

The census in Portugal is carried out by INE every 10 years. The last one occurred in 2001.

Romania

The first census in Romania was carried out in 1859. Nowadays it is carried every ten years by the Institutul Naţional de Statistică (INSSE). The last one occurred in 2002.

Russia/USSR

In Russia, the first All-Russia Population Census was carried out in 1897. All-Union Population Censuses were carried out in the USSR (which included RSFSR and the other republics) in 1920, 1926, 1939, 1959, 1970, 1979, and 1989). The first (post-Soviet) All-Russia Population Census was carried out in 2002. Next census is tentatively planned for 2010. Currently, the census is the responsibility of the [http://www.gks.ru Federal State Statistics Service.]

South Africa

The census in South Africa is carried out every 5 years by Statistics South Africa. The only two to date were in 1996 and 2001.

Ukraine

The first post-soviet census in Ukraine was carried out by [http://www.ukrcensus.gov.ua/eng/ State Statistics Committee of Ukraine] in 2001, 12 years after the last All-Union census in 1989.

United Kingdom

In the 7th century, Dalriada (now Scotland) was the first territory in what is now the UK to conduct a census, with what was called the "Tradition of the Men of Alba" (Senchus fer n'Alba'). England took its first Census when the Domesday Book was compiled in 1086 for tax purposes. The UK census as we know it today started in 1801 (championed by John Rickman who managed the first four up to 1831), partly to ascertain the number of men able to fight in the Napoleonic wars. Rickman's 12 reasons - set out in 1798 and repeated in Parliamentary debates - for conducting a UK census included the following justifications:
- 'the intimate knowledge of any country must form the rational basis of legislation and diplomacy'
- 'an industrious population is the basic power and resource of any nation, and therefore its size needs to be known'
- 'the number of men who were required for conscription to the militia in different areas should reflect the area's population'
- 'there were defence reasons for wanting to know the number of seamen'
- 'the need to plan the production of corn and thus to know the number of people who had to be fed'
- 'a census would indicate the Government's intention to promote the public good' and
- 'the life insurance industry would be stimulated by the results.' The census has been conducted every ten years since 1801 and most recently in 2001. The first four censuses (1801-1831) were mainly statistical (that is, they were mainly headcounts and contained virtually no personal information). The 1841 Census was the first to record names of all individuals in a household or institution. Because of World War II, there was no census in 1941. However, following the passage into law (on 5 September 1939) of the National Registration Act a population count was carried out on 29 September 1939, which was, in effect, a census. The census is undertaken by the government for policy and planning purposes, and the (statistical) information is also sold to interested parties. Public access to the census returns is restricted under the terms of the 100-year rule and the most recent returns made available to researchers are those of the 1901 Census. The census is usually very accurate, and with a fine of up to £1,000 for those who do not complete it, filled in by a high percentage of the population. An exception may have been the census conducted during the years of the poll tax (1991), when some people avoided it in case it was used for enforcing the tax. The 2001 census was the first year in which the government asked about religion. Perhaps encouraged by a chain letter that started in New Zealand, 390,000 people entered their religion as Jedi Knight (more than either Sikhs, Buddhists or Jews), with some areas registering up to 2.6% of people as Jedi.

United States

The United States Constitution mandates that the census be taken at least once every ten years (U.S. Congress could require a more frequent census by legislation), and that the number of members of the House of Representatives from each state be determined accordingly. In addition, Census Bureau statistics are used for apportioning Federal funding for many social and economic programs. But there is not a federal census legislation (nor for federal voting). The first U.S. Census was taken in 1790 by the local U.S. Marshals. Census-takers went door-to-door and recorded the number of people in each household, and the name of the head of the household. Slaves were counted, but for apportionment purposes each counted as only three-fifths of a citizen. American Indians being neither taxed nor considered during apportionment, were not counted. The first census counted 3.9 million people, less than half the population of New York City in 2000. The 2000 census counted over 281 million people. In 1902, a Public Law established the Census Bureau as a permanent Federal agency. Until the 2010 census, there were two forms of questionnaire – long and short. Currently, the plan is to replace the Long form in 2010 with the American Community Survey (ACS), but funding for ACS is not assured, in which case there may be a long form in the 2010 census. Computer algorithms (based on complex sampling rules) determine which form was mailed to a given household (in practice, of those households whose locations are on the Census Master Address List), one in six receiving the long form. This was supplemented by census workers who go door-to-door to talk to people who fail to return the forms. In addition to a simple count of residents, the Census Bureau collects a variety of statistics, on topics ranging from ethnicity to the presence of indoor plumbing. While some critics claim that census questions are an invasion of privacy, the data collected by every question is either required to enforce some federal law (such as the Voting Rights Act) or is required to administer some federal program. Congress gives approval to every question asked on the Census. Despite a massive effort, the Census Bureau has never been able to count every individual, leading to controversy about whether to use statistical methods to supplement the numbers for some purposes, as well as arguments over how to improve the actual head count. The Supreme Court has ruled that only an actual head count can be used to apportion Congressional seats; however, cities and minority representatives have complained that urban residents and minorities are undercounted. In several cases, the Census Bureau will recount an area with disputed figures, provided the local government pays for the time and effort. The State of Utah protested the figures of the 2000 decennial census because it lost a seat in the House of Representatives to North Carolina. Had the Census Bureau been able to count the numbers of Utahns living overseas, including many Mormon missionaries, Utah would have retained the seat. To minimize the burden on individuals and to provide improved data, the Bureau is preparing several alternative methods for gathering economic, demographic, and social information, including the American Community Survey and record linking of depersonalized administrative records with other administrative records and Census Bureau surveys. By law (92 Stat. 915, Public Law 95-416, enacted on October 5, 1978), census records are sealed for 72 years; in an era when life expectancy was under 60 years, this attempts to protect individual's privacy by prohibiting the release of such information during their expected lifetimes. Thus, the most recent Census released to the public was the 1930 Census, released in 2002. Indexes to some of the U.S. Censuses have been produced over the years, making the process of searching old census records much easier. Some indexes of census records have been produced by amateur volunteer genealogists. Due to the sheer volume of information, and the manual methodologies involved, the indexing used to be limited to the head-of-household. These indexes were published in bound volumes and are often available in regional libraries along with microfilm rolls that can be researched. While valuable, indexes produced from these censuses can be problematic to use. The original census records from this era were completed by hand by census enumerators; this leads to problems in handwriting recognition and variations in spelling of surnames within the original documents. The 1880 to 1920 censuses have indexes of last names, produced using the Soundex system; the indexing project was performed by the Works Progress Administration. The Soundex system is tolerant of variations in spelling; names with similar sounds but different spellings have the same encoding. The chief motivation in producing the Soundex name indexes was to assist citizens in finding census records to provide evidence of age, especially for those born before the advent of governmentally-approved birth certificates. (Verification of age was needed to establish eligibility for old-age benefits such as Social Security). Partial Soundex indexes of the 1930 census are available; resources from the Works Progress Administration were diverted towards support of World War II efforts before the project was completed. With the advent of computers, and more recently, the Internet, expanded indexes including all family members are beginning to appear on genealogy websites. These are accompanied with hypertext links that take the researcher directly to an image of the original census page, without having to travel to a regional library and scroll through endless rolls of microfilm. Genealogists view censuses as secondary sources of information; primary sources of information such as birth certificates are viewed as more reliable. Still, census information often provides useful information for genealogists and clues on where to proceed to find further primary source documents.

