Albuñol is a town in the province of Granada , Spain. Located a few miles inland, it is regarded as one of the gateways to the Alpujarras mountains . The municipality includes the small beach resort of La Rabita.
115-559: According to the 2007 census , Albuñol had a population of 6,270 inhabitants. Remains have been found of a prehistoric settlement in the Cave of Bats, located in the municipality, but Albuñol itself is believed to be of Roman origin. The heyday of the Alpujarra was the Moors, at the time Albuñol contained the largest population of Great Cehel or Gran Costa. It was in these centuries Albuñol was defended by
230-638: A base-10 positional system. On May 25, 1577, King Philip II of Spain ordered by royal cédula the preparation of a general description of Spain's holdings in the Indies. 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 questionnaire, composed of fifty items,
345-533: 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 ; based on variant readings of this passage, a minority of biblical scholars, including N. T. Wright , speculate that this passage refers to
460-608: A statistical population to estimate characteristics of the whole population. The subset is meant to reflect the whole population and statisticians attempt to collect samples that are representative of the population. Sampling has lower costs and faster data collection compared to recording data from the entire population, and thus, it can provide insights in cases where it is infeasible to measure an entire population. Each observation measures one or more properties (such as weight, location, colour or mass) of independent objects or individuals. In survey sampling , weights can be applied to
575-406: A better understanding of human health, or one might study records from people born in 2008 in order to make predictions about people born in 2009. Time spent in making the sampled population and population of concern precise is often well spent because it raises many issues, ambiguities, and questions that would otherwise have been overlooked at this stage. In the most straightforward case, such as
690-402: A census is that the population is not known, and a new estimate is to be made by the analysis of primary data. The use of a sampling frame is counterintuitive as it suggests that the population size is already known. However, a census is also used to collect attribute data on the individuals in the nation, not only to assess population size. This process of sampling marks the difference between
805-477: 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 one or more territorial or administrative divisions, providing the parcels share the same production means, such as labor, farm buildings, machinery or draught animals. Historical censuses used crude enumeration assuming absolute accuracy. Modern approaches take into account
920-403: 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 with enumeration are newborn 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
1035-499: A fishing analogy can be found in "Trout, Catfish and Roach..." which won an award from the Royal Statistical Society for excellence in official statistics in 2011. Triple system enumeration has been proposed as an improvement as it would allow evaluation of the statistical dependence of pairs of sources. However, as the matching process is the most difficult aspect of census estimation this has never been implemented for
1150-415: 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. The most straightforward type of frame is a list of elements of the population (preferably
1265-506: A given country will on average produce five men and five women, but any given trial is likely to over represent one sex and underrepresent the other. Systematic and stratified techniques attempt to overcome this problem by "using information about the population" to choose a more "representative" sample. Also, simple random sampling can be cumbersome and tedious when sampling from a large target population. In some cases, investigators are interested in research questions specific to subgroups of
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#17330854508681380-413: A given size, all subsets of a sampling frame have an equal probability of being selected. Each element of the frame thus has an equal probability of selection: the frame is not subdivided or partitioned. Furthermore, any given pair of elements has the same chance of selection as any other such pair (and similarly for triples, and so on). This minimizes bias and simplifies analysis of results. In particular,
1495-606: A given street, and interview the first person to answer the door. In any household with more than one occupant, this is a nonprobability sample, because some people are more likely to answer the door (e.g. an unemployed person who spends most of their time at home is more likely to answer than an employed housemate who might be at work when the interviewer calls) and it's not practical to calculate these probabilities. Nonprobability sampling methods include convenience sampling , quota sampling , and purposive sampling . In addition, nonresponse effects may turn any probability design into
1610-428: A historical census, which was a house-to-house process or the product of an imperial decree, and the modern statistical project. The sampling frame used by a census is almost always an address register. Thus, it is not known if there are any residents or how many people there are in each household. Depending on the mode of enumeration, a form is sent to the householder, an enumerator calls, or administrative records for
1725-500: 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
1840-469: A national enumeration. It would also be difficult to identify three different sources that were sufficiently different to make the triple system effort worthwhile. The DSE approach has another weakness in that it assumes there is no person counted twice (over count). In de facto residence definitions this would not be a problem but in de jure definitions individuals risk being recorded on more than one form leading to double counting. A particular problem here
