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Many statistics collected by Statistics New Zealand are based on our geographic pattern. This pattern defines areas such as regional councils, territorial authorities, electorates and urban areas. The entire pattern is built from meshblocks. A meshblock is the smallest area used to collect and present statistics.
The size of a meshblock depends primarily on the number of people and type of area covered. Generally, meshblocks in rural areas have a population of around 60 people, while in urban areas meshblocks are roughly the size of city blocks and contain approximately 110 people. The meshblock pattern changes slightly every year, but for most statistical purposes a five-year update to coincide with each census is sufficient. At the time of the 2006 Census of Population and Dwellings there were 41,376 meshblocks and 1,927 area units.
Meshblocks are used as building blocks, aggregating to larger areas such as area units, urban areas, territorial authorities and regional councils.
The diagram below illustrates the geographic hierarchy.
The maintenance of the meshblock pattern is ongoing and constant. The meshblock pattern is archived annually to ensure that an annual pattern is available. When created, meshblocks are allocated a unique seven-digit number. They are arranged in a numeric sequence from north to south and west to east throughout the length and breadth of New Zealand. When a meshblock is split, the final two digits of its original number are changed. Statistics New Zealand maintains a concordance file to ensure that boundaries relating to earlier meshblock patterns can also be generated.
Statistics New Zealand would normally align meshblock boundaries to cadastral or physical features which are obvious on the ground, though some historic boundaries are anomalous. Administrative boundaries such as territorial authorities are defined legally by survey office plans.
Meshblock boundaries are amended for many reasons. Considerations when creating new boundaries include:
- communities of interest
- changing cadastral patterns
- size of meshblocks - number of dwellings (preferably between 10 and 50); population (preferably less than 200)
- physical access to properties
- physical size and shape of meshblock, for ease of enumeration
- distinguishing between residential/commercial/industrial areas
- obvious natural and manmade boundaries, such as rivers and motorways
- keeping large complexes, such as retirement homes and schools, within a single meshblock
- keeping environmentally sensitive areas together
- requests from external users, such as central/local government and other organisations
- requests from internal users, such as census (for enumeration) and household surveys (as the meshblock pattern underpins the geographical boundaries their sampling frame)
It is not always possible to create a meshblock boundary anywhere to accomodate requests, because Statistics New Zealand needs to consider how the meshblock change will affect all the other legally defined geographic boundaries such as regional council, constituency and Māori constituency, territorial authority, ward, community board, subdivisions, Māori wards and General and Māori electorates. Statistics New Zealand works closely with the Electoral Representation Commission, Local Government Commission, territorial authorities, regional councils and district health boards during boundary revision exercises to ensure meshblock boundaries are placed in suitable places for electoral purposes. Statistics NZ also maintains boundaries for other external users such as the health domiciles (used in health funding) and police areas, districts and stations.
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