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Statistical geography hierarchy

The statistical geography hierarchy has four levels:

  • meshblock
  • statistical area 1 (SA1)
  • statistical area 2 (SA2)
  • urban rural.

Each statistical geography is nested within the level above. SA1s are built by joining meshblocks together and SA2s are built by joining SA1s together. Within the urban rural geography, urban areas are defined at SA2 level and rural settlements are defined at SA1 level.

Meshblock

Meshblocks are the smallest geographic units for which statistical data is reported by Stats NZ. A meshblock is a defined geographic area, varying in size from part of a city block to a large area of rural land. Meshblocks are contiguous: each meshblock borders on another to form a network covering all of New Zealand, including coasts and inlets. The meshblock classification extends out to New Zealand’s 200 nautical mile exclusive economic zone (EEZ) and is digitised to the 12 mile (19.3km) limit. Meshblocks have an ideal size range of 30–60 dwellings (around 60–120 residents).

The primary purposes of the meshblock classification are:

  • to provide a small, relevant and flexible building block geography for aggregation into other statistical geographies
  • to ensure geographic boundaries can be physically identified and located on the ground by alignment with geographic or physical features, or with the cadastre
  • as the lowest-level building block, to form the basis of New Zealand’s electoral system, by which it defines electorates and polling areas for both parliamentary and local government elections.

The Statistical standard for meshblock defines meshblocks and describes their primary purposes. The standard sets out requirements and guidelines for the creation and maintenance of the meshblock classification and Stats NZ’s responsibilities for maintaining the standard.

As the lowest-level building block, the meshblock classification is primarily an input geography which supports the electoral system, survey enumeration, and higher-level geographies. Statistical outputs are limited to single variables, such as census population and dwelling counts, to which confidentiality rules are applied to prevent the identification of individuals living in sparsely populated areas.

The meshblock classification

The meshblock classification is a flat classification, and in 2018 contains 53,589 meshblocks – 53,573 digitised and 16 non-digitised. Meshblocks are not named and have seven-digit codes.

See Classification of Meshblock for more information.

Statistical areas

Statistical area geographies are aggregations of meshblocks optimised to be of similar population sizes to enable the release of low-level data. They are non-administrative areas that are in between meshblocks and territorial authorities in size. Statistical areas either define or aggregate to define urban rural areas, territorial authorities, and regional councils.

The statistical area 1 (SA1) geography is a new output geography that allows the release of more detailed information about population characteristics than is available at the meshblock level.

The statistical area 2 (SA2) geography replaces the area unit geography. Although the concepts for SA2s are generally the same as the area unit concepts, the boundaries and names have changed to reflect changes in land use and population patterns since the 1992 geography was created.

Statistical area 1 (SA1)

SA1 definition

The main purpose of the SA1 geography is to provide an output geography that allows the release of more low-level data than is available at the meshblock level. Built by joining meshblocks, SA1s have an ideal size range of 100–200 residents, and a maximum population of about 500. This is to minimise suppression of population data in multivariate statistics tables.

The SA1 should:

  • form a contiguous cluster of one or more meshblocks 
  • be either urban, rural, or water in character 
  • be small enough to: 
    • allow flexibility for aggregation to other statistical geographies 
    • allow users to aggregate areas into their own defined communities of interest
  • form a nested hierarchy with statistical output geographies and administrative boundaries. It must:
    • be built from meshblocks 
    • either define or aggregate to define SA2s, urban rural areas, territorial authorities, and regional councils.

SA1 population size

SA1s generally have a population of 100–200 residents, with some exceptions:

  • SA1s with nil or nominal resident populations are created to represent remote mainland areas, unpopulated islands, inland water, inlets, or oceanic areas.
  • Some SA1s in remote rural areas and urban industrial or business areas have fewer than 100 residents. 
  • Some SA1s that contain apartment blocks, retirement villages, and large non-residential facilities have more than 500 residents.

The SA1 classification

The SA1 classification is a flat classification and in 2018 contains 29,889 SA1s – 29,873 digitised and 16 non-digitised. SA1s are not named. SA1 codes have seven digits starting with a ‘7’ and are numbered approximately north to south. As new SA1s are created, they are given the next available numeric code.

See Classification of Statistical Area 1 for more information.

Statistical area 2 (SA2)

SA2 definition

The main purpose of the SA2 geography is to provide an output geography for higher aggregations of population data than can be provided at the SA1 level. The SA2 geography aims to reflect communities that interact together socially and economically. In populated areas, SA2s generally contain similar-sized populations.

