In the study of survey

Statistical survey

Survey methodology is the field that studies surveys, that is, the sample of individuals from a population with a view towards making statistical inferences about the population using the sample. Polls about public opinion, such as political beliefs, are reported in the news media in democracies....

 and census

Census

A census is the procedure of systematically acquiring and recording information about the members of a given population. It is a regularly occurring and official count of a particular population. The term is used mostly in connection with national population and housing censuses; other common...

 data

Data

The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

, microdata is information at the level of individual respondents. For instance, a national census might collect age, home address

Address (geography)

An address is a collection of information, presented in a mostly fixed format, used for describing the location of a building, apartment, or other structure or a plot of land, generally using political boundaries and street names as references, along with other identifiers such as house or...

, education

Education

Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

al level, employment

Employment

Employment is a contract between two parties, one being the employer and the other being the employee. An employee may be defined as:- Employee :...

 status, and many other variables, recorded separately for every person who responds; this is microdata.
Survey/census results are most commonly published as aggregates

Aggregate data

In statistics, aggregate data describes data combined from several measurements.In economics, aggregate data or data aggregates describes high-level data that is composed of a multitude or combination of other more individual data....

 (e.g. a region

Region

Region is most commonly found as a term used in terrestrial and astrophysics sciences also an area, notably among the different sub-disciplines of geography, studied by regional geographers. Regions consist of subregions that contain clusters of like areas that are distinctive by their uniformity...

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.