National Ethnic Population Projections

Abstract National Ethnic Population Projections provide projected 'European or Other (including New Zealander)', Māori, Asian, and Pacific ethnic populations of New Zealand, based on different combinations of fertility, mortality, migration, and inter-ethnic mobility assumptions.

Demographic projections provide an indication of future trends in the size and composition of the population, labour force, families and households. The projections are used for community, business and government planning and policy-making in areas such as health, education, superannuation and transport. The projections are typically updated every two to three years.

Purpose Ethnic population projections are produced to assist local and ethnic communities, as well as central government, in planning and policy-making. The projections provide information on the changing characteristics and distribution of the population, which are used to develop social policies in areas such as health and education. For example, where different ethnic groups experience different health conditions, ethnic population projections can help identify likely future service needs.

The projections are neither predictions nor forecasts. They provide an indication of possible future changes in the size and composition of the ethnic populations. While the projection assumptions are formulated from an assessment of short-term and long-term demographic trends, there is no certainty that any of the assumptions will be realised. Each ethnic population consists of all people who identify with ethnicities within that ethnic group.

It is important to note that these ethnic populations are not mutually exclusive because people can and do identify with more than one ethnicity. People who identify with more than one ethnicity have been included in each ethnic population that they identify with.

Methodology A special cohort component method has been used to derive the ethnic population projections. By this method, the base population is projected forward by adding new birth cohorts and calculating the effect of deaths, migration and inter-ethnic mobility within each age-sex group according to specified mortality, migration and inter-ethnic mobility assumptions. New birth cohorts are generated by applying specified fertility assumptions to the female population of childbearing age, and specified paternity assumptions to the male population.

The method differs from the conventional cohort component method in two respects:

• For each ethnic group, births are projected separately for women, and for men where the mother is not of that ethnic group. For example, Māori births have been projected separately for Māori women, and for Māori men where the mother is non-Māori.

• The projections allow for population change due to inter-ethnic mobility (i.e. people changing their ethnic identification over time).

Fertility and mortality assumptions are derived for the purpose of projecting each population and should not be used as a precise measure of fertility or mortality differentials between ethnic groups.

Ethnic Concept The ethnic concept used in these projections is the ethnic group or groups that people identify with or feel they belong to. Ethnicity is self-perceived and people can identify with more than one ethnicity. Ethnicity is different from ancestry, birthplace, and nationality. For example, people can identify with Māori ethnicity although they may not be descended from a Māori ancestor. Conversely, people may choose to not identify with Māori ethnicity even though they are descended from a Māori ancestor.

See Review of the Measurement of Ethnicity or the ethnicity classification for more information about ethnicity including information about the Statistical Standard for Ethnicity 2005.

European or Other Projections have been derived for the combined 'European or Other (including New Zealander)' ethnic group. Sufficient demographic data is available to enable projection assumptions to be derived for the combined ethnic group, but not for the separate 'European' or 'Other (including New Zealander)' ethnic groups defined in level one of the ethnicity classification. This approach is consistent with Guidelines for Using Ethnicity Data: 2006 Census. If a person belongs to both the 'European' and 'Other' ethnic groups, they have only been counted once. Almost all people in the 'Other' ethnicity group belong to the 'New Zealander' sub-group.

Base population These projections have as a base the estimated resident population of each ethnic group at 30 June 2013. This population was based on the census usually resident population count of each ethnic group at 5 March 2013 with adjustments for:

• non-response to the census ethnicity question
• net census undercount
• residents temporarily overseas on census night
• births, deaths, and net migration between census night (5 March 2013) and 30 June 2013
• reconciliation with demographic estimates at ages 0–9 years.

The 'Estimated resident population (ERP), adjustments to derive ERP at 30 June 2013 (from census usually resident population)' table in NZ.Stat provides a summary of the ERP and adjustments to derive ERP at 30 June 2013 for each ethnic group.

The ERP is the best available measure of the number of people of each ethnic group usually living in New Zealand. However, for projection purposes, some uncertainty in the base population has been assumed. This uncertainty is assumed to vary by age and sex, and arise from two broad sources:

• Census enumeration and processing. Coverage errors may arise from non-enumeration and mis-enumeration (e.g. residents counted as visitors from overseas, and vice versa), either because of deliberate or inadvertent respondent or collector error. Errors may also arise during census processing (e.g. scanning, numeric and character recognition, imputation, coding, editing, creation of substitute forms).

• Adjustments in deriving population estimates. This includes the adjustments applied in deriving the ERP at 30 June of the census year (e.g. net census undercount). It also includes uncertainty associated with the post-censal components of population change (e.g. estimates of births occurring in each time period based on birth registrations; changes in classification of external migrants between ‘permanent and long-term’ and 'short-term').

For each ethnic group, simulations of the base population are produced by drawing a random number sampled from a normal distribution with a mean of zero. For each simulation, a random number is multiplied by the assumed standard error for each age-sex then added to the base ERP.

For more information about the base population, refer to Population Estimates.