Local

In additional to the decennial federal census, more localized versions are often used. An example of this is Massachusetts, which takes a statewide census every fifth year. Likewise, each community in Massachusetts takes a municipal census each year. Category:Population

Sources

- [http://www.census.gov/Press-Release/www/releases/archives/miscellaneous/000507.html U.S. Census Press Release on 1930 Census]
- [http://www.archives.gov/publications/prologue/spring_2002_soundex_projects.html U.S. Census Press Release on Soundex and WPA]
- Bielenstein, Hans. "Wang Mang, the restoration of the Han dynasty, and Later Han." In The Cambridge History of China, vol. 1, eds. Denis Twitchett and John K. Fairbank, 223-90 (Cambridge: Cambridge University Press, 1978).

External links

- [http://www.archives.gov/genealogy/census/ Census at the U.S. National Archives]
- [http://www.censusfinder.com Census Finder - Links to census records online for the U.S., UK and Canada]
- [http://www.histpop.org Online Historical Population Reports Project (OHPR)]
- [http://statbel.fgov.be/census/links_en.asp Links to the official websites of various national censuses] Category:Data collection ko:인구 조사 ja:国勢調査 simple:Census

Population

] :For the use of the word population in statistics, see statistical population. In sociology and biology, a population is the collection of people, or organisms of a particular species, living in a given geographic area. In biology, plant and animal populations are studied, in particular, in a branch of ecology known as population biology, and in population genetics. In population dynamics, size, age and sex structure, mortality, reproductive behaviour, and growth of a population are studied. In biology, an isolated population denotes a breeding group whose members breed mostly or solely among themselves, usually as a result of physical isolation, although biologically they could breed with any members of the species. Meta-population is a group of sub-populations in a given area, where the individuals of the various sub-populations are able to cross uninhabitable areas of the region. Biological dispersal is one of the key elements affecting in such populations. Demography is the study of human populations. Various aspects of human behavior in populations are studied in sociology, economics, and geography. Study of populations is almost always governed by the laws of probability, and the conclusions of the studies may thus not always be applicable to some individuals. This odd factor may be reduced by statistical means, but such a generalization may be too vague to imply anything. Demography is used extensively in marketing, which relates to economic units, such as retailers, to potential customers. For example, Starbucks, a coffee shop company that wants to sell to a younger audience, looks at the demographics of an area to be able to appeal to this younger audience.

Population density

coffee Population density is measured by dividing the number of individuals by the area of the region in which they live. Some observers of human societies believe that the concept of carrying capacity also applies to the human population of the Earth, and that unchecked population growth can result in a "Malthusian catastrophe." Others dispute this view. The graph to the right depicts logistic growth of population. Populate, as a verb, means the process of populating a geographic area, as by procreation or immigration. The countries with the highest population density are microstates: Monaco, Singapore, the Vatican City, and Malta. Among larger-sized countries, Japan has one of the highest population densities.

Population pyramid

Japan The age and gender distribution of a population within a given nation or region is commonly represented by means of a population pyramid. This is a triangular distribution with the portion of the population along the horizontal X-axis and the 5-year age grouping along the vertical Y-axis. Male population is shown to the left of the vertical axis and female to the right. This type of chart displays the development of a population over a period of time. Nations with low infant mortality and high longevity will display a more rectangular shape as a majority of the population living to old age. The converse will have a more pyramidal shape with a wide base, reflecting higher infant mortality and greater risk of early death.

Underpopulation

In biology, a rarely occurring situation in which a group of individuals of a species appear in a new, inhabitable area suitable for more individuals, and begin to populate it. This may also happen if individuals of a species have been transferred to new areas on purpose or by accident. Ecological niches are usually populated, but evolution of a species may enable it to overcome the difficulties encountered in an initially hostile environment.

Overpopulation

evolution The world's human population is currently growing by more than 75 million people per year. About half the world lives in nations with sub-replacement fertility, and population growth in those countries is due to immigration. Overpopulation can result from increases in births and survival rates, or from an unsustainable use and depletion of resources. Advances in technology can reduce the threat of overpopulation by making new resources available, or by increasing the productivity of existing resources. In biology, a classic example of an overpopulation are the lemmings in Lapland, which procreate over the years to such densities, that a great part of the population is forced to wander to inhospitable areas. Nowadays, this happens usually in less dramatic ways than in the past, one reason probably being that the food supply of lemmings is shared with an increased number of reindeer in Lapland.

