Issues and corrections

Details of issues and corrections to published Census 2021 data.

In line with Census Office’s revisions and corrections policy, thorough quality checks will take place on all census statistics which are released. Census Office may occasionally need to revise statistics and update information.

Details of where Census Office have discovered an issue with or correction to Census 2021 data are contained in the log for easy reference.

DI002: Accommodation type

Type: Issue

Date added: 15 December 2022

Comment

Household question 7 on the 2021 Census questionnaire asks ‘What type of accommodation is this?’ with tick box options given for recording a response.

Census Office has noted differences in classification declared by a small number of respondents for accommodation type when compared to the accommodation type recorded by Land and Property Services (LPS) for the address. This can be explained by census respondents favouring selecting ‘semi-detached’ instead of ‘terraced (including end-terrace)’ for end-terrace properties.

It is consistent with previously published Office for National Statistics (ONS) research comparing responses to the 2011 Census question ‘What type of accommodation is this?’ with data trained surveyors have reported to the Valuation Office Agency (VOA).  The ONS research identified a preference for 2011 Census respondents to define their property as ‘semi-detached’ instead of ‘end-terrace’ in approx. 3% of cases.

This issue is related to the classification selected by respondents and does not affect the total number of properties recorded.

DI001: Rounding difference between census data published in May 2022 and September 2022

Type: Issue

Date added: 22 September 2022

Comment

The main statistics demography tables that form part of the ‘Census 2021 main statistics for Northern Ireland (phase 1)’ release supersede the population and household estimates published in the 24 May 2022 release, which reported statistics solely at the Northern Ireland level.

In May 2022, NISRA published rounded Northern Ireland level population and household estimates. At that time, the dataset was still being subjected to a number of final statistical procedures; these statistical procedures have been applied to the census database, and the unrounded statistics are now available. A number of figures at the Northern Ireland level (when rounded to the nearest 100) differ from the May figures as detailed in Table 1 and 2. 

Table 1: Comparison with May 2022 rounded figures – persons
Category May 2022 rounded figure Finalised rounded figure
Usual residents 1,903,100 1,903,200
Usual residents:
30-34 years
126,000 126,100
Usual residents:
55-59 years
129,200 129,300
Usual residents:
60-64 years
113,000 113,100
Females:
30-34 years
64,800 64,900
Females:
40-44 years
62,900 63,000
Females:
50-54 years
67,000 66,900
Males 936,200 936,100
Males:
40-44 years
59,300 59,200
Males:
60-64 years
55,400 55,300
Table 2: Comparison with May 2022 rounded figures – households
Category May 2022 rounded figure Finalised rounded figure
Households 768,900 768,800