1955-410: A nonprobability design if the characteristics of nonresponse are not well understood, since nonresponse effectively modifies each element's probability of being sampled. Within any of the types of frames identified above, a variety of sampling methods can be employed individually or in combination. Factors commonly influencing the choice between these designs include: In a simple random sample (SRS) of
2070-433: A population and housing census – numbers of people, their distribution, their living conditions and other key data – is critical for development." This is because this type of data is essential for policymakers so that they know where to invest. Many countries have outdated or inaccurate data about their populations and thus have difficulty in addressing the needs of the population. The UNFPA said: "The unique advantage of
2185-423: A population census. A census is often construed as the opposite of a sample as it intends to count everyone in a population, rather than a fraction. However, population censuses do rely on a sampling frame to count the population. This is the only way to be sure that everyone has been included, as otherwise those not responding would not be followed up on and individuals could be missed. The fundamental premise of
2300-549: A population is obvious. For example, a manufacturer needs to decide whether a batch of material from production is of high enough quality to be released to the customer or should be scrapped or reworked due to poor quality. In this case, the batch is the population. Although the population of interest often consists of physical objects, sometimes it is necessary to sample over time, space, or some combination of these dimensions. For instance, an investigation of supermarket staffing could examine checkout line length at various times, or
2415-451: A population than for the overall population; in such cases, using a stratified sampling approach may be more convenient than aggregating data across groups (though this may potentially be at odds with the previously noted importance of utilizing criterion-relevant strata). Finally, since each stratum is treated as an independent population, different sampling approaches can be applied to different strata, potentially enabling researchers to use
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#17330854508682530-536: A probability proportionate to size sample. This is done by treating each count within the size variable as a single sampling unit. Samples are then identified by selecting at even intervals among these counts within the size variable. This method is sometimes called PPS-sequential or monetary unit sampling in the case of audits or forensic sampling. Example: Suppose we have six schools with populations of 150, 180, 200, 220, 260, and 490 students respectively (total 1500 students), and we want to use student population as
2645-616: A probability sample is the fact that each person's probability is known. When every element in the population does have the same probability of selection, this is known as an 'equal probability of selection' (EPS) design. Such designs are also referred to as 'self-weighting' because all sampled units are given the same weight. Probability sampling includes: simple random sampling , systematic sampling , stratified sampling , probability-proportional-to-size sampling, and cluster or multistage sampling . These various ways of probability sampling have two things in common: Nonprobability sampling
2760-460: A realist approach to measurement, acknowledging that under any definition of residence there is a true value of the population but this can never be measured with complete accuracy. An important aspect of the census process is to evaluate the quality of the data. Many countries use a post-enumeration survey to adjust the raw census counts. This works similarly to capture-recapture estimation for animal populations. Among census experts, this method
2875-439: A 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. A precise definition of residence is needed, to decide whether visitors to
2990-678: A separate registration conducted during the reign of Herod the Great , several years before Quirinius' census. 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 the Middle Ages , the Caliphate began conducting regular censuses soon after its formation, beginning with
3105-404: A single trip to visit several households in one block, rather than having to drive to a different block for each household. It also means that one does not need a sampling frame listing all elements in the target population. Instead, clusters can be chosen from a cluster-level frame, with an element-level frame created only for the selected clusters. In the example above, the sample only requires
3220-461: A study on endangered penguins might aim to understand their usage of various hunting grounds over time. For the time dimension, the focus may be on periods or discrete occasions. In other cases, the examined 'population' may be even less tangible. For example, Joseph Jagger studied the behaviour of roulette wheels at a casino in Monte Carlo , and used this to identify a biased wheel. In this case,
3335-499: A uniform prior probability and assumed that his sample was random. Alexander Ivanovich Chuprov introduced sample surveys to Imperial Russia in the 1870s. In the US, the 1936 Literary Digest prediction of a Republican win in the presidential election went badly awry, due to severe bias [1] . More than two million people responded to the study with their names obtained through magazine subscription lists and telephone directories. It
3450-477: A using a skip which ensures jumping between the two sides (any odd-numbered skip). Another drawback of systematic sampling is that even in scenarios where it is more accurate than SRS, its theoretical properties make it difficult to quantify that accuracy. (In the two examples of systematic sampling that are given above, much of the potential sampling error is due to variation between neighbouring houses – but because this method never selects two neighbouring houses,