The SA2 should:

  • form a contiguous cluster of one or more SA1s 
  • excluding exceptions below, allow the release of multivariate statistics with minimal data suppression
  • capture a similar type of area, such as high-density urban areas, farmland, wilderness areas, and water areas 
  • be socially homogeneous and capture a community of interest. It may have, for example: 
    • a shared road network
    • shared community facilities
    • shared historical or social links, or 
    • socio-economic similarity
  • form a nested hierarchy with statistical output geographies and administrative boundaries. It must: 
    • be built from SA1s
    • either define or aggregate to define urban rural areas, territorial authorities, and regional councils.

In major urban areas, an SA2 or a group of SA2s often approximates a single suburb. A small urban area containing up to 5,000 residents may be represented by a single SA2. In rural areas, rural settlements are included in their respective SA2 with the surrounding rural area.

SA2 population size

SA2s in city council areas generally have a population of 2,000–4,000 residents while SA2s in district council areas generally have a population of 1,000–3,000 residents.

In rural areas, many SA2s have fewer than 1,000 residents because they are in conservation areas or cover large areas that have sparse populations, for example, Fiordland.

SA2s have been created in urban areas where there is significant business and industrial activity, for example ports, airports, industrial, commercial, and retail areas. These areas have fewer than 1,000 residents and are useful for analysing business demographics, labour markets, and travel-to-work patterns.

Some SA2s with nil or nominal populations have been created to ensure that the SA2 geography covers all of New Zealand and aligns with New Zealand’s topography and local government boundaries. These types of SA2s are described below.

Water SA2s

SA2s with nil or nominal resident populations are created to represent inland water, inlets or oceanic areas and include: 

  • inland lakes larger than 50 km2 (lakes smaller than 50 km2 are included with the surrounding land SA2) 
  • harbours larger than 40 km2
  • major ports 
  • other non-contiguous inlets and harbours defined by territorial authority
  • contiguous oceanic areas defined by regional council.

Island SA2s

Stewart Island and Chatham Islands are represented by separate SA2s.

To minimise suppression of population data, small islands with nil or low populations close to the mainland are generally included with their adjacent land-based SA2.

SA2s have been created for populated single islands or groups of islands that are some distance from the mainland, or to separate large unpopulated islands from urban areas. These SA2s are:

  • Three Kings Islands 
  • Barrier Islands (includes Great Barrier and Little Barrier Islands, and other nearby islands) 
  • Gulf Islands (includes Motutapu, Rangitoto, and other islands in the Hauraki Gulf) 
  • Waiheke Island (six SA2s)
  • Islands Thames Coromandel District
  • Islands Bay of Plenty Region (Motiti Island, Mayor Island, Moutohora Island, and White Island) 
  • Bare Island (in the Hawke’s Bay region but outside the territorial authority area)
  • Matakana Island 
  • Kapiti Island 
  • Mana Island 
  • Islands Tasman District (Best Island, Bell Island, and Rabbit Island).

Alignment with territorial authority and regional council boundaries

In rural areas where territorial authority boundaries straddle regional council boundaries, SA2s have been created to maintain the statistical geography and administrative area hierarchy. These SA2s each have fewer than 200 residents and are: Arahiwi, Tiroa, Rangataiki, Kaimanawa, Taharua, Te More, Ngamatea, Whangamomona, and Mara.

The SA2 classification

The SA2 classification is a flat classification and in 2018 contains 2,253 SA2s – 2,237 digitised and 16 non-digitised.

Each SA2 is a single geographic entity with a name and a numeric code. The name refers to a geographic feature or a recognised place name or suburb. In some instances where place names are the same or very similar, the SA2s are differentiated by their territorial authority, for example, Gladstone (Invercargill City) and Gladstone (Carterton District).

SA2 codes have six digits. North Island SA2 codes start with a ‘1’ or ‘2’ and South Island SA2 codes start with a ‘3’. They are numbered approximately north to south within their respective territorial authorities. In 2018, the last two digits of each code is 00, and when SA2 boundaries change in the future, only the last two digits of the code will change, to ensure the north–south pattern is maintained.

See Classification of Statistical Area 2 for more information.

Urban rural

The urban rural geography classifies New Zealand into areas that share common urban or rural characteristics. It is used to disseminate a broad range of Stats NZ’s social, demographic, and economic statistics.

The urban rural classification separately identifies urban areas, rural settlements, other rural areas, and water areas. The urban areas represent densely developed spaces, and encompass residential, commercial, and other non-residential urban land uses. Rural settlements, other rural areas, and bodies of water represent areas not included within an urban area.

The urban rural indicator classifies urban, rural, and water areas by type. Urban areas are classified by population size; rural areas are classified as rural settlements or rural other; and water areas are classified as inland water, inlet, or oceanic.

