Subnational Family and Household Projections
Subnational Family and Household Projections
Stats NZ: Population Insights
Subnational Family and Household Projections indicate the future number and broad types of families and households usually living in New Zealand's 16 regional council areas (regions), 67 territorial authority areas (TAs), and 21 Auckland local board areas (LBAs). Three alternative projections (low, medium, and high) have been produced for each area, indicating probable outcomes based on different combinations of fertility, mortality, migration, and living arrangement type assumptions.
The family and household projections are derived from projections of population, by multiplying the projected population by assumed living arrangement type rates for each age-sex group. The projections of population by living arrangement type are subsequently aggregated to give projections of families (by broad family type) and households (by broad household type).
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.
Family and household projections provide an indication of future trends in the number and composition of families and households. The projections are used by community groups, businesses and government agencies, in planning and policy-making. The projections provide information on the changing characteristics of families and households, which are used to develop social policies in areas such as health, housing and education. For example, the ageing population and increasing single person households 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 families and households . 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.
Nature of Projections
Demographic 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. We based these projections on assumptions about future fertility, mortality, migration, and living arrangement type patterns of the population. Although the assumptions are carefully formulated to represent future trends, they are subject to uncertainty. Therefore, the projections should be used as guidelines and an indication of the overall trend, rather than as exact forecasts.
The projections do not take into account non-demographic factors (for example, war, catastrophes, or major government and business decisions) that may invalidate the projections. Demographic trends are monitored regularly and, when it is necessary, we revise projections to reflect new trends and to maintain their relevance and usefulness.
Only the medium projection has been formulated to produce demographically plausible results, by assessing both observed historical trends and likely future trends. Other projections may project significantly different numbers of male and female partners in couple-without-children and/or two-parent families. Although living arrangement type rates are formulated to account for changing social patterns, there is uncertainty about how different social patterns will interrelate and vary by age-sex and/or birth cohort. Relevant social patterns include changes in:
- age of cohabitation and/or marriage
- fertility rates, timing of childbearing, and average family size
- morbidity and mortality rates
- rates of partnership formation, including re-partnering, and dissolution
- propensity of young adults to stay in the parental home
- propensity and ability of people to live alone
- presence of other relatives (for example, extended family) and non-related individuals (for example, boarders) in a household
- study, work, and shared-care arrangements where people are associated with more than one household
- geographic location and mobility of the population
- external migration patterns, including students from overseas
- affordability of tertiary education, housing, and healthcare
- ethnic mix of the New Zealand population.
Stats NZ, Ministry of Health, Government Planners/Local Body Planners, Ministry of Education, Consultants, Private Businesses.
The 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.
A new 'propensity' method is used to produce subnational family and household projections, superseding the 1996-base subnational household projections which used a 'household head' method. The new series include, for the first time, projections of families by broad family type and projections of broad household types.
A new 'sequential propensity' method and a modelled approach to derive subnational family and household projections based on 2001–2018 Census data, superseding the 2013-base 'propensity method'. The new method enables delivery of national and subnational (regions, territorial authority and Auckland local boards) family and household projections at the same time.