Population control

Population control is the practice of curtailing population increase, usually by reducing the birth rate. Surviving records from Ancient Greece document the first known examples of population control. These include the colonization movement, which saw Greek outposts being built across the Mediterranean and Black Sea basins to accommodate the excess population of individual states. An important example of mandated population control is China's one-child policy, in which having more than one child is made extremely unattractive. This has led to allegations that practices like infanticide, forced abortions, and forced sterilization are used as a result of the policy. In ecology, population control is on occasions considered to be done solely by predators, diseases, parasites, and environmental factors, though at many times human effects on animal and plant populations are also considered. Migrations of animals may be seen as a natural way of population control, for the food on land is more abundant on some seasons. The area of the migrations' start is left to reproduce the food supply for large mass of animals next time around. See also immigration.

Population decline

Population decline is a fall in a region's population. It can be caused by sub-replacement fertility or heavy emigration, or more dramatically disease, famine, or war. Or most often by a combination of the factors. In the past population decline was mostly observed due to disease. In recent years, the population of Russia and seventeen other ex-Communist countries has begun to decline (1995-2005). The Black Death in Europe, the arrival of Old World diseases to the Americas, or the Irish Potato Famine (1845-1849), all caused massive population declines. In biology, population decline of a species is usually described as a result of gradually worsening environmental factors, such as prolonged drought or loss of inhabitable areas for the studied species.

Population ageing

Population ageing occurs when the fertility rate declines. This means that, for a period of time, the ratio of old to young will be higher than average. It also occurs due to increasing life expectancy. Japan and Western Europe are the two regions which are most confronted by severe population ageing in the near future. The second largest expenditure of most governments is education and these expenses will fall with an ageing population. However older people tend to be the section of the population most concerned about crime and most insistent on more (and more expensive) law and order.

Population transfer

biological aspects, see introduced species Population transfer is a term referring to a policy by which a state forces the movement of a large group of people out of a region, most frequently on the basis of their ethnicity or religion. This has occured in India and Pakistan, between Turkey and Greece, and in Eastern Europe after the Second World War. Other movements in population are caused by immigration, such as the immigration from Europe to European colonies in the Americas, Africa, Australia and other places.

Population bomb

A best-selling work, The Population Bomb (1968) by Paul R. Ehrlich predicted disaster for humanity due to overpopulation and the "population explosion". A "population bomb," as defined in the book, requires three things: a rapid rate of change; a limit of some sort; and delays in perceiving the limit. The book's specific prediction that "in the 1970s and 1980s hundreds of millions of people will starve to death" did not come to pass, however, due for the most part to the efforts of Norman Borlaug's "Green Revolution" of the 1960s. It was later shown by Keith Greiner (1994) that Ehrlich's projections could not possibly have held the scrutiny of time, because Ehrlich applied the financial compound interest formula to population growth. Using two sets of assumptions based on Ehrlich's hypothesis, it was shown that the theorized wild growth in population and subsequent scarcity of resources could not have occurred on Ehrlich's time schedule.

World population

According to estimates published by the United States Census Bureau, the world population at the beginning of December 2005 was about 6,483,600,000. The United Nations Population Fund designated October 12, 1999 as the approximate day on which world population reached six billion. This was about 12 years after world population reached five billion, in 1987.

Countries by population

About 4 billion of the world's nearly 6.5 billion people live in Asia. Seven of the world's ten largest countries by population are in Asia(although Russia is also located in Europe). However, a large population is not the same thing as economic size, and the United States, which has a much smaller population than India or China, has a much larger economy.

External links

- Phishare.org (2005). [http://www.phishare.org Population and Health InfoShare]. Retrieved February 13, 2005.
- [http://www.prb.org Population Reference Bureau] (2005). Retrieved February 13, 2005.
- Populationworld.com (2005). [http://www.populationworld.com/ Population World: Population of World]. Retrieved February 13, 2004.
- United Nations (2004). [http://www.un.org/esa/population/ Population Division], Department of Economic and Social Affairs. Retrieved February 13, 2004.
- United States Census Bureau (2005). [http://www.census.gov/cgi-bin/ipc/idbrank.pl Census Bureau - Countries Ranked by Population]. Retrieved February 13, 2005.
- PopulationData.net (2005). [http://www.populationdata.net PopulationData.net - Informations and maps about populations around the world]. Retrieved March 4, 2005.
- World Population Clock (French) [http://www.worldpopclock.com WorldPopClock.com - World population clock].
- [http://www.census.gov/ipc/www/popclockworld.html World Population Clock (English) - US Census] Category:Ecology Category:Sociology Category:Population zh-min-nan:Jîn-kháu ko:인구 ja:人口 simple:Population th:ประชากร

Human

Humans or human beings define themselves in biological, social, and spiritual terms. Biologically, humans are classified as the species Homo sapiens (Latin for "wise man" or "thinking man"): a bipedal primate of the superfamily Hominoidea, together with the other apes: chimpanzees, gorillas, orangutans, and gibbons. Humans have an erect body carriage that frees their upper limbs for manipulating objects and a highly developed brain capable of abstract reasoning, speech, language, and introspection. Bipedal locomotion appears to have evolved before the development of a large brain. The origins of bipedal locomotion and of its role in the evolution of the human brain are topics of ongoing research. The human mind has several distinct attributes. It is responsible for complex behaviour, especially language. Curiosity and observation have led to a variety of explanations for consciousness and the relation between mind and body. Psychology attempts to study behaviour from a scientific point of view. Religious perspectives emphasise a soul, qi or atman as the essence of being, and are often characterised by the belief in and worship of God, gods, spirits, or other people. Philosophy, especially philosophy of mind, attempts to fathom the depths of each of these perspectives. Art, music and literature are often used in expressing these concepts and feelings. Like all primates, humans are inherently social. They create complex social structures composed of co-operating and competing groups. These range from nations and states down to families. Seeking to understand and manipulate the world around them has led to the development of technology and science. Artifacts, beliefs, myths, rituals, values, and social norms have all helped to form humanity's culture.

