This dataset provides census estimates for the number of usual residents in Northern Ireland for the census years 1851 - 2021 by broad age bands, and by sex.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

This dataset provides census estimates for the number of usual residents living in households in Northern Ireland for the census years 1851 - 2021. It also includes an estimate of the number of households and average household size.

The census collected information on the usually resident population of Northern Ireland on census day (21 March 2021). Initial contact letters or questionnaire packs were delivered to every household and communal establishment, and residents were asked to complete online or return the questionnaire with information as correct on census day. Special arrangements were made to enumerate special groups such as students, members of the Travellers Community, HM Forces personnel etc. The Census Coverage Survey (an independent doorstep survey) followed between 12 May and 29 June 2021 and was used to adjust the census counts for under-enumeration.

The quality assurance report can be found here

Census 2021 was the first census with a digital-first design, encouraging participants to respond online rather than on a paper questionnaire. Support was given to people who could not respond online, including paper questionnaires, telephone contact centres, field force support, and an extended collection period.

Topics covered in the 2021 UK Census included:

• demography and migration
• ethnic group, national identity, language and religion
• labour market and travel to work
• housing
• education
• health, disability, and unpaid care
• Welsh and other languages
• UK armed forces veterans
• sexual orientation and gender identity.

The 2021 Census: Safeguarded Household Microdata Sample dataset consists of a random sample of 1% of households from the 2021 Census and contains records for all individuals within these sampled households. It includes records for 263,729 households and 606,210 persons. These data cover England and Wales only. This sample allows linkage between individuals in the same household.  The lowest level of geography is Wales and regions within England. It contains 56 variables and a low level of detail. This is a new ONS product following user feedback from the 2011 Census.

Census Microdata

Microdata are small samples of individual records from a single census from which identifying information have been removed. They contain a range of individual and household characteristics and can be used to carry out analysis not possible from standard census outputs, such as:

• creating tables using bespoke variable combinations
• investigating specific combinations of variables or categories in a high level of detail
• conducting non-tabular statistical analyses on record-level data.

The microdata samples are designed to protect the confidentiality of individuals and households. This is done by applying access controls and removing information that might directly identify a person, such as names, addresses and date of birth. Record swapping is applied to the census data used to create the microdata samples. This is a statistical disclosure control (SDC) method, which makes very small changes to the data to prevent the identification of individuals. The microdata samples use further SDC methods, such as collapsing variables and restricting detail. The samples also include records that have been edited to prevent inconsistent data and contain imputed persons, households, and data values. To protect confidentiality, imputation flags are not included in any 2021 Census microdata sample.

Census 2021 was the first census with a digital-first design, encouraging participants to respond online rather than on a paper questionnaire. Support was given to people who could not respond online, including paper questionnaires, telephone contact centres, field force support, and an extended collection period.

Topics covered in the 2021 UK Census included:

• demography and migration
• ethnic group, national identity, language and religion
• labour market and travel to work
• housing
• education
• health, disability, and unpaid care
• Welsh and other languages
• UK armed forces veterans
• sexual orientation and gender identity.

The 2021 Census: Public Microdata Teaching Sample (England and Wales): 1% Sample: Open Access consists of a random sample of 1% of person records from Census 2021 for England and Wales. It includes records for 604,351 persons. This dataset is suitable for teaching of statistics and social sciences and contains 18 demographic variables and a respondent ID variable.

Archive of 1981 census aggregate data for England, Wales and Scotland, as made available originally on the Casweb (https://casweb.ukdataservice.ac.uk) platform.