Ethnic Fertility Estimates and Assumptions.

To implement population projections by ethnicity requires input of ethnic fertility rates, which vary considerably across groups. In most countries in which ethnic projections are produced, populations and vital components are classified by ethnicity. In the UK ethnic classifications have been employed in the decennial population censuses since 1991 and in the annual Labour Force Survey since 1980. But at registration of births, ethnicity is not recorded, though some health authorities may add ethnicity to birth occurrence records completed by an attending health professional. Country of birth is recorded on the birth certificate. However, this only signals ethnicity for foreign born mothers when ethnic groups are also made up of native-born mothers.

Therefore, we need to use indirect methods to make plausible estimates. Most researchers use official household surveys to estimate fertility rates from information about the composition of families with children resident in the households surveyed. Household surveys are samples and are rarely large enough to make reliable estimates of fertility rates for local areas. In our 2011-based projections, there is a need estimates for 389 local areas: 324 local authorities in England, 22 in Wales, 32 in Scotland and 11 in Northern Ireland. To achieve our estimated fertility rates, we employ a variety of data sources in addition to birth records and surveys, the most important of which is the decennial census which provides reliable counts of mother and infants by ethnicity at local scale.