The New Zealand Census
The most comprehensive count of the New Zealand population is derived from the Census of Population and Dwellings, conducted by Statistics New Zealand (Tatauranga Aotearoa) every 5 years. It is an official count of all people and dwellings New Zealand on Census night, and collects details of age, sex and other characteristics of New Zealand's population. The Statistics Act 1975 prescribes that a census be conducted every 5 years and provides a basic outline of Census content, though questions can and do change over time. The last New Zealand Census was conducted on 6 March 2018. It was the 34th census.
Census statistics are used as the basis for estimating the population at national and regional levels, for electoral purposes and the distribution of government funds. They are used by individuals and organisations in the public and private sectors for planning, administration, research and decision making.
Populations are estimated in various ways. It is important to understand how a population has been derived when you are using the data.
Census data in People & Places is predominantly based on usual residence data, while some household and dwelling information is based on place of enumeration.
Usual residence population
This population is derived from the Census. It is the place where a person usually lives, rather than the place where they were counted on Census night. Each person completing the Census is required to state their address of usual residence and this information is used to derive the Usual Residence population at the meshblock level.
Usual Residence is the main method of assessing the population in the Census, and information on this basis is available back to 2006. Because of this it is used as the default option in People & Places, and all data relating to individuals is presented based on their usual residence.
Enumerated population (Census night population)
This population counts people where they are on Census night, regardless of whether it is their usual address or not. Enumerated population is not used for most of the topics, however topics concerning households and dwellings have to use a form of enumerated data, as households which are away from their usual address on Census night don’t have their household characteristics recorded at their place of usual residence.
The information presented is based on detailed tables produced by Statistics New Zealand. Statistics NZ take confidentiality of data very seriously, and in 2018 they revised the basic rules to ensure that information is only used in aggregate, and no data about individuals can be ascertained from the Census data. There are now seven basic rules that determine sensitivity, when to suppress small cells, and add noise.
Table totals and subtotals will be internally consistent but discrepancies may be observed between tables cross-tabulating the same population by different variables. While randomisation compromises the table totals by making them appear inconsistent, this is the best available socio-demographic data at the suburb level. This level of compromise is not statistically significant and should not impact on decision makers making effective resource allocation and planning decisions.
No reliance should be placed on small cells as they are disproportionately impacted by random adjustment, respondent and processing errors.
Further information on confidentiality and random adjustment can be found in the Stats NZ fact sheet: Summary of 2018 Census confidentiality rules.
Census data are available at a variety of different geographic levels, for example, Region; Territorial Authority; Area Unit and Meshblock (a small local unit of 10-100 households). Often Census data geography doesn't match actual 'communities', 'suburbs' or 'service catchments' needed for effective decision making. While individual Meshblocks are small enough to be very useful, only limited data are available at this detailed level, and they need to be aggregated into higher level meaningful units.
The SSGA18 is New Zealand’s new official statistical geographic area standard. The framework enables statistical entities or units (e.g. dwellings, people or businesses) to be linked to the location where they are placed, live or work.
All the data Stats NZ collects is referenced to a specific place and time. Place can be any geography (e.g. city, lake, township or region), and the point of developing statistical geographical standards is to be able to consistently and accurately identify the size of change as well as where change occurs.
In 2018, the SSGA18 underwent its first major review since 1989. The new boundaries are designed to reflect current land use and spatial patterns. Privacy is still a pivotal requirement for Stats NZ, but the new geographies will also enable more finely grained information at the smaller area level.
The new statistical geographies are:
statistical area 1 (SA1)
statistical area 2 (SA2)
urban rural areas
People & Places Data are available down to SA2.
Meshblocks in NZ
- our smallest geography
- ideally around 30–60 dwellings (around 60–120 residents)
- identified by a seven-digit code
- 53,589 in total
- cover New Zealand and extend out to sea to cover NZ’s 200 nautical mile exclusive economic zone (EEZ)
SA1 geography in NZ (Statistical area 1)
- a new output geography
- ideally around 100–200 residents (maximum 500)
- identified by a seven-digit number starting with 7
- 29,889 SA1s in total
- an aggregation of meshblocks
SA2 geography in NZ (Statistical area 2)
- city SA2s usually have a population of 2,000–4,000 residents
- district council SA2s will usually have a population of 1,000–3,000 residents
- this geography level seeks to show the communities/neighbourhoods that combine socially and economically
- identified by a name (like the old census area units) and a numeric code which has 6 digits (starting with 1 or 2 in the North Island or 3 in the South)
- 2,253 in total
For more information
You can access more detail from Stats NZ Geographic boundary files.