Terminology

In general, the word "people" is a collective or plural term for any specific group of individual persons. However, when used to refer to a group of humans possessing a common ethnic, cultural or national unitary characteristic or identity, "people" is a singular count noun, and as such takes an "s" in the plural (examples: "the English-speaking peoples of the world", "the indigenous peoples of Brazil"). ethnic Juvenile males are called boys, adult males men, juvenile females girls, and adult females women. Humans are commonly referred to as persons or people, and collectively as Man (capital M), mankind, humankind, humanity, or the human race. Until the 20th century, "human" was only used adjectivally ("pertaining to mankind"). Nominal use of "human" (plural "humans") is short for "human being", and not considered good style in traditional English grammar. As an adjective, "human" is used neutrally (as in "human race"), but "human" and especially "humane" may also emphasise positive aspects of human nature, and can be synonymous with "benevolent" (versus "inhumane"; cf. humanitarian). A distinction is maintained in philosophy and law between the notions "human being", or "man", and "person". The former refers to the species, while the latter refers to a rational agent (see, for example, John Locke's Essay concerning Human Understanding II 27 and Immanuel Kant's Introduction to the Metaphysic of Morals). The term "person" is thus used of non-human animals, and could be used of a mythical being, an artificial intelligence, or an extraterrestrial. An important question in theology and the philosophy of religion concerns whether God is a person. In Latin, "humanus" is the adjectival form of the noun "homo", translated as "man" (to include males and females). The Old English word "man" could also have this generic meaning, as demonstrated by such compounds as "wifman" ("female person") → "wiman" → "woman". For the etymology of "man" see mannaz.

Biology

Anatomy and physiology

mannaz] Humans exhibit fully bipedal locomotion. This leaves the forelimbs available for manipulating objects using opposable thumbs. Humans vary substantially around the mean height and mean weight. Some of this variation is explained by locality and historical factors. Although body size is largely determined by genes, it is also significantly influenced by diet and exercise. The mean height of a North American adult female is 162 centimetres (5 feet 4 inches) and the mean weight is 62 kilograms (137 pounds). North American adult males are typically larger: 175 centimetres (5 feet 9 inches) and 78 kilograms (172 pounds). Human skin appears to be relatively hairless in comparison to other primates; however, most humans have a larger number of hairs on their body than a chimpanzee. The main difference is that human hairs are shorter, finer, and less coloured then the average chimpanzee's, thus rendering them harder to see. The colour of human hair and skin is determined by the presence of coloured pigments called melanins. Most researchers believe that skin darkening was an adaptation that evolved as a defence against UV solar radiation; melanin is an effective sunblock. The skin colour of contemporary humans can range from very dark brown to very pale pink. It is geographically stratified and in general correlates with the environmental level of UV. Human skin and hair colour is controlled in part by the MC1R gene. For example, the red hair and pale skin of some Europeans is the result of mutations in MC1R. Human skin has a capacity to darken (sun tanning) in response to UV exposure. Variation in the ability to sun tan is also controlled in part by MC1R. sun tanning] Because humans are bipedal, the pelvic region and spinal column tend to become worn, creating locomotion difficulties in old age. The individual need for regular intake of food and drink is prominently reflected in human culture, and has led to the development of food science. Failure to obtain food leads to hunger and eventually starvation, while failure to obtain water leads to dehydration and thirst. Both starvation and dehydration cause death if not alleviated. In modern times, obesity amongst humans has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed countries, and is becoming problematic elsewhere. The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child. Elderly people usually sleep for six to seven hours. It is common, however, in modern societies for people to get less sleep than they need, leading to a state of sleep deprivation. The human body is subject to an ageing process and to illness. Medicine is the science that explores methods of preserving bodily health.

Life cycle

health] The human life cycle is similar to that of other placental mammals. New human life develops from conception. An egg is usually fertilised inside the female by sperm from the male through sexual intercourse, though in vitro fertilisation methods are also used. The fertilised egg is called a zygote. The zygote divides inside the female's uterus to become an embryo which over a period of thirty-eight weeks becomes the fetus. At birth, the fully grown fetus is expelled from the female's body and breathes independently as a baby for the first time. At this point, most modern cultures recognise the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus. Compared with that of other species, human childbirth is relatively complicated. Painful labours lasting twenty-four hours or more are not uncommon, and may result in injury to the child or the death of the mother, although the chances of a successful labour increased significantly during the twentieth century in wealthier countries. Natural childbirth remains an arguably more dangerous ordeal in remote, underdeveloped regions of the world, though the women who live in these regions have argued that their natural childbirth methods are safer and less traumatic for mother and child. Natural childbirth Human children are born after a nine-month gestation period, with typically 3–4 kilograms (6–9 pounds) in weight and 50–60 centimetres (20–24 inches) in height in developed countries. [http://www.childinfo.org/eddb/lbw] Helpless at birth, they continue to grow for some years, typically reaching sexual maturity at twelve to fifteen years of age. Boys continue growing for some time after this, reaching their maximum height around the age of eighteen. These values vary too, depending on genes and environment. The human lifespan can be split into a number of stages: infancy, childhood, adolescence, young adulthood, maturity and old age, though the lengths of these stages, especially the later ones, are not fixed. There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15–20 years (the lowest in Uganda at 14.8 years). Life expectancy at birth is 77.2 years in the U.S. as of 2001. [http://www.cdc.gov/nchs/fastats/lifexpec.htm] The expected life span at birth in Singapore is 84.29 years for a female and 78.96 years for a male, while in Botswana, due largely to AIDS, it is 30.99 years for a male and 30.53 years for a female. One in five Europeans, but one in twenty Africans, is 60 years or older, according to The World Factbook. [http://www.cia.gov/cia/publications/factbook] African.]] The number of centenarians in the world was estimated by the United Nations [http://www.un.org/ageing/note5713.doc.htm] at 210,000 in 2002. The maximum life span for humans is thought to be over 120 years. Worldwide, there are 81 men aged 60 or over for every 100 women, and among the oldest, there are 53 men for every 100 women. The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death may cause unease or fear. People who are near death sometimes have a near-death experience, in which they have visions. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife. Institutions of inheritance or ancestor worship may extend an individual's presence beyond his physical lifespan (see immortality).

