Working Party on the Application of New Technology to Population Data
Fourth meeting
6-9 July 1999
Manila

1. Executive Summary
2. Electronic Map Providers
3. Use of maps within Statistics New Zealand
4. Level of detail and accuracy required
5. Frequency of Use
6. Source of the Maps Used
7. Services Which Should Be Provided internally
8. Skills and Tools needed to be maintained
9. External Mapping Knowledge Required by Statistics New Zealand

The use of maps within the statistical process is clearly an important issue. Statistics New Zealand relies on very detailed maps to help identify places people live for the 5-yearly Census of Population enumeration. These maps not only help to improve the coverage of the census, but are also fundamental to the allocation of enumerator workloads to minimise the risk of gaps and duplications occurring in the enumeration. 

The fundamental basis of small area statistics is vitally dependent on the accurate identification of the physical location of addresses. Without recourse to detailed maps the quality of small area statistics would be placed at serious risk.

The need for large numbers of street maps for survey purposes should be known well in advance and should be able to be produced more efficiently by an external map provider. The external supplier should maintain the meshblock pattern, as their software contains data layers sufficient to permit the geocoding of individual address details, it appears logical that the software should also be employed for this purpose. 

The production of maps for output purposes has different drivers. At present Supermap3 is used for this purpose. Given that map generation is the primary function of this software and the presentation quality satisfactory to the majority of Statistics New Zealand's customers, Supermap3 should continue to be employed until GIS software is required to satisfy the more detailed and expanding output needs.

In 1996, the Department of Land and Survey Information was divided into two separate organisations, Land Information New Zealand and Terralink. Land Information New Zealand now has responsibility for policy matters related to land information and maintains the digital cadastral database on which all New Zealand land parcel details are detailed. Terralink has assumed responsibility for the commercial activities such as the production of printed and electronic maps. Terralink is a state owned enterprise that competes in the commercial world for profit.

Terraview is an electronic mapping software package. This tool contains up to 40 separate layers of data the user may view but cannot edit. Terraview contains layers detailing topographic data such as road, rivers, railways lines etc. It also contains statistical boundary data such as meshblock, electoral district, territorial authority boundaries. Other layers contain land parcel data such as street number, deposit plan and lot number, registered landowner etc.

Terraview contains all of the usual functions associated with mapping software. The user may pan around the map, zoom into or out of an area to obtain a more detailed or broader view. The user may move directly to a specific address by using the search facilities, which are integrated within the software.

If a user has data that they would like included within Terraview, Terralink (for an agreed charge) will digitise the user's data and include it within the product as a separate layer. Once the layer has been included within Terraview, other layers may be used to increase the value of the user's data. 

The meshblock is the smallest geographic area used by Statistics New Zealand for the collection, processing and dissemination of data. The meshblock is the building block for aggregation into larger areas such as area units (equivalent to suburbs) and urban areas. The New Zealand wide system of standard meshblocks was established in 1976. 

Meshblocks vary in both population and area size, from an extensive tract of sparsely populated rural land to a city block. When the meshblock pattern was established in 1976, urban meshblocks contained an average of 150-200 people, while rural meshblocks generally contained 150-200 people to suit the workload allocated to individual enumerators. Subsequent division of meshblocks to recognise areas where there are large numbers of businesses and changes in population patterns have resulted in meshblock population counts smaller than when they were first established.

Originally the meshblock boundaries were identifiable on the ground. Wherever possible they followed road patterns river courses or other prominent physical features. While this practice is still followed, there is an increasing tendency of aligning meshblock boundaries to legally defined cadastral boundaries. Aligning to cadastral boundaries simplifies the legal definition of administrative areas such as electoral districts and local government areas. Such alignment also alleviates the geocoding problem caused by industrial units and residential sections being divided between two meshblocks.

Maps are used within Statistics New Zealand in a variety of work areas for a wide range of purposes. A survey of conducted in January 1999 revealed that maps are used for five principal functions.

In addition to the above functions, there are a number of additional minor uses for maps within Statistics New Zealand. Maps are used to define potential areas of population and dwelling growth, to ascertain current local and regional government boundaries and to assign country codes for migration and overseas trade purposes. Area unit and urban area maps are also used to determine both statistical and administrative boundaries. 

