The once-a-decade exercise to take a snapshot of the country in one 24-hour period is a major challenge. This time it is complicated by the Covid-19 pandemic, but the ONS is confident there will be high levels of compliance and the vast majority of households will answer questions online.
Some pockets of the population are hard to reach, for reasons that include language barriers, mistrust of government, worries about personal data and aversion to or difficulty with form-filling.
The overall response in 2011 was 94%, but among some BAME households it was up to 10 percentage points lower. Hundreds of community engagement advisers have been recruited to work with different ethnic and religious groups this time.