1. Quality information

Self-identified assessment 

Welsh language data from Census 2021 comes from a self-assessment of ability. The Census 2021 question asked people to assess their ability to:

  • understand spoken Welsh

  • speak Welsh

  • read Welsh

  • write Welsh

Everyone will assess their own language skills differently. This means that two people with the same skills in Welsh language may give different answers about their ability.

It could also be an assessment of another person's ability if someone is answering on behalf of someone else. For example, a parent could be answering on behalf of a child. The parent may not know how well a child can understand, speak, read, or write Welsh.  

Select all that apply

For the question "Can you understand, speak, read or write Welsh?", we asked people to select all that apply for each listed skill. Not everyone will have read this instruction and they may have selected only one box.

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2. Further research

The Welsh Government and Office for National Statistics (ONS) are jointly working on a research plan to improve understanding of main sources and administrative data sources used to produce statistics about the Welsh language. This research will include Census 2021 estimates on Welsh language skills.

In October 2023, Welsh Government published the first report based on analysis of data from individuals in Wales who had responded to Census 2021 and one of our household surveys, the Labour Force Survey (LFS). This report looks at differences between reporting of Welsh language skills across the two data sources. It was produced in partnership between analysts from Welsh Government, Administrative Data Research Wales (ADR Wales) and ONS. The analysis was conducted in the Integrated Data Service (IDS) and is the first published output using the IDS.

For more information on this research please see the joint work plan on coherence of Welsh language skills available on the Welsh Government website.

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Contact details for this Methodology

Census customer services 
Telephone: +44 1392 444972