Mapping detail and accuracy level requirements vary from work area to work area within Statistics New Zealand. For ease of analysis input and output mapping requirements have been separated. Input requirements have been further disaggregated by degree of detail required.

The Geographic Frame (GF) team requires the most detailed maps. This area is responsible for maintaining the actual meshblock boundaries and arranges with Land Information New Zealand (LINZ) for these boundaries to be digitised:

1. to the nearest millimetre (although current technology does not permit this level of accuracy); and
2. to the nearest metre.

The GF team adjusts meshblock boundaries at the finest level possible to ensure consistency and accuracy with the Digital Cadastral Database (DCDB) maintained by LINZ. To verify that LINZ has correctly aligned meshblock boundaries, the GF team use maps that are as accurate as possible, depicting land parcels, road boundaries and street names and numbers. 

A number of work areas require maps containing extensive detail but not to the level of exactness described above. Building Consents, Business Frame, Classifications and Standards, Demography, Economic Surveys, Household Surveys and Population and Census 2001 all require a moderate level of mapping detail. General requirements include land parcels showing individual buildings, street name and number and clearly defined statistical and administrative boundaries sufficient to identify the meshblock of an individual business or dwelling. 

Business Statistics, Government Sector, Migration and Overseas Trade require maps that contain a minimum of detail. The prime requirement appears to be that the maps clearly identify administrative and statistical boundaries. Migration and Overseas Trade require atlases to identify countries. 

Maps that appear in Statistics New Zealand's publications vary widely in the level of detail displayed. Perhaps the most detailed are the maps that appear in the Yearbook, which show considerable topographic detail. Other published maps all depict considerably less information. Statistical or thematic maps are generally provided at territorial authority or occasionally area unit level with little or no land parcel, street and topographic detail. However, ultimately maps will be required whereby statistical data can be displayed according to customer or issue defined areas.

The frequency with which various work areas use maps is directly related to the level of detail required. Users of very detailed maps such as the Business Frame and Geographic Frame, use maps extensively every day. Similarly, Household Surveys and Population and Census 2001, use maps every day during the collection of the survey. 

Work areas with lesser mapping detail requirements tend to use maps on a less frequent basis depending on the context of the work, e.g. weekly or monthly.

Maps at the most detailed level, i.e. land parcel, are generated in-house using the Terralink sponsored mapping software known as Terraview. Statistics New Zealand currently has 12 licences for the use of this software that also enables the maps to be printed. A colour plotter/printer is located on the GF section for this purpose. A decision was made to out-source the production of the Census 2001 enumeration maps primarily because of the scale and cost of the operation. 

All other maps used within Statistics New Zealand are purchased from external suppliers. These mainly comprise Terralink maps, Universal Business Directory maps, etc. Statistics New Zealand sells maps produced by Terralink i.e. NZMS series maps and 1996 Census area unit maps.

 All output incorporating maps produced containing statistical data is generated within Statistics New Zealand using Supermap3 software. We have accumulated the non-thematic bit map image maps that appear in Statistics New Zealand publications. 

A few guiding principles are necessary before any decision can be made regarding internal versus external mapping service provision. Mapping is not within the core business of Statistics New Zealand, which should not be seen as a provider of maps or a mapping service, which can be provided more efficiently by other organisations.

 Guiding principles employed in this analysis are:

The key issue is whether or not Statistics New Zealand's mapping requirements are sufficiently subject matter specific that only Statistics New Zealand has the level of detailed understanding of our own requirements to produce the required maps. In some instances this is clearly the situation but in others this is not so.

The Geographic Frame has highly specialised mapping needs that cannot be easily satisfied by an external provider. Meshblock boundary split, nudge and digital checks necessitate the generation of highly detailed maps at land parcel level on a frequent but irregular basis. These maps are required as the work progresses and are best produced directly by the section itself. 

The Geographic Frame also uses maps to assist with the five-yearly redesign of Primary Sampling Units for the Household Labour Force survey. Maps are also needed to verify that meshblock splits and nudges have been correctly actioned by LINZ. Maps also assist the Geographic Frame team to verify data received from various external sources relating to new street names and numbers. 

The Business Frame also has highly specialised mapping needs that require land parcel detail. To maintain the geographic references on the Business Frame access to land parcel detail is essential. The mapping needs of the Business Frame are at times intense while at other times, somewhat sporadic.

