Data Collection
Estimated private dwellings and households (2018-base)
Methodology
Estimated Private Dwellings
An estimate of all private dwellings in New Zealand at a given date.
This is a measure of the private dwelling stock in New Zealand and includes occupied and unoccupied dwellings. A private dwelling accommodates a person or a group of people, but is not available to the public. A private dwelling may be permanent or temporary. Permanent private dwellings include houses and flats; residences attached to a business or institution; and batches, cribs, and huts. Caravans, cabins, tents, and other makeshift dwellings that are the principal or usual residence of households are classified as temporary private dwellings.
This estimate includes permanent and temporary private occupied dwellings as well as private unoccupied dwellings. The estimate excludes non-private dwellings and dwellings under construction. This estimate makes no adjustment for private dwellings missed or counted more than once by the census (net census undercount).
The estimated private dwellings at a given date after a census also includes an adjustment for new dwellings, less an adjustment for dwellings that are demolished or destroyed.
Estimated private dwellings are available quarterly at the national level 'as at' each reference date (31 March, 30 June, 30 September, and 31 December) from 31 March 1991. Estimated private dwellings are also available quarterly for 'mean quarter ended' and 'mean year ended'.
Base
The base number of private dwellings are from the 1991, 1996, 2001, 2006 2013, and 2018 Censuses of Population and Dwellings. The estimated private dwellings within New Zealand is an estimate of all private dwellings in New Zealand at a given date.
This estimate includes permanent and temporary private occupied dwellings.
This estimate excludes non-private dwellings and dwellings under construction.
This estimate includes private unoccupied dwellings, for these estimates the assumption is that there is no net census undercount of private dwellings.
Method
The estimated private dwellings are based on information from the 1991, 1996, 2001 , 2006, 2013 , and 2018 Censuses of Population and Dwellings.
Building consents are used to indicate movements between quarters. The building consent data is lagged to allow for buildings to be completed. Prior to April 2013 this lag is six months. From April 2013 onward, the lag has been increased to nine months. The number of building consents issued for new residential dwellings (including conversion of non-residential buildings into private dwellings) was:
about 98,500 from 1 September 1990 to 31 August 1995 (when lagged by six months, this equates roughly to the period from census date 1991 to census date 1996)
about 116,100 from 1 September 1995 to 31 August 2000
about 132,500 from 1 September 2000 to 31 August 2005
about 133,300 from 1 September 2005 to 31 August 2012 (this time series is irregular, being a 7-year rather than the usual five year gap. Be careful when comparing trends)
about 123,200 from 1 June 2012 to 31 May 2017 (when lagged by nine months, this equates to roughly the period from census date 2013 to census date 2018).
The estimated increase in private dwelling numbers is calculated from building consents multiplied by a weighting factor. The weighting factor makes a net allowance for:
building consents not fulfilled
new dwellings not registered
existing dwellings being demolished or destroyed
conversion between private and non-private dwellings
existing dwellings being subdivided into multiple dwellings
existing dwellings being amalgamated into fewer dwellings.
The estimated weighting factors are:
0.907 for 1991–1996
1.012 for 1996–2001
0.933 for 2001–2006
0.875 for 2006–2013
0.863 for 2013-2018.
As there is no information on how this weighting factor may have varied during each previous period, for 2018-base estimates, it is kept constant at the factor implied by the change in estimates between the 1991 and 2018 Censuses of 0.910.
In summary, the quarterly private dwelling estimates are calculated by taking the private dwelling estimate from the previous quarter and adding building consents for the quarter (lagged nine months) multiplied by the weighting factor (WF):
EPD(qn) = EPD(qn-1) + BC(qn-3) x WF
where:
EPD = estimated private dwellings
q = quarter
n = time period
BC = building consents
WF = weighting factor
Estimated Households
An estimate of all households usually living in New Zealand at a given date.
A household consists of one person usually residing alone, or two or more people usually residing together in a private dwelling, therefore visitors are excluded. Households whose members are all away temporarily elsewhere in New Zealand and/or temporarily overseas are included.
Estimated households are available quarterly at the national level 'as at' each reference date (31 March, 30 June, 30 September, and 31 December) from 30 June 1991. Estimated households are also available quarterly for 'mean quarter ended' and 'mean year ended'.
