Census
A census is the procedure of systematically acquiring, recording and calculating population information about the members of a given population. This term is used mostly in connection with national population and housing censuses; other common censuses include censuses of agriculture, traditional culture, business, supplies, and traffic censuses. The United Nations (UN) defines the essential features of population and housing censuses as "individual enumeration, universality within a defined territory, simultaneity and defined periodicity", and recommends that population censuses be taken at least every ten years. UN recommendations also cover census topics to be collected, official definitions, classifications and other useful information to co-ordinate international practices.[1][2]
The UN's Food and Agriculture Organization (FAO), in turn, defines the census of agriculture as "a statistical operation for collecting, processing and disseminating data on the structure of agriculture, covering the whole or a significant part of a country." "In a census of agriculture, data are collected at the holding level."[3]
The word is of Latin origin: during the Roman Republic, the census was a list of all adult males fit for military service. The modern census is essential to international comparisons of any type of statistics, and censuses collect data on many attributes of a population, not just the number of individuals. Censuses typically began as the only method of collecting national demographic data and are now part of a larger system of different surveys. Although population estimates remain an important function of a census, including exactly the geographic distribution of the population or the agricultural population, statistics can be produced about combinations of attributes, e.g., education by age and sex in different regions. 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.[4]
A census can be contrasted with sampling in which information is obtained only from a subset of a population; typically, main population estimates are updated by such intercensal estimates. Modern census data are commonly used for research, business marketing, and planning, and as a baseline for designing sample surveys by providing a sampling frame such as an address register. Census counts are necessary to adjust samples to be representative of a population by weighting them as is common in opinion polling. 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). In many cases, a carefully chosen random sample can provide more accurate information than attempts to get a population census.[5]
Residence definitions[edit]
Individuals are normally counted within households, and information is typically collected about the household structure and the housing. For this reason, international documents refer to censuses of population and housing. Normally the census response is made by a household, indicating details of individuals resident there. An important aspect of census enumerations is determining which individuals can be counted and which cannot be counted. Broadly, three definitions can be used: de facto residence; de jure residence; and permanent residence. This is important in considering individuals who have multiple or temporary addresses. Every person should be identified uniquely as resident in one place; but the place where they happen to be on Census Day, their de facto residence, may not be the best place to count them. Where an individual uses services may be more useful, and this is at their usual residence. An individual may be recorded at a "permanent" address, which might be a family home for students or long-term migrants.[8]
A precise definition of residence is needed, to decide whether visitors to a country should be included in the population count. This is becoming more important as students travel abroad for education for a period of several years. Other groups causing problems of enumeration are new-born babies, refugees, people away on holiday, people moving home around census day, and people without a fixed address.
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. Another problem is where people use a different address at different times e.g. students living at their place of education in term time but returning to a family home during vacations, or children whose parents have separated who effectively have two family homes. Census enumeration has always been based on finding people where they live, as there is no systematic alternative: any list used to find people is likely to be derived from census activities in the first place. Recent UN guidelines provide recommendations on enumerating such complex households.[9]
In the census of agriculture, data is collected at the agricultural holding unit. An agricultural holding is an economic unit of agricultural production under single management comprising all livestock kept and all land used wholly or partly for agricultural production purposes, without regard to title, legal form, or size. Single management may be exercised by an individual or household, jointly by two or more individuals or households, by a clan or tribe, or by a juridical person such as a corporation, cooperative or government agency. The holding's land may consist of one or more parcels, located in one or more separate areas or in one or more territorial or administrative divisions, providing the parcels share the same production means, such as labour, farm buildings, machinery or draught animals.[3]
Technology[edit]
Censuses have evolved in their use of technology: censuses in 2010 used many new types of computing. In Brazil, handheld devices were used by enumerators to locate residences on the ground. In many countries, census returns could be made via the Internet as well as in paper form. DSE is facilitated by computer matching techniques that can be automated, such as propensity score matching. In the UK, all census formats are scanned and stored electronically before being destroyed, replacing the need for physical archives. The record linking to perform an administrative census would not be possible without large databases being stored on computer systems.
There are sometimes problems in introducing new technology. The US census had been intended to use handheld computers, but cost escalated, and this was abandoned, with the contract being sold to Brazil. Online response has some advantages, but one of the functions of the census is to make sure everyone is counted accurately. A system that allowed people to enter their address without verification would be open to abuse. Therefore, households have to be verified on the ground, typically by an enumerator visit or post out. Paper forms are still necessary for those without access to the internet. It is also possible that the hidden nature of an administrative census means that users are not engaged with the importance of contributing their data to official statistics.
