The census is the most complete source of information about the population that we have. Every effort is made to include everyone. It is the only survey that provides a detailed picture of the entire population and is unique because it covers everyone at the same time and asks the same core questions everywhere. This makes it easy to compare different parts of the country.

However, no census is perfect and some people are inevitably missed. Office for National Statistics (ONS) will, therefore, use complex statistical techniques to adjust the 2021 Census counts for those people missed by the census.

The methods and quality assurance approach will be researched and developed in consultation with academics, statisticians, demographers and users of census data.

The result will be a suite of methods to process, clean, adjust and protect the census results.