Base
The base number of households is derived indirectly from the estimated resident population and the estimated living arrangement type rates for each age-sex group (derived for the Family and Household Projections). The estimated number of households at 30 June of the census year is equivalent to the census household count with adjustments for:
households temporarily absent within New Zealand
net census undercount
households temporarily overseas on census night
household change between census night and 30 June of the census year.
For more information about the base number of households, refer to Demographic Projections.
Method
In deriving the Family and Household Projections, the number of households at 30 June 1991, 1996, 2001 , 2006, 2013, and 2018 has been estimated. These estimates represent the start and end points for intermediate household estimates.
Similar to estimating the private dwellings, building consents are used to indicate movements between quarters. The building consent data is lagged to allow for buildings to be completed and become inhabited by households. Prior to April 2013 this lag is six months. From April 2013 onward, the lag has been increased to nine months.
The estimated increase in household numbers is calculated from building consents multiplied by a weighting factor. The weighting factor makes a net allowance for:
building consents not fulfilled
new dwellings not registered
existing dwellings being demolished or destroyed
existing dwellings becoming uninhabitable (e.g. fire damaged)
for changes in the ratio of occupied to unoccupied dwellings (e.g. caused by changes in the number of second homes or holiday homes).
The estimated weighting factors are:
0.892 for 1991–1996
0.738 for 1996–2001
0.943 for 2001–2006
0.734 for 2006–2013
1.117 for 2013–2018
As there is no information on how this weighting factor may have varied during each previous period, for 2018-base estimates, it is kept constant at the factor implied by the change in estimates between the 1991 and 2018 Censuses of 0.887.
In summary, the quarterly household estimates are calculated by taking the household estimate from the previous quarter and adding building consents for the quarter (lagged nine months) multiplied by the weighting factor (WF):
EH(qn) = EH(qn-1) + BC(qn-3) x WF
where:
EH = estimated households
q = quarter
n = time period
BC = building consents
WF = weighting factor
Tenure
Tenure of household refers to the nature of the occupancy of a private household in a dwelling at a given time. Tenure of household seeks to ascertain if the household rents or owns the dwelling and whether payment is made by the household for that right. It does not refer to the tenure of the land on which the dwelling is situated.
The estimated number of private dwellings and households by tenure is available quarterly from 1991 for three broad types:
owner-occupied (with or without a mortgage)
rented
provided free.
From 2006, owner-occupied includes dwellings held in family trusts.
The proportion of households in each tenure type was calculated from tenure of households in occupied private dwellings (excluding visitor-only dwellings) at the 1991, 1996, 2001, 2006, 2013 , and 2018 Censuses of Population and Dwellings. The tenure proportions for each quarter were calculated by linearly interpolating between the census tenure proportions.
From the 2018 Census onward the tenure proportions are held at their 2018 Census levels. This follows a period of flattening in the historical trend of reducing the owner-occupied proportions and increasing rented proportions.
The tenure of private dwellings is assumed to have the same distribution as the tenure of households in occupied private dwellings (excluding visitor-only households). No information on the tenure of unoccupied dwellings is available.
Estimates of private dwellings and households by tenure have been derived by applying tenure proportions to the respective estimates.
Tenure is influenced by a number of factors:
lifestyle
investment
economy
interest rates
patterns of family and household formation
job security
stage in life-cycle
cohort effects and population ageing
income and wealth distribution
social security and income support.
Notes
In the 2001 Census, a family trust was officially treated as 'not owned' and the help notes instructed respondents to mark 'no' to the ownership questions. However respondents may have indicated 'owned' because they did not read the help notes or still thought of themselves as owning the dwelling.
In the 2006 Census, the first tenure question was 'Do you, or anyone else who lives here, hold this dwelling in a family trust'. The family trust question then routed the respondent to further relevant tenure questions. From 2006, the dwelling and household estimates combines owner-occupied and dwellings held in family trusts to form tenure rates.
Although a dwelling held in a family trust is owned by the family trust, for the purposes of calculating owner-occupied levels within New Zealand, it is usual to combine households that own their dwelling with those that hold it in a family trust, as a percentage of all households in private dwellings. Private dwellings that are 'provided free' to households include dwellings owned by individuals, private trusts, businesses and government. Some people may therefore be living in private dwellings which they own but are classified as 'provided free' because they are owned by a private trust and/or provided free to some or all household members.
en-NZ