Genetics

Humans are a eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. At present estimate, humans have approximately 20,000–25,000 genes and share 95% of their DNA with their closest living evolutionary relatives, the two species of chimpanzees. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12368483] Like other mammals, humans have an XY sex determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes affect men more often than women. For example, genes that control the clotting of blood reside on the X chromosome. Women have a blood-clotting gene on each X chromosome so that one normal blood-clotting gene can compensate for a flaw in the gene on the other X chromosome. But men are hemizygous for the blood-clotting gene, since there is no gene on the Y chromosome to control blood clotting. As a result, men will suffer from haemophilia more often than women.

Race and ethnicity

haemophilia, Black, White (Hispanic), and Asian. Top row males, bottom row females.]] Humans often categorise themselves and others in terms of race or ethnicity. In the United States, racial categories are primarily based on language and ethnicity, although biological qualities, such as skin colour, blood type, facial features, ancestry, and other genetic variances are also key factors. Self identification with an ethnic group is usually based on kinship and descent, as well as presumed advantage. When race and ethnicity lead to variant treatment it is thought to impact social identity, giving rise to the theory of identity politics. Although most humans recognise that variances occur within a species, it is often a point of dispute as to what these differences entail, and if discrimination based on race (racism) is acceptable in the early twenty-first century. Race and intelligence, scientific racism, xenophobia and ethnocentrism are just a few of the many basis' for such practices.

Habitat

The view most widely accepted by the anthropological community is that the human species originated in the African savanna between 100 and 200 thousand years BCE, colonised the rest of the Old World and Oceania by 40,000 years BCE, and finally colonised the Americas by 10,000 years BCE. Homo sapiens displaced groups such as Neanderthals and Homo floresiensis through more successful reproduction and competition for resources, and/or extermination. (See Human evolution, Vagina gentium, and Environment of Evolutionary Adaptedness.) Technology has allowed humans to colonise all of the continents and adapt to all climates. Within the last few decades, humans have been able to explore Antarctica, the ocean depths, and space, although long-term habitation of these environments are not yet possible. Humans, with a population of about six thousand million, are one of the most numerous mammals on Earth. Most humans (61%) live in the Asian region. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 5% in Oceania. (See list of countries by population and list of countries by population density.) list of countries by population density (The arctic is at the centre of the map and the numbers are millennia before present).]] The original human lifestyle is hunting-gathering, which is adapted to the savanna. Other human lifestyles are nomadism (often linked to animal herding) and permanent settlements made possible by the development of agriculture. Humans have a great capacity for altering their habitats by various methods, such as agriculture, irrigation, urban planning, construction, transport, and manufacturing goods. Permanent human settlements are dependent on proximity to water and, depending on the lifestyle, other natural resources such as fertile land for growing crops and grazing livestock, or seasonally by populations of prey. With the advent of large-scale trade and transport infrastructure, immediate proximity to these resources has become unnecessary, and in many places these factors are no longer the driving force behind growth and decline of population. Human habitation within closed ecological systems in hostile environments (Antarctica, outer space) is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with a maximum of thirteen humans in space at any given time, starting with Yuri Gagarin's space flight in 1961. Between 1969 and 1974, up to two humans at a time spent brief intervals on the Moon. As of 2005, no other celestial body has been visited by human beings, although there has been a continuous human presence in space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.

Population

2000 From 1800 to 2000, the human population increased from one to six billion. It is expected to crest at around ten billion during the 21st century. In 2004, around 2.5 billion out of 6.3 billion people lived in urban centres, and this is expected to rise during the 21st century. Problems for humans living in cities include various forms of pollution, crime, and poverty, especially in inner city and suburban slums. Geneticists Lynn Jorde and Henry Harpending of the University of Utah have concluded that the variation in the total stock of human DNA is minute compared to that of other species; and that around 74,000 years ago, human population was reduced to a small number of breeding pairs, possibly as small as 1000, resulting in a very small residual gene pool. Various reasons for this bottleneck have been postulated, the most popular, called the Toba catastrophe theory, being the eruption of a volcano at Lake Toba.