Alternatively, population estimations may be carried out remotely with geographic information system (GIS) and remote sensing technologies.[22]
Privacy and data stewardship[edit]
Although the census provides useful statistical information about a population, the availability of this information could sometimes lead to abuses, political or otherwise, by the linking of individuals' identities to anonymous census data.[28] 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.
For instance, when reporting data from a large city, it might be appropriate to give the average income for black males aged between 50 and 60. However, doing this for a town that only has two black males in this age group would be a breach of privacy because either of those persons, knowing his own income and the reported average, could determine the other man's income.
Typically, census data are processed to obscure such individual information. Some agencies do this by intentionally introducing small statistical errors to prevent the identification of individuals in marginal populations;[29] 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. This is known as statistical disclosure control.
Another possibility is to present survey results by means of statistical models in the form of a multivariate distribution mixture.[30] 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. As the final product does not contain any protected microdata, the model-based interactive software can be distributed without any confidentiality concerns.
Another method is simply to release no data at all, except very large scale data directly to the central government. Differing release strategies of governments have led to an international project (IPUMS) to co-ordinate access to microdata and corresponding metadata. Such projects such as SDMX also promote standardising metadata, so that best use can be made of the minimal data available.
History of censuses[edit]
Egypt[edit]
Censuses in Egypt first appeared in the late Middle Kingdom and developed in the New Kingdom[31] Pharaoh Amasis, according to Herodotus, required every Egyptian to declare annually to the nomarch, "whence he gained his living".[32] Under the Ptolemies and the Romans several censuses were conducted in Egypt by government officials [33]
Israel[edit]
Censuses are mentioned in the Bible. God commands a per capita tax to be paid with the census[35] for the upkeep of the Tabernacle. The Book of Numbers is named after the counting of the Israelite population[36] according to the house of the Fathers after the exodus from Egypt. A second census was taken while the Israelites were camped in the "plains of Moab".[37]
King David performed a census that produced disastrous results.[38] His son, King Solomon, had all of the foreigners in Israel counted.[39]
When the Romans took over Judea in AD 6, the legate Publius Sulpicius Quirinius organised a census for tax purposes. The Gospel of Luke links the birth of Jesus either to this event, or to an otherwise unknown census conducted prior to Quirinius' tenure.[40][41]
China[edit]
One of the world's earliest preserved censuses[42] was held in China in AD 2 during the Han dynasty, and is still considered by scholars to be quite accurate.[43][44][45][46] 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.[47][45] Another census was held in AD 144.
India[edit]
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.[48]
Impact of COVID-19 on census[edit]
Impact[edit]
The UNFPA predicts that the COVID-19 pandemic will threaten the successful conduct of censuses of population and housing in many countries through delays, interruptions that compromise quality, or complete cancellation of census projects. Domestic and donor financing for census may be diverted to address COVID-19 leaving census without crucial funds. Several countries have already taken decisions to postpone the census, with many others yet to announce the way forward. In some countries this is already happening.[55]
The pandemic has also affected the planning and implementation of censuses of agriculture in all world regions. The extent of the impact has varied according to the stages at which the censuses are, ranging from planning (i.e. staffing, procurement, preparation of frames, questionnaires), fieldwork (field training and enumeration) or data processing/analysis stages. The census of agriculture's reference period is the agricultural year. 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. Some publications have discussed the impact of COVID-19 on national censuses of agriculture.[56][57][58][59]
Adaptation[edit]
The United Nations Population Fund (UNFPA) has requested a global effort to assure that even where census is delayed, census planning and preparations are not cancelled, but continue in order to assure that implementation can proceed safely when the pandemic is under control. 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. The continuing low supply of personal protective equipment to protect against COVID-19 has immediate implications for conducting census in communities at risk of transmission. The UNFPA Procurement Office is partnering with other agencies to explore new supply chains and resources.[55]
Sources[edit]
This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 IGO (license statement/permission). Text taken from World Programme for the Census of Agriculture 2020 Volume 1 – Programme, concepts and definitions, FAO, FAO.
This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 IGO (license statement/permission). Text taken from National agricultural census operations and COVID-19, FAO, FAO.
This article incorporates text from a free content work. Licensed under CC BY-SA 3.0 IGO (license statement/permission). Text taken from Impact of COVID-19 on national censuses of agriculture (Status overview) (2020), FAO, FAO.