3565-467: Is "everybody in the country, given access to this treatment" – a group that does not yet exist since the program is not yet available to all. The population from which the sample is drawn may not be the same as the population from which information is desired. Often there is a large but not complete overlap between these two groups due to frame issues etc. (see below). Sometimes they may be entirely separate – for instance, one might study rats in order to get
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3680-501: Is an old idea, 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
3795-410: Is any sampling method where some elements of the population have no chance of selection (these are sometimes referred to as 'out of coverage'/'undercovered'), or where the probability of selection cannot be accurately determined. It involves the selection of elements based on assumptions regarding the population of interest, which forms the criteria for selection. Hence, because the selection of elements
3910-461: Is based on focused problem definition. In sampling, this includes defining the " population " from which our sample is drawn. A population can be defined as including all people or items with the characteristics one wishes to understand. Because there is very rarely enough time or money to gather information from everyone or everything in a population, the goal becomes finding a representative sample (or subset) of that population. Sometimes what defines
4025-453: Is called dual system enumeration (DSE). A sample of households is visited by interviewers who record the details of the household as of census day. These data are then matched to census records, and the number of people missed can be estimated by considering the number of people who are included in one count but not the other. This allows adjustments to the count for non-response, varying between different demographic groups. An explanation using
4140-467: 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
4255-407: Is eliminated.) However, systematic sampling is especially vulnerable to periodicities in the list. If periodicity is present and the period is a multiple or factor of the interval used, the sample is especially likely to be un representative of the overall population, making the scheme less accurate than simple random sampling. For example, consider a street where the odd-numbered houses are all on
4370-402: 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
4485-435: Is held every June 23; Fiestas Patronal of Nuestra Señora La Virgen del Mar every September 8. In El Pozuelo, fiestas in honor of Santiago Apostle on 25 June. In 1986 was held in this population, the V Festival of Traditional Music of the Alpujarra. This article about a location in the province of Granada is a stub . You can help Misplaced Pages by expanding it . Census A census (from Latin censere , 'to assess')
4600-469: Is interested; researchers in particular have an interest in the role of Census Field Officers (CFO) and their assistants. Data can be represented visually or analysed in complex statistical models, to show the difference between certain areas, or to understand the association between different personal characteristics. Census data offer a unique insight into small areas and small demographic groups which sample data would be unable to capture with precision. In
4715-690: Is named after the counting of the Israelite population 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 ". King David performed a census that produced disastrous results. His son, King Solomon , had all of the foreigners in Israel counted. One of the world's earliest preserved censuses was held in China in AD 2 during
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4830-662: 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. 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
4945-404: Is nonrandom, nonprobability sampling does not allow the estimation of sampling errors. These conditions give rise to exclusion bias , placing limits on how much information a sample can provide about the population. Information about the relationship between sample and population is limited, making it difficult to extrapolate from the sample to the population. Example: We visit every household in
5060-428: 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
5175-424: Is often available – for instance, a survey attempting to measure the number of guest-nights spent in hotels might use each hotel's number of rooms as an auxiliary variable. In some cases, an older measurement of the variable of interest can be used as an auxiliary variable when attempting to produce more current estimates. Sometimes it is more cost-effective to select respondents in groups ('clusters'). Sampling
5290-434: Is often clustered by geography, or by time periods. (Nearly all samples are in some sense 'clustered' in time – although this is rarely taken into account in the analysis.) For instance, if surveying households within a city, we might choose to select 100 city blocks and then interview every household within the selected blocks. Clustering can reduce travel and administrative costs. In the example above, an interviewer can make
5405-429: Is sometimes introduced after the sampling phase in a process called "poststratification". This approach is typically implemented due to a lack of prior knowledge of an appropriate stratifying variable or when the experimenter lacks the necessary information to create a stratifying variable during the sampling phase. Although the method is susceptible to the pitfalls of post hoc approaches, it can provide several benefits in
5520-423: Is still conducted in a similar way to the post-enumeration survey employed in a traditional census. Other countries that have a population register use this as a basis for all the census statistics needed by users. This is most common among Nordic countries but requires many distinct registers to be combined, including population, housing, employment, and education. These registers are then combined and brought up to
