In the study of survey and census

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

, microdata is information at the level of individual respondents. For instance, a national

census A census (from Latin ''censere'', 'to assess') is the procedure of systematically acquiring, recording, and calculating population information about the members of a given Statistical population, population, usually displayed in the form of stati ...

might collect age, home

address An address is a collection of information, presented in a mostly fixed format, used to give the location of a building, apartment, or other structure or a plot of land, generally using border, political boundaries and street names as references, ...

education Education is the transmission of knowledge and skills and the development of character traits. Formal education occurs within a structured institutional framework, such as public schools, following a curriculum. Non-formal education als ...

al level,

employment Employment is a relationship between two party (law), parties Regulation, regulating the provision of paid Labour (human activity), labour services. Usually based on a employment contract, contract, one party, the employer, which might be a cor ...

status, and many other variables, recorded separately for every person who responds; this is microdata.

Advantages

Survey/census results are most commonly published as aggregates (e.g. a

region In geography, regions, otherwise referred to as areas, zones, lands or territories, are portions of the Earth's surface that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and ...

al-level employment rate), both for privacy reasons and because of the large quantities of data involved; microdata for one census can easily contain millions of records, each with several dozen data items. However, summarizing results to an aggregate level results in information loss. For instance, if statistics for education and employment are aggregated separately, they cannot be used to explore a relationship between these two variables. Access to microdata allows researchers much more freedom to investigate such interactions and perform detailed analysis. Microdata from censuses is especially useful to study and evaluate patterns of social mobility. Its use allows to breach academic gaps on the topic. For example, a study of the 1900-1940 social mobility in the United States based on linked census data allowed to show that women impacted their descendants' social status, based on their marriage patterns and levels of education.

Availability

For this reason, some statistical organizations allow access to microdata for research purposes. Controls are generally imposed to limit the risk that this data may be abused or lead to loss of privacy. For example, the Integrated Public Use Microdata Series requires researchers to implement security measures, avoid redistribution of microdata, use microdata only for noncommercial research/education purposes, and not make any attempt to identify the individuals recorded. Names and fine-level geographical data are removed, some data items are altered as necessary to make it impossible to identify individuals, and small ethnic categories are merged. The International Household Survey Network has developed tools and guidelines to help interested statistical agencies improve their microdata management practices. The Microdata Management Toolkit is a DDI

metadata Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive ...

editor which is now used in about 80 countries, with the support of the Accelerated Data Program, implemented by the PARIS21 Secretariat, the

World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...

, and other partners, in the context of the Marrakech Action Plan for Statistics.

References

{{reflist Sampling (statistics) Censuses