1. Quality information

Legal partnership status

The census response data contained implausibly high numbers of people reporting to be in opposite-sex civil partnerships and same-sex marriages. We have corrected most of these apparent errors by using information from the relationship matrix question on the census questionnaire.

However, this correction is not possible where people do not live with their current or ex-partner. This means that we consider estimates for the legal partnership status “Separated”, “Divorced/dissolved”, and “Widowed/surviving partners” to be reliable. However, the disaggregation of those groups by opposite- and same-sex partnerships is not.

Be aware that we will not be producing separate estimates by opposite- and same-sex for the legal partnership status categories “Separated”, “Divorced/dissolved” and “Widowed/surviving partners” as part of our standard census results.

Inconsistency when comparing legal partnership status with household composition

The complexity of living arrangements coupled with the way people interpreted these questions may mean that relationships seen in the household may not appear to match legal partnership status. For example, there may be situations where people who have described themselves as never married or civil partnered are shown as living in “married couple families”.

Take care when interpreting census data on legal partnership status together with data drawn from the relationship matrix question on the census questionnaire, such as family type.

Passports held

The passports held question allowed respondents to select:

  • ”United Kingdom”
  • ”Ireland”
  • ”Other”

If they selected “Other”, they could write in the country for which they had a passport. Multiple ticks were allowed for this question. So, for example, people could be recorded as holding both a British and Irish passport. However, only the first written-in country was taken if the respondent wrote in more than one country under “Other”.

Short-term residents

The great majority of published census estimates relate to “usual residents”. The census also collects information on “short-term residents”. These are defined as people born outside the UK who were present in the UK on Census Day who intended to stay in the UK for less than 12 months, including the time they have already spent here. This population is relatively small (fewer than 200,000 people across England and Wales) and has not been adjusted to correct for any non-response.

Reliability of data at oldest ages

Any misreporting of date of birth by either the respondent, proxy completer or from scanning of paper returns is more likely to affect older ages where there are fewer actual records. We carried out estimation of non-response in Census 2021 for the age 90 years and over group as a whole. This means that there is less reliability in the estimates for single year of ages from age 90 years up to 100 years and over than for the group as a whole. When the adjustment process imputed new records to account for the estimated non-response, this was optimised across a number of characteristics rather than just single year of age. As such, where there are small numbers in single age groups, this can sometimes lead to unlikely looking age patterns at low-level geographies.

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Contact details for this Methodology

Census.customerservices@ons.gov.uk
Telephone: +44 1329 444972