5635-415: Is students who often have a term time and family address. Several countries have used a system known as short form/long form. This is a sampling strategy that randomly chooses a proportion of people to send a more detailed questionnaire to (the long form). Everyone receives the short-form questions. This means more data are collected, but without imposing a burden on the whole population. This also reduces
5750-428: Is taken from each stratum so that the rare target class will be more represented in the sample. The model is then built on this biased sample . The effects of the input variables on the target are often estimated with more precision with the choice-based sample even when a smaller overall sample size is taken, compared to a random sample. The results usually must be adjusted to correct for the oversampling. In some cases
5865-425: Is the procedure of systematically acquiring, recording, and calculating population information about the members of a given population , usually displayed in the form of statistics. 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
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#17330854508685980-546: The Han dynasty , and is still considered by scholars to be quite accurate. 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. Another census was held in AD 144. The oldest recorded census in India is thought to have occurred around 330 BC during
6095-408: The cause system of which the observed population is an outcome. In such cases, sampling theory may treat the observed population as a sample from a larger 'superpopulation'. For example, a researcher might study the success rate of a new 'quit smoking' program on a test group of 100 patients, in order to predict the effects of the program if it were made available nationwide. Here the superpopulation
6210-668: The nomarch , "whence he gained his living". Under the Ptolemies and the Romans several censuses were conducted in Egypt by government officials. There are several accounts of ancient Greek city states carrying out censuses. Censuses are mentioned several times in the Biblical narrative. God commands a per capita tax to be paid with the census for the upkeep of the Tabernacle . The Book of Numbers
6325-435: The 'population' Jagger wanted to investigate was the overall behaviour of the wheel (i.e. the probability distribution of its results over infinitely many trials), while his 'sample' was formed from observed results from that wheel. Similar considerations arise when taking repeated measurements of properties of materials such as the electrical conductivity of copper . This situation often arises when seeking knowledge about
6440-412: The 19th and 20th centuries collected paper documents which had to be collated by hand, so the statistical information obtained was quite basic. The government that owned the data could publish statistics on the state of the nation. The results were used to measure changes in the population and apportion representation. Population estimates could be compared to those of other countries. By the beginning of
6555-437: The 20th century, censuses were recording households and some indications of their employment. In some countries, census archives are released for public examination after many decades, allowing genealogists to track the ancestry of interested people. Archives provide a substantial historical record which may challenge established views. Information such as job titles and arrangements for the destitute and sick may also shed light on
6670-460: 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
6785-492: The approach best suited (or most cost-effective) for each identified subgroup within the population. There are, however, some potential drawbacks to using stratified sampling. First, identifying strata and implementing such an approach can increase the cost and complexity of sample selection, as well as leading to increased complexity of population estimates. Second, when examining multiple criteria, stratifying variables may be related to some, but not to others, further complicating
6900-414: The basis for a PPS sample of size three. To do this, we could allocate the first school numbers 1 to 150, the second school 151 to 330 (= 150 + 180), the third school 331 to 530, and so on to the last school (1011 to 1500). We then generate a random start between 1 and 500 (equal to 1500/3) and count through the school populations by multiples of 500. If our random start
7015-417: The burden on the statistical office. Indeed, in the UK until 2001 all residents were required to fill in the whole form but only a 10% sample was coded and analysed in detail. New technology means that all data are now scanned and processed. During the 2011 Canadian census there was controversy about the cessation of the mandatory long-form census; the head of Statistics Canada , Munir Sheikh , resigned upon
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#17330854508687130-457: The castle of La Rábita. In the sixteenth century Portocarrero Luis Zapata bought the population to the Crown, Dona Juana, also receiving the award of city status. After the expulsion of the Moors in 1570 began the repopulation of the Alpujarra with Castile, Galicia and Leon, but Albuñol did not occur until the seventeenth century. In 1834 he became head of the judicial district of the same name, currently
7245-438: 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. An accurate census can empower local communities by providing them with the necessary information to participate in local decision-making and ensuring they are represented. The importance of
7360-536: The census is that it represents the entire statistical universe, down to the smallest geographical units, of a country or region. Planners need this information for all kinds of development work, including: assessing demographic trends; analysing socio-economic conditions; designing evidence-based poverty-reduction strategies; monitoring and evaluating the effectiveness of policies; and tracking progress toward national and internationally agreed development goals." In addition to making policymakers aware of population issues,
7475-467: 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." 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