Urban areas and rural settlements are delineated by the inspection of aerial imagery, local government land designations on district plan maps, address registers, property title data, and any other available information. However, because the underlying meshblock pattern is used to define the geographies, boundaries may not align exactly with local government land designations or what can be seen in aerial images.

Urban areas are built from SA2s. Rural and water areas are built from SA1s.

Urban areas

Urban areas are statistically defined areas with no administrative or legal basis. They are characterised by high population density with many built environment features where people and buildings are located close together for residential, cultural, productive, trade, and social purposes.

Urban areas are delineated using the following criteria. They: 

  • form a contiguous cluster of one or more SA2s
  • contain an estimated resident population of more than 1,000 people and usually have a population density of more than 400 residents or 200 address points per square kilometre
  • have a high coverage of built physical structures and artificial landscapes such as:
    • residential dwellings and apartments 
    • commercial structures, such as factories, office complexes, and shopping centres
    • transport and communication facilities, such as airports, ports and port facilities, railway stations, bus stations and similar transport hubs, and communications infrastructure
    • medical, education, and community facilities
    • tourist attractions and accommodation facilities
    • waste disposal and sewerage facilities
    • cemeteries
    • sports and recreation facilities, such as stadiums, golf courses, racecourses, showgrounds, and fitness centres
    • green spaces, such as community parks, gardens, and reserves 
  • have strong economic ties where people gather together to work, and for social, cultural, and recreational interaction 
  • have planned development within the next 5–8 years.

Urban areas are further classified by the size of their estimated resident population:

  • major urban area – 100,000 or more residents
  • large urban area – 30,000–99,999 residents
  • medium urban area – 10,000–29,999 residents
  • small urban area – 1,000–9,999 residents.

Urban boundaries are independent of local government and other administrative boundaries, that is, an urban area may be contained within one or more local government region or administrative areas. The Richmond urban area, which is mainly in the Tasman District, is the only urban area that crosses territorial authority boundaries, and includes an SA2 that is in the Nelson City territorial authority.

Rural areas

Rural areas represent land-based areas outside urban areas. They are classified as rural settlements or other rural.

Rural settlement

Rural settlements are statistically defined areas with no administrative or legal basis. A rural settlement is a cluster of residential dwellings about a place that usually contains at least one community or public building.

Rural settlements are delineated using the following criteria. They:

  • form a contiguous cluster of one or more SA1s
  • contain an estimated resident population of 200–1,000, or at least 40 residential dwellings
  • represent a reasonably compact area, or have a visible centre of population with a population density of at least 200 residents per square kilometre or 100 address points per square kilometre
  • contain at least one community or public building, such as a church, school, or shop.

The SSGA18 urban rural geography includes rural settlements that were previously called rural centres in NZSAC92, rural settlements that were previously part of an NZSAC92 urban area, and newly identified rural settlements that meet the above criteria.

Rural settlements are usually combined with the surrounding rural area to form an SA2, in order to reach the target SA2 population size. In some instances, the settlement and the SA2 may have the same name, for example, West Melton rural settlement is part of the West Melton SA2.

Other rural

Other rural areas are the mainland areas and islands located outside urban areas or rural settlements. Other rural areas include land used for agriculture and forestry, conservation areas, and regional and national parks.

Other rural areas are defined by territorial authority.

Water

To ensure that the urban rural geography covers all of geographic New Zealand, bodies of water are classified separately, using the land/water demarcation classification described in the Statistical standard for meshblock. These water areas are not named, and are defined by territorial authority or regional council.

The water classes include:

  • inland water – non-contiguous, defined by territorial authority
  • inlets (which also includes tidal areas and harbours) – non-contiguous, defined by territorial authority 
  • oceanic – non-contiguous, defined by regional council.

The urban rural classification

The urban rural classification is a flat classification. Each urban area and rural settlement is a single geographic entity with a name and a numeric code. In 2018, there are 178 urban areas and 400 rural settlements, based on 2013 Census data and 2018 population projections. Some urban areas and rural settlements may be reclassified when 2018 Census data is available.

Other rural areas, inland water areas, and inlets are defined by territorial authority; oceanic areas are defined by regional council; and each have a name and a numeric code.

Urban rural codes have four digits. North Island locations start with a ‘1’, South Island codes start with a ‘2’, and oceanic codes start with a ‘6’.

See Classification of urban rural for more information.

The urban rural indicator

The urban rural indicator classifies urban, rural, and water areas by type.

The indicators, with their codes in brackets, are: 

  • urban area – urban major (11), urban large (12), urban medium (13), urban small (14) 
  • rural area – rural settlement (21), rural other (22)
  • water – inland water (31), inlet (32), oceanic (33).

See Classification of urban rural indicator for more information.

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