What steps were taken to adjust census counts for under-enumeration in 1991?

The government allocates much of its resources on the basis of sub-national population counts so it is important that these are as accurate as possible. To ensure this, the Office of Population Censuses and Surveys (OPCS) made adjustments to the census counts of 'usual residents' to take account of under-enumeration, producing a set of mid-1991 population estimates for every district in the UK. These were based on a series of separate adjustments

• The national undercount estimated by the 1991 CVS was distributed to districts in ways that gave plausible sex ratios, in line with the country as a whole (adding in of people from missed or mis-classified dwellings or missed from households that did respond),and a range of other data sources e.g. pensioner data from the Department of Social Security was used to enhance census counts of the elderly
• allowances were also made to take account of definitional differences e.g. students (counted at their home address in the Census) were moved to their term time-address
• finally, allowances were made for population changes between census day (April 21st) and mid-1991 (June 30th) i.e. births minus deaths and net migration

These corrected counts were provided only at district level. For those wanting to work at a smaller level of geography, further corrected estimates (down to ward and Enumeration District) were derived as part of the Estimating with Confidence Project [Note: This link opens in a new window] The Linking Census Through Time (LCT) service also provides adjusted counts for a wide range of social and employment characteristics. [Note: This link opens in a new window]