7590-474: The census of agriculture for development is that it gives a snapshot of the structure of the agricultural sector in a country and, when compared with previous censuses, provides an opportunity to identify trends and structural transformations of the sector, and points towards areas for policy intervention. Census data are used as a benchmark for current statistics and their value is increased when they are employed together with other data sources. Early censuses in
7705-563: The census of agriculture, users need census data to: 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. 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
7820-454: 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
7935-564: 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. Censuses in Egypt first appeared in the late Middle Kingdom and developed in the New Kingdom Pharaoh Amasis , according to Herodotus , required every Egyptian to declare annually to
8050-515: The combination of data from registers, surveys and other sources. 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
8165-522: 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
8280-437: The criterion in question, instead of availability of the samples). Even if a stratified sampling approach does not lead to increased statistical efficiency, such a tactic will not result in less efficiency than would simple random sampling, provided that each stratum is proportional to the group's size in the population. Third, it is sometimes the case that data are more readily available for individual, pre-existing strata within
8395-426: The data to adjust for the sample design, particularly in stratified sampling . Results from probability theory and statistical theory are employed to guide the practice. In business and medical research, sampling is widely used for gathering information about a population. Acceptance sampling is used to determine if a production lot of material meets the governing specifications . Random sampling by using lots
8510-415: The design, and potentially reducing the utility of the strata. Finally, in some cases (such as designs with a large number of strata, or those with a specified minimum sample size per group), stratified sampling can potentially require a larger sample than would other methods (although in most cases, the required sample size would be no larger than would be required for simple random sampling). Stratification
8625-446: The dwelling are accessed. As a preliminary to the dispatch of forms, census workers will check for any address problems on the ground. While it may seem straightforward to use the postal service file for this purpose, this can be out of date and some dwellings may contain several independent households. A particular problem is what is termed " communal establishments ", a category that includes student residences, religious orders, homes for
8740-461: 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. 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
8855-400: The election result for that electoral division. The reported sample counts yield a fairly accurate indicative result with a 95% confidence interval at a margin of error within 4-5%; ELD reminded the public that sample counts are separate from official results, and only the returning officer will declare the official results once vote counting is complete. Successful statistical practice
8970-579: The entire population) with appropriate contact information. For example, in an opinion poll , possible sampling frames include an electoral register and a telephone directory . A probability sample is a sample in which every unit in the population has a chance (greater than zero) of being selected in the sample, and this probability can be accurately determined. The combination of these traits makes it possible to produce unbiased estimates of population totals, by weighting sampled units according to their probability of selection. Example: We want to estimate
9085-483: 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 coordinate international practices. The UN 's Food and Agriculture Organization (FAO), in turn, defines
9200-548: The federal government's decision to do so. The use of alternative enumeration strategies is increasing but these are not as simple as many people assume and are only used in developed countries. The Netherlands has been most advanced in adopting a census using administrative data . This allows a simulated census to be conducted by linking several different administrative databases at an agreed time. Data can be matched, and an overall enumeration established allowing for discrepancies between different data sources. A validation survey
9315-548: The fifteenth century. Despite being a small town, Albuñol has several festivities throughout the year. Patronal Feast of St. Patrick on March 17 held by the town's streets the procession of the patron of Albuñol along with San Jose. Fiesta de San Marcos April 25, protector of cattle. Summer Fair: the first weekend of August. Cattle Fair: from 30 October to 1 November. Castles In particular it celebrates its Patronal Fiesta in honor of San Pedro from 27 to 29 June. (La Rábita): Fiesta de San Isidro Labrador, May 15, Feast of San Juan which
9430-413: The first to the k th element in the list. A simple example would be to select every 10th name from the telephone directory (an 'every 10th' sample, also referred to as 'sampling with a skip of 10'). As long as the starting point is randomized , systematic sampling is a type of probability sampling . It is easy to implement and the stratification induced can make it efficient, if the variable by which
9545-423: 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
9660-443: 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. A census can be contrasted with sampling in which information
9775-457: The headquarters is located in Motril. Among the traditions of the town is very Arriagada craft activities in the area such as manufacturing esparto or other materials. It is also called the great tradition of winemaking in the area, unique for its taste and graduation. Among the monuments of the town, one of the fundamentals is the parish church which is dedicated to St Patrick. The building dates from
