About this dataset

This dataset provides Census 2021 estimates that classify usual residents in Wales by their overall Welsh language skills. The estimates are as at Census Day, 21 March 2021.

National Park data are created by plotting unique properties as identified by their Unique Property Reference Number or postcodes into National Park boundaries current at December 2022. This differs from the OA best fit methodology used for other geographic level data.

Protecting personal data

Sometimes we need to make changes to data if it is possible to identify individuals. This is known as statistical disclosure control. In Census 2021, we:

• Swapped records (targeted record swapping), for example, if a household was likely to be identified in datasets because it has unusual characteristics, we swapped the record with a similar one from a nearby small area. Very unusual households could be swapped with one in a nearby local authority.
• Added small changes to some counts (cell key perturbation), for example, we might change a count of four to a three or a five. This might make small differences between tables depending on how the data are broken down when we applied perturbation.

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