Human evolution

The study of human evolution encompasses many scientific disciplines, but most notably physical anthropology and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominids and hominines, such as the australopithecines. Biologically, humans are defined as hominids of the species Homo sapiens, of which the only extant subspecies is Homo sapiens sapiens (Latin for "very wise man"); Homo sapiens idaltu (roughly translated as "elderly wise man") is the extinct subspecies. Modern humans are usually considered the only surviving species in the genus Homo, although some argue that the two species of chimpanzees should be reclassified from Pan troglodytes (Common Chimpanzee) and Pan paniscus (Bonobo/Pygmy Chimpanzee) to Homo troglodytes and Homo paniscus respectively, given that they share a recent ancestor with man. [http://news.nationalgeographic.com/news/2003/05/0520_030520_chimpanzees.html] Full genome sequencing resulted in these conclusions: "After 6 [million] years of separate evolution, the differences between chimp and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice." [http://news.ft.com/cms/s/43445728-1a44-11da-b279-00000e2511c8.html Chimp and human DNA is 96% identical] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, in 2001 a hominine skull approximately seven million years old, classified as Sahelanthropus tchadensis, was discovered in Chad and seems to indicate an earlier divergence. Two prominent scientific theories of the origins of contemporary humans exist. They concern the relationship between modern humans and other hominids: The single-origin or "out of Africa" hypothesis proposes that modern humans evolved in Africa and later replaced hominids in other parts of the world. The multiregional hypothesis proposes that modern humans evolved at least in part from independent hominid populations. Human evolution is characterised by a number of important physiological trends:
- expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning in juvenile humans. Physical anthropologists argue that a reorganisation of the structure of the brain is more important than cranial expansion itself;
- canine tooth reduction;
- bipedal locomotion;
- descent of the larynx, which makes speech possible. Humans are classified as Homo sapiens sapiens. A camp of physical anthropologists see neanderthalensis as a subspecies and classify the neanderthals as Homo sapiens neanderthalensis. A second camp of physical anthropologists see the neanderthals as a distinct species diverging from the modern human lineage over 500,000 years ago. Under this classification, neaderthals are Homo neanderthalensis. Recent DNA analysis suggests that neanderthalensis were not a subspecies. How these trends are related and what their role is in the evolution of complex social organisation and culture are matters of ongoing debate. larynx]]

Intelligence

Most humans consider their species to be the most intelligent in the animal kingdom. Certainly, humans are the only technologically advanced animal. Along with the brain's internal complexity, the brain to body mass ratio is generally assumed to be a good indicator of relative intelligence. Humans have the second highest ratio, with the tree shrew having the highest [http://www.hindustantimes.com/news/181_935198,00300006.htm], and the bottlenose dolphin very similar to humans. The human ability to abstract may be unparalleled in the animal kingdom. Human beings are one of five species to pass the mirror test — which tests whether an animal recognises its reflection as an image of itself — along with chimpanzees or bonobos, orangutans, and dolphins. Human beings under the age of four usually fail the test.

Culture

dolphin]] Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. Culture consists of at least three elements: values, social norms, and artifacts. A culture's values define what it holds to be important. Norms are expectations of how people ought to behave. Artifacts — things, or material culture — derive from the culture's values and norms together with its understanding of the way the world functions.

Origins

Essentially every culture has its characteristic origin beliefs. Creationism or creation theology is the belief that humans, the Earth, the universe and the multiverse were created by a supreme being or deity. The event itself may be seen either as an act of creation (ex nihilo) or the emergence of order from preexisting chaos (demiurge). Many who hold "creation" beliefs consider such belief to be a part of religious faith, and hence compatible with, or otherwise unaffected by scientific views while others maintain the scientific data is compatible with creationism. Proponents of evolutionary creationism may claim that understood scientific mechanisms are simply aspects of supreme creation. Otherwise, science-oriented believers may consider the scriptural account of creation as simply a metaphor.

Language

metaphor, Chinese, Korean, Hebrew and Greek]] Values, norms and technology are dependent on the capacity for humans to share ideas. The faculty of speech may be a defining feature of humanity, probably predating phylogenetic separation of the modern population. (See Proto-World language, Origins of language.) Language is central to the communication between humans. Some scientists argue that non-human animals are able to use some form of language too, and that non-human primates are able to learn human sign language [http://www.mnsu.edu/emuseum/cultural/language/chimpanzee.html] [http://www.msubillings.edu/asc/PDF-WritingLab/3-Minute%20Spr05/APA%20sample%20paper.pdf] (pdf). Language is central to the sense of identity that unites cultures and ethnicities. The invention of writing systems some 5000 years ago, allowing the preservation of speech, was a major step in cultural evolution. Language, especially written language, is sometimes thought to have supernatural status or powers. (See Magic, Mantra, Vac.) The science of linguistics describes the structure of language and the relationship between languages. There are estimated to be some 6,000 different languages, including sign languages, used today.

Music

Music is a natural intuitive phenomenon operating in the three worlds of time, pitch, and energy, and under the three distinct and interrelated organisation structures of rhythm, harmony, and melody. Composing, improvising and performing music are all art forms. Listening to music is perhaps the most common form of entertainment, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.

Emotion and sexuality

Human emotion has a significant influence on, or can even be said to control, human behaviour. Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate. Human exploration of emotions as separate from other neurological phenomena is worth note, particularly in those cultures were emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy. ecstasy"]] In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilised tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime. Human sexuality, besides ensuring reproduction, has important social functions, creating physical intimacy, bonds and hierarchies among individuals, and that may be directed to spiritual transcendence, and/or to the enjoyment of activity involving sexual gratification. Sexual desire, libido, is experienced as a bodily urge, often accompanied by strong emotions, both positive (such as love or ecstasy) and negative (such as jealousy). As with other human self-descriptions, humans propose it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal. Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are largely determined by religious beliefs.

Body image

norms, Japan]]The physical appearance of the human body is central to culture and art. In every human culture, people adorn their bodies with tattoos, cosmetics, clothing, and jewellery. Hairstyles and hair colour also have important cultural implications. The perception of an individual as physically beautiful or ugly can have profound implications for their lives. This is particularly true of women, whose external appearance is highly valued in most, if not all, human societies. Anthropologists believe this to be an important factor in the development of personality and social relations in particular physical attractiveness. There is a relatively low sexual dimorphism between human males and females in comparison with other mammals.

Trade and economics

sexual dimorphism.]] Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade exists for many reasons. Due to specialisation and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations. Economics is a social science that studies the production, distribution, trade and consumption of goods and services. Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.