9890-428: The high end and too few from the low end (or vice versa), leading to an unrepresentative sample. Selecting (e.g.) every 10th street number along the street ensures that the sample is spread evenly along the length of the street, representing all of these districts. (If we always start at house #1 and end at #991, the sample is slightly biased towards the low end; by randomly selecting the start between #1 and #10, this bias
10005-785: The historical structure of society. Political considerations influence the census in many countries. In Canada in 2010 for example, the government under the leadership of Stephen Harper abolished the mandatory long-form census. This abolition was a response to protests from some Canadians who resented the personal questions. The long-form census was reinstated by the Justin Trudeau government in 2016. As governments assumed responsibility for schooling and welfare, large government research departments made extensive use of census data. Population projections could be made, to help plan for provision in local government and regions. Central government could also use census data to allocate funding. Even in
10120-466: The identification of individuals in marginal populations; 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. The statistical information in
10235-499: 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. According to the United Nations Population Fund (UNFPA), "The information generated by
10350-403: The list is ordered is correlated with the variable of interest. 'Every 10th' sampling is especially useful for efficient sampling from databases . For example, suppose we wish to sample people from a long street that starts in a poor area (house No. 1) and ends in an expensive district (house No. 1000). A simple random selection of addresses from this street could easily end up with too many from
10465-524: The mid 20th century, census data was only directly accessible to large government departments. However, computers meant that tabulations could be used directly by university researchers, large businesses and local government offices. They could use the detail of the data to answer new questions and add to local and specialist knowledge. Nowadays, census data are published in a wide variety of formats to be accessible to business, all levels of government, media, students and teachers, charities, and any citizen who
10580-403: The north (expensive) side of the road, and the even-numbered houses are all on the south (cheap) side. Under the sampling scheme given above, it is impossible to get a representative sample; either the houses sampled will all be from the odd-numbered, expensive side, or they will all be from the even-numbered, cheap side, unless the researcher has previous knowledge of this bias and avoids it by
10695-497: The one ordered by the second Rashidun caliph , Umar . The Domesday Book was undertaken in AD 1086 by William I of England 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 . The first national census of France ( L'État des paroisses et des feux )
10810-478: The population. For example, researchers might be interested in examining whether cognitive ability as a predictor of job performance is equally applicable across racial groups. Simple random sampling cannot accommodate the needs of researchers in this situation, because it does not provide subsamples of the population, and other sampling strategies, such as stratified sampling, can be used instead. Systematic sampling (also known as interval sampling) relies on arranging
10925-540: The problems of overcount and undercount and the coherence of census enumerations with other official sources of data. For instance, during the 2020 U.S. Census, the Census Bureau counted people primarily by collecting answers sent by mail, on the internet, over the phone, or using shared information through proxies. These methods accounted for 95.5 percent of all occupied housing units in the United States. This reflects
11040-498: The reign of Emperor Chandragupta Maurya under the leadership of Chanakya and Ashoka . The English term is taken directly from the Latin census , from censere ("to estimate"). 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. Beginning in the middle republic, it
11155-405: The right situation. Implementation usually follows a simple random sample. In addition to allowing for stratification on an ancillary variable, poststratification can be used to implement weighting, which can improve the precision of a sample's estimates. Choice-based sampling is one of the stratified sampling strategies. In choice-based sampling, the data are stratified on the target and a sample
11270-403: The sample designer has access to an "auxiliary variable" or "size measure", believed to be correlated to the variable of interest, for each element in the population. These data can be used to improve accuracy in sample design. One option is to use the auxiliary variable as a basis for stratification, as discussed above. Another option is probability proportional to size ('PPS') sampling, in which
11385-418: The sample will not give us any information on that variation.) As described above, systematic sampling is an EPS method, because all elements have the same probability of selection (in the example given, one in ten). It is not 'simple random sampling' because different subsets of the same size have different selection probabilities – e.g. the set {4,14,24,...,994} has a one-in-ten probability of selection, but
11500-439: The sampling of a batch of material from production (acceptance sampling by lots), it would be most desirable 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 usually possible or practical. There is no way to identify all rats in the set of all rats. Where voting is not compulsory, there is no way to identify which people will vote at
