Census
"[3] The word is of Latin origin: during the Roman Republic, the census was a list of all adult males fit for military service.
Censuses typically began as the only method of collecting national demographic data and are now part of a larger system of different surveys.
Current administrative data systems allow for other approaches to enumeration with the same level of detail but raise concerns about privacy and the possibility of biasing estimates.
Similarly, stratification requires knowledge of the relative sizes of different population strata, which can be derived from census enumerations.
In some countries, the census provides the official counts used to apportion the number of elected representatives to regions (sometimes controversially – e.g., Utah v. Evans).
A particular problem is what is termed "communal establishments", a category that includes student residences, religious orders, homes for the elderly, people in prisons, etc.
As these are not easily enumerated by a single householder, they are often treated differently and visited by special teams of census workers to ensure they are classified appropriately.
People with second homes, because they are working in another part of the country or have a holiday cottage, are difficult to fix at a particular address; this sometimes causes double counting or houses being mistakenly identified as vacant.
It is also possible that the hidden nature[clarification needed] of an administrative census means that users are not engaged with the importance of contributing their data to official statistics.
The UNFPA said:[24] "The unique advantage of the census is that it represents the entire statistical universe, down to the smallest geographical units, of a country or region.
"In addition to making policymakers aware of population issues, the census is also an important tool for identifying forms of social, demographic or economic exclusions, such as inequalities relating to race, ethics, and religion as well as disadvantaged groups such as those with disabilities and the poor.
In some countries, census archives are released for public examination after many decades, allowing genealogists to track the ancestry of interested people.
[29] This is particularly important when individuals' census responses are made available in microdata form, but even aggregate-level data can result in privacy breaches when dealing with small areas and/or rare subpopulations.
Some agencies do this by intentionally introducing small statistical errors to prevent the identification of individuals in marginal populations;[30] others swap variables for similar respondents.
Whatever is done to reduce the privacy risk, new improved electronic analysis of data can threaten to reveal sensitive individual information.
[31] The statistical information in the form of conditional distributions (histograms) can be derived interactively from the estimated mixture model without any further access to the original database.
[40] One of the world's earliest preserved censuses[41] was held in China in AD 2 during the Han dynasty, and is still considered by scholars to be quite accurate.
[42][43][44][45] The population was registered as having 57,671,400 individuals in 12,366,470 households but on this occasion only taxable families had been taken into account, indicating the income and the number of soldiers who could be mobilized.
The oldest recorded census in India is thought to have occurred around 330 BC during the reign of Emperor Chandragupta Maurya under the leadership of Chanakya and Ashoka.
The census played a crucial role in the administration of the Roman government, as it was used to determine the class a citizen belonged to for both military and tax purposes.
It is said to have been instituted by the Roman king Servius Tullius in the 6th century BC,[49] at which time the number of arms-bearing citizens was supposedly counted at around 80,000.
[50] When the Romans conquered Judea in AD 6, the legate Publius Sulpicius Quirinius organized a census for tax purposes, which was partially responsible for the development of the Zealot movement and several failed rebellions against Rome ultimately ending in the Jewish Diaspora.
The Gospel of Luke makes reference to Quirinius' census in relation to the birth of Jesus;[51] based on variant readings of this passage, a minority of biblical scholars, including N. T. Wright, speculate that this passage refers to a separate registration conducted during the reign of Herod the Great, several years before Quirinius' census.
[52] The 15-year indiction cycle established by Diocletian in AD 297 was based on quindecennial censuses and formed the basis for dating in late antiquity and under the Byzantine Empire.
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.
Instructions and a questionnaire, issued in 1577 by the Office of the Cronista Mayor, were distributed to local officials in the Viceroyalties of New Spain and Peru to direct the gathering of information.
The earliest estimate of the world population was made by Giovanni Battista Riccioli in 1661; the next by Johann Peter Süssmilch in 1741, revised in 1762; the third by Karl Friedrich Wilhelm Dieterici in 1859.
[55] In 1931, Walter Willcox published a table in his book, International Migrations: Volume II Interpretations, that estimated the 1929 world population to be roughly 1.8 billion.
Thus, a delay in any census activity may be critical and can result in a full year postponement of the enumeration if the agricultural season is missed.
While new census methods, including online, register-based, and hybrid approaches are being used across the world, these demand extensive planning and preconditions that cannot be created at short notice.
