National Ethnic Population Projections

1953

First set of national Māori population projections produced. The base population was the estimated de facto population of Māori ethnicity of New Zealand at 31 March 1952.

1993

First set of national Pacific population projections produced. The base population was the census usually resident population count of Pacific ethnic group (but excluding people with Māori ethnicity) of New Zealand at 5 March 1991.

1995 (September)

New birth and death registration forms introduced carrying a revised question on ethnicity. Previously the ethnic questions asked for the degree of Māori or "Pacific Island" blood, if any. The new ethnic question instructs the respondent to "tick as many circles as needed to show which ethnic group(s)...". This resulted in a number of changes:

• the ethnic concept is now self-identified ethnicity (previously Māori and Pacific respondents were classified by their 'degree of blood')
• ethnic vital statistics are now available for a wider range of ethnic groups (previously information was only sought for Māori and Pacific groups)
• ethnic data is now directly available for newborn babies and the deceased (in both cases this was previously derived from their parent's ethnicity)
• multiple response to the ethnicity question is now possible (previously the degree of Māori or Pacific blood, but not both, could be identified)
• non-response to the ethnicity question can now be quantified.

See also Births and Deaths Profiles.

1996

Population concept for all demographic estimates, projections and indices changed from 'de facto' to 'resident'. Population estimates based on the de facto population concept (the estimated de facto population) include visitors from overseas, but made no adjustments for net census undercount or residents temporarily overseas. Population estimates based on the resident population concept (the estimated resident population) include adjustments for net census undercount and residents temporarily overseas, but exclude overseas visitors. The reference date for projections is shifted from 31 March to 30 June.

1998

First set of national Asian population projections produced. The base population was the estimated resident population of Asian ethnic group of New Zealand at 30 June 1996.

2003

First set of national European population projections produced. The base population was the estimated resident population of European ethnic group of New Zealand at 30 June 2001.

2015

The first time, Statistics NZ applied a stochastic (probabilistic) approach to producing ethnic population projections. This follows the application of a stochastic approach to the national population projections (2011-base and 2014-base) and national labour force projections (2006-base, August 2012 update).

Nature of Projections

These projections are not predictions. The projections should be used as an indication of the overall trend, rather than as exact forecasts. The projections are updated every 2–3 years to maintain their relevance and usefulness, by incorporating new information about demographic trends and developments in methods.

The projections are designed to meet both short-term and long-term planning needs, but are not designed to be exact forecasts or to project specific annual variation. These projections are based on assumptions made about future fertility, mortality, migration, and inter-ethnic mobility patterns of the population. While the 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.

The projections do not take into account non-demographic factors (eg war, catastrophes, major government and business decisions) which may invalidate the projections.

Projections of ethnic populations are more uncertain than projections of the total population for several reasons:

• Ethnic identification can change over time. See the inter-ethnic mobility section for further explanation.

• There are greater difficulties in establishing past trends in fertility, mortality, and migration. Different ethnicities can be reported in different collections (eg birth registration form, death registration form, census form), which makes deriving ethnic-specific fertility and mortality rates problematic. Furthermore, the measurement of ethnicity has changed over time in many collections, while it is not captured at all in some collections (eg international travel and migration data).

• Ethnic populations are not mutually exclusive because people can and do identify with more than one ethnicity. People are not asked to prioritise their ethnic responses. Hence, Statistics NZ includes people in each of their reported ethnic groups.

• Births to parents of different ethnicities add complexity. The parents may consider the child to belong to one or more of their ethnicities, or indeed to another ethnicity.

• There is greater future uncertainty about the components of population change. For example, it is uncertain whether the fertility and mortality of different ethnicities will converge, and if so, at what pace. Assumptions about future migration, notably for people of Asian and Pacific ethnicities, are particularly susceptible to changes in migration patterns.

Statistics NZ incorporates these factors into its methodology for ethnic population projections and has developed stochastic population projections to illustrate uncertainty. However, it is because of these factors that ethnic population projections are currently limited to the four broad ethnic groups and the 25-year projection period.

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 (eg 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 (eg 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 (eg net census undercount). It also includes uncertainty associated with the post-censal components of population change (eg 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.

Projection Assumptions

Projection assumptions are formulated after analysis of short-term and long-term historical trends, recent trends and patterns observed in other countries, and government policy. The 'National ethnic population projections, projection assumptions, 2013(base)–2038' table in NZ.Stat provides a summary of the assumptions for each ethnic group.

Which projections should I use?

The projections are summarised by percentiles, which indicate the probability distribution for any projected characteristic. Users can make their own judgement as to which projections are most suitable for their purposes. At the time of release, the 50th percentile (or median) indicates an estimated 50 percent chance that the actual result will be lower, and a 50 percent chance that the actual result will be higher, than this percentile. The median is equivalent to the 'medium' (or mid-range) projection provided in previous deterministic projections. The 25th percentile indicates an estimated 25 percent chance that the actual result will be lower, and a 75 percent chance that the actual result will be higher, than this percentile. It is important to note, however, that the estimates of uncertainty are themselves uncertain.

Statistics New Zealand, Ministry of Health, Government Planners/Local Body Planners, Ministry of Education, Consultants, Private Businesses

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