11615-446: The selection probability for each element is set to be proportional to its size measure, up to a maximum of 1. In a simple PPS design, these selection probabilities can then be used as the basis for Poisson sampling . However, this has the drawback of variable sample size, and different portions of the population may still be over- or under-represented due to chance variation in selections. Systematic sampling theory can be used to create
11730-448: The set {4,13,24,34,...} has zero probability of selection. Systematic sampling can also be adapted to a non-EPS approach; for an example, see discussion of PPS samples below. When the population embraces a number of distinct categories, the frame can be organized by these categories into separate "strata." Each stratum is then sampled as an independent sub-population, out of which individual elements can be randomly selected. The ratio of
11845-517: The size of this random selection (or sample) to the size of the population is called a sampling fraction . There are several potential benefits to stratified sampling. First, dividing the population into distinct, independent strata can enable researchers to draw inferences about specific subgroups that may be lost in a more generalized random sample. Second, utilizing a stratified sampling method can lead to more efficient statistical estimates (provided that strata are selected based upon relevance to
11960-530: The standard of a statistical register by comparing the data from different sources and ensuring the quality is sufficient for official statistics to be produced. A recent innovation is the French instigation of a rolling census program with different regions enumerated each year so that the whole country is completely enumerated every 5 to 10 years. In Europe, in connection with the 2010 census round, many countries adopted alternative census methodologies, often based on
12075-429: The study population according to some ordering scheme and then selecting elements at regular intervals through that ordered list. Systematic sampling involves a random start and then proceeds with the selection of every k th element from then onwards. In this case, k =(population size/sample size). It is important that the starting point is not automatically the first in the list, but is instead randomly chosen from within
12190-455: The third by Karl Friedrich Wilhelm Dieterici in 1859. 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. Sampling (statistics) In statistics , quality assurance , and survey methodology , sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within
12305-528: The total income of adults living in a given street. We visit each household in that street, identify all adults living there, and randomly select one adult from each household. (For example, we can allocate each person a random number, generated from a uniform distribution between 0 and 1, and select the person with the highest number in each household). We then interview the selected person and find their income. People living on their own are certain to be selected, so we simply add their income to our estimate of
12420-441: The total. But a person living in a household of two adults has only a one-in-two chance of selection. To reflect this, when we come to such a household, we would count the selected person's income twice towards the total. (The person who is selected from that household can be loosely viewed as also representing the person who isn't selected.) In the above example, not everybody has the same probability of selection; what makes it
12535-416: The variance between individual results within the sample is a good indicator of variance in the overall population, which makes it relatively easy to estimate the accuracy of results. Simple random sampling can be vulnerable to sampling error because the randomness of the selection may result in a sample that does not reflect the makeup of the population. For instance, a simple random sample of ten people from
12650-417: Was 137, we would select the schools which have been allocated numbers 137, 637, and 1137, i.e. the first, fourth, and sixth schools. The PPS approach can improve accuracy for a given sample size by concentrating sample on large elements that have the greatest impact on population estimates. PPS sampling is commonly used for surveys of businesses, where element size varies greatly and auxiliary information
12765-443: Was abandoned, with the contract being sold to Brazil. The 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
12880-524: Was designed to elicit basic information about the nature of the land and the life of its peoples. The replies, known as " relaciones geográficas ", were written between 1579 and 1585 and were returned to the Cronista Mayor in Spain by the Council of the Indies. 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;
12995-570: Was not appreciated that these lists were heavily biased towards Republicans and the resulting sample, though very large, was deeply flawed. Elections in Singapore have adopted this practice since the 2015 election , also known as the sample counts, whereas according to the Elections Department (ELD), their country's election commission, sample counts help reduce speculation and misinformation, while helping election officials to check against
13110-518: Was undertaken in 1328, mostly for fiscal purposes. It estimated the French population at 16 to 17 million. In the 15th century, the Inca Empire had a unique way to record census information. The Incas did not have any written language but recorded information collected during censuses and other numeric information as well as non-numeric data on quipus , strings from llama or alpaca hair or cotton cords with numeric and other values encoded by knots in
13225-489: Was usually carried out every five years. It provided a register of citizens and their property from which their duties and privileges could be listed. It is said to have been instituted by the Roman king Servius Tullius in the 6th century BC, at which time the number of arms-bearing citizens was supposedly counted at around 80,000. When the Romans conquered Judea in AD 6, the legate Publius Sulpicius Quirinius organized
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