Artifacts, technology, and science

supply and demand.]] Human cultures are both characterised and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewellery that are particular to various regions and times. Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated. Such techniques can be passed on by oral tradition. The development of writing, itself a type of artifact, made it possible to pass information from generation to generation and from region to region with greater accuracy. Together, these developments made possible the commencement of civilisation and urbanisation, with their inherently complex social arrangements. Eventually this led to the institutionalisation of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture. In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic explosion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (10⁹) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.

Mind

physical laws Consciousness is a state of mind, said to possess qualities such as, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The way in which the world is experienced is the subject of much debate and research in philosophy of mind, psychology, brain biology, neurology, and cognitive science. Humans (and often others as well) are variously said to possess consciousness, self-awareness, and a mind, the fruition of being our senses and perceptions. Each of us has a subjective view of existence, the passage of time, and free will. There are many debates about the extent to which the mind constructs or experiences the outer world, and regarding the definitions and validity of many of the terms used above. Cognitive scientist Daniel Dennett, for example, argues that there is no such thing as a narrative centre called mind, but that instead there is simply a collection of sensory inputs and outputs: different kinds of software running in parallel (Dennett, 1991).

Psychology and human ethology

Psychology (Classical Greek: psyche = "soul" or "mind", logos = "study of") is the study of behaviour, mind and thought and the neurological basis for them. Psychoanalysis, the examination of the subconscious was, devised by Sigmund Freud and expanded and refined by the Swiss psychiatrist Carl Gustav Jung (initially one of Freud's followers and friends) and others. Carl Gustav Jung Freud divided the mind into the id (an individual's basic needs and instincts), the superego (personal and cultural values and norms), and the ego (the central, organising self, whose job it is to satisfy the id but not upset the superego). [http://allpsych.com/psychology101/ego.html] C. G. Jung founded the school of analytical psychology and introduced the notion of the collective unconscious, a term taken from philosophy and used by Jung to describe symbols or archetypes that he believed might be common to all cultures. There are also the Conscious, Subconscious, and Superconsciousness, a related but not identical set of categories. The behaviour and mental processes of animals (human and non-human) can be described through animal cognition, ethology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with their environment, nature and the human social environment.

Philosophy

social environment in detail from Raphael's School of Athens]] Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of values and reality by chiefly speculative rather than observational means comprising as its core logic, ontology or metaphysics, epistemology, and axiology which includes the branches of ethics and aesthetics. The term covers a very wide range of approaches, and is also used to refer to a worldview, to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy. Metaphysics is a branch of philosophy concerned with the study of "first principles" and "being" (ontology). Problems that were not originally considered metaphysical have been added to metaphysics. Other problems that were considered metaphysical problems for centuries are now typically relegated to their own separate subheadings in philosophy, such as philosophy of religion, philosophy of mind, philosophy of perception, philosophy of language, and philosophy of science. In rare cases subjects of metaphysical research have been found to be entirely physical and natural. The mind is the term most commonly used to describe the higher functions of the human brain, particularly those of which humans are subjectively conscious, such as personality, thought, reason, memory, intelligence and emotion. Other species of animals share some of these mental capacities, and it is also used in relation to supernatural beings, as in the expression "the mind of God." The term is used here only in relation to humans. There are many Philosophies of mind, the most common relating to the nature of being, and ones way of being, or purpose. Adi Shankara in the East proposed Advaita Vedanta, a popular argument for monism (the metaphysical view that all is of one essential essence, substance or energy). Another type of monism is physicalism or statistical practice concerned with the selection of individual observations intended to yield some knowledge about a population of concern, especially for the purposes of statistical inference. In particular, results from probability theory and statistical theory are employed to guide practice. The sampling process consists of five stages:(Makerere University Institute of Statistics & Applied Economics (ISAE)
- Definition of population of concern
- Specification of a sampling frame, a set of items or events that it is possible to measure
- Specification of sampling method for selecting items or events from the frame
- Sampling and data collecting
- Review of sampling process

Population definition

Successful statistical practice is based on focused problem definition. Typically, we seek to take action on some population, for example when a batch of material from production must be released to the customer or sentenced for scrap or rework. Alternatively, we seek knowledge about the cause system of which the population is an outcome, for example when a researcher performs an experiment on rats with the intention of gaining insights into biochemistry that can be applied for the benefit of humans. In the latter case, the population of concern can be difficult to specify, as it is in the case of measuring some physical characteristic such as the electrical conductivity of copper. However, in all cases, time spent in making the population of concern precise is often well spent, often because it raises many issues, ambiguities and questions that would otherwise have been overlooked at this stage.

Sampling frame

In the most straightforward case, such as the sentencing of a batch of material from production (acceptance sampling by lots), it is possible to identify and measure every single item in the population and to include any one of them in our sample. However, in the more general case this is not possible. There is no way to identify all rats in the set of all rats. There is no way to identify every voter at a forthcoming election (in advance of the election). These imprecise populations are not amenable to sampling in any of the ways below and to which we could apply statistical theory. As a remedy, we seek a sampling frame which has the property that we can identify every single element and include any in our sample. For example, in an electoral poll, possible sampling frames include:
- Electoral register
- Telephone directory
- Shoppers in Anytown, High Street on the Monday afternoon before the election. The sampling frame must be representative of the population and this is a question outside the scope of statistical theory demanding the judgement of experts in the particular subject matter being studied. All the above frames omit some people who will vote at the next election and contain some people who will not. People not in the frame have no prospect of being sampled. Statistical theory tells us about the uncertainties in extrapolating from a sample to the frame. In extrapolating from frame to population its role is motivational and suggestive. In defining the frame, practical, economic, ethical and technical issues need to be addressed. The need to obtain timely results may prevent extending the frame far into the future. The difficulties can be extreme when the population and frame are disjoint. This is a particular problem in forecasting where inferences about the future are made from historical data. In fact, in 1703, when Jacob Bernoulli proposed to Gottfried Leibniz the possibility of using historical mortality data to predict the probability of early death of a living man, Gottfried Leibniz recognised the problem in replying: Nature has established patterns originating in the return of events but only for the most part. New illnesses flood the human race, so that no matter how many experiments you have done on corpses, you have not thereby imposed a limit on the nature of events so that in the future they could not vary. Having established the frame, there are a number of ways of organising it to improve efficiency and effectiveness.

Simple sampling

In this case, all elements of the frame are treated equally and it is not subdivided or partitioned. One of the sampling methods below is applied to the whole frame.l

Stratified sampling

Where the population embraces a number of distinct categories, the frame can be organised by these categories into separate strata or demographics. One of the sampling methods below is then applied to each stratum separately. Major gains in efficiency (either lower sample sizes or higher precision) can be achieved by varying the sampling fraction from stratum to stratum. The sample size should be made proportional to the stratum standard deviation. From the efficiency point of view (i.e. maximum precision for a given sample size) strata should be chosen to have
- means which differ substantially from one another
- variances which are different from one another, and lower than the overall variance

Cluster sampling

Where items in the population are clustered, sampling can reflect this to minimise costs or for ease of data collection. For example, a simple random sample of telephone calls is difficult to obtain from a telephone exchange, but it is easy to take a sample of customer lines and observe all the call on the sampled lines. That is, calls are naturally clustered by lines. Sample units within clusters tend to be more similar than randomly chosen sample units and thus clustering requires larger sample sizes to compensate for this.

Sampling method

Within any of the types of frame identified above, a variety of sampling methods can be employed, individually or in combination.

Random sampling

In random sampling, also known as probability sampling, every combination of items from the frame, or stratum, has a known probability of occurring, but these probabilities are not necessarily equal. With any form of sampling there is a risk that the sample may not adequately represent the population but with random sampling there is a large body of statistical theory which quantifies the risk and thus enables an appropriate sample size to be chosen. Furthermore, once the sample has been taken the sampling error associated with the measured results can be computed. With non-random sampling there is no measure of the associated sampling error. While such methods may be cheaper this is largely meaningless since there is no measure of quality. There are several forms of random sampling. For example, in simple random sampling, each element has an equal probability of occurring. It may be infeasible in many practical situations. Other examples of probability sampling include stratified sampling and multistage sampling.

Systematic sampling

Selecting (say) every tenth name from the telephone directory is simple to implement and is an example of systematic sampling. Though simple to implement, asymmetries and biases in the structure of the data can lead to bias in results. It is a type of nonprobability sampling unless the directory itself is randomized.

Mechanical sampling

Mechanical sampling occurs typically in sampling solids, liquids and gases, using devices such as grabs, scoops, thief probes, the coliwasa and riffle splitter. Mechanical sampling is not random and is a type of nonprobability sampling. Care is needed in ensuring that the sample is representative of the frame. Much work in this area was developed by Pierre Gy.

Convenience sampling

Sometimes called, grab or opportunity sampling, this is the method of choosing items arbitrarily and in an unstructured manner from the frame. Though almost impossible to treat rigorously, it is the method most commonly employed in many practical situations. In social science research, snowball sampling is a similar technique, where existing study subjects are used to recruit more subjects into the sample.

Sample size

Where the frame and population are identical, statistical theory yields exact recommendations on sample size. However, where it is not straightforward to define a frame representative of the population, it is more important to understand the cause system of which the population are outcomes and to ensure that all sources of variation are embraced in the frame. Large number of observations are of no value if major sources of variation are neglected in the study. In other words, it is taking a sample group that matches the survey category and is easy to survey.l

Sampling and data collection

Good data collection involves:
- Following the defined sampling process
- Keeping the data in time order
- Noting comments and other contextual events
- Recording non-responses

Review of sampling process

After sampling, a review should be held of the exact process followed in sampling, rather than that intended, in order to study any effects that any divergences might have on subsequent analysis. A particular problem is that of non-responses.

Non-responses

In survey sampling, many of the individuals identified as part of the sample may be unwilling to participate or impossible to contact. In this case, there is a risk of differences, between (say) the willing and unwilling, leading to selection bias in conclusions. This is often addressed by follow-up studies which make a repeated attempt to contact the unresponsive and to characterise their similarities and differences with the rest of the frame.

Weighting of samples

In many situations the sample fraction may be varied by stratum and data will have to be weighted to correctly represent the population. Thus for example, a simple random sample of individuals in the United Kingdom might include some in remote Scottish islands who would be inordinately expensive to sample. A cheaper method would be to use a stratified sample with urban and rural strata. The rural sample could be under-represented in the sample, but weighted up appropriately in the analysis to compensate.

History of sampling

The idea of random sampling by the use of lots is an old one, mentioned several times in the Bible. In 1786 Pierre Simon Laplace estimated the population of France by using a sample, along with ratio estimator. He also computed probabilistic estimates of the error. These were not expressed as modern confidence intervals but as the sample size that would be needed to achieve a particular upper bound on the sampling error with probability 1000/1001. His estimates used Bayes' theorem with a uniform prior and it assumed his sample was random.The theory of small-sample statistics developed by Gossett put the subject on a more rigorous basis in the 20th century. However, the importance of random sampling was not universally appreciated and in the USA the 1936 Literary Digest prediction of a Republican win in the presidential election went badly awry, due to severe bias. A sample size of one million was obtained through magazine subscription lists and telephone directories. It was not appreciated that these lists were heavily biased towards Republicans and the resulting sample, though very large, was deeply flawed.

Graduate Degree Programs specializing in Sampling/Survey Methods

Doctoral and Masters Degrees

- [http://www.socsci.soton.ac.uk/socstats/Study_Opportunities/Postgradua