The Population and Census 2001 team has a high volume and detailed mapping requirement once every five years. Household Surveys have a recurring need for maps directly related to areas selected for survey interviewing. The volume is generally not as great as, but the detail approximates, Census 2001 requirements. Statistics New Zealand has neither the equipment nor the qualified personnel to produce such large volumes of maps.

The remaining areas within Statistics New Zealand either have less detailed mapping requirements or a lower level of demand. Generally these requirements should be and currently are met by external providers.

Thematic maps designed to display small area statistics in a pictorial manner require the map generator to manipulate the original data in a number of ways. The provision of official statistics (which may contain unit record data) to an external mapping service provider to generate a thematic map is not desirable. Given that the number of thematic maps generated by Statistics New Zealand is not large and that existing mapping software (Supermap3) is quite adequate for this purpose, there appears to be no useful gain to Statistics New Zealand from seeking an external service for thematic map production.

The generation of high volumes of maps is not part of Statistics New Zealand's core business. Maps generated for survey enumeration or interviewing purposes are commonly of significant volume and generally reasonably consistent in detail requirements. A dedicated map supplier should be able to support this type of high volume map production better. However, the ad hoc generation of maps for specific purposes that require a quick turnaround should be capable of being produced internally. On many occasions the need for a map showing considerable detail can be critical to the decision making process. Delays in the delivery of maps in these situations could be detrimental to the quality of small area statistics.

A number of map users including, Business Frame, Classifications and Standards, Geographic Frame, Household Surveys and Population and Census 2001 require maps of a highly specific nature. These maps are not generally produced for public use by mapping suppliers. However, a number of external suppliers do have the capacity to produce the type of map required by the above work areas. The critical factor is the time required by external suppliers to deliver the maps to exacting specifications. If the map is required urgently, provided it is of an ad hoc nature, the map could be generated within Statistics New Zealand.

Statistics New Zealand currently has 12 licences for the software product Terraview. The licence comprises DCDB data licences, data customisation charges, and monthly updates, meshblock boundary changes and annual meshblock pattern digitisation costs. In addition, Statistics New Zealand incurs salary costs associated with the meshblock maintenance process. However, the bulk of these expenses are recouped from the sale of digital meshblock and other area boundaries to third parties.

There are numerous features incorporated within Terraview that enable the meshblock pattern to be maintained in a cost effective and efficient environment. The meshblocking of rural addresses with no site number such as farms and rural building consents is made infinitely easier with the inclusion of two Quotable Value New Zealand data layers. These layers, containing valuation number and property owner data, are critical to improving match rates and assigning correct meshblocks to electors. 

Terraview also provides 16 layers containing various digitised boundary patterns including meshblock '96, '99 and rolling, area unit, ward, territorial authority, regional council, Maori and general electoral districts etc. Additional software features include more layers showing topographical features, place names, street, land parcel boundaries and address details. All features improve the quality and content of Statistics New Zealand's Geographic Frame, meshblocking capability and ultimately result in improved quality of small area statistics.

Statistics New Zealand runs Terraview on Pentium 200 PCs in a networked environment. A colour plotter/printer, capable of printing A0 size maps, is located on the Geographic Frames section and is used to produce maps showing splits and nudges for action by LINZ. This printer is also used to print maps required by customers (external and internal) on an ad hoc basis. It was recently used to produce all of the 1,769 PSU (primary sampling unit) maps for the redesigned sample for the Household Labour Force Survey. Maps may also be printed on an ordinary laser printer in black and white however; the lack of colour makes the identification of different boundaries particularly difficult.

Thematic maps are generated using Supermap3 software. Very few work areas within Statistics New Zealand currently use thematic maps as part of their output. Thematic maps are more commonly used within the Regional and International Statistics Division as large amounts of data related to small areas are best presented in map form. 

There is a corporate need for mapping skills to maintain quality frames, regional data, enumeration and output presentation. Previous attempts to find an external training course of relevance to the mapping skill requirements needed by Statistics New Zealand staff have to date proved to be unsuccessful. However, Statistics New Zealand may wish to consider the development of a course that provides a basic introduction to the following skills. 

One of the basic fundamental requirements is the ability to read and interpret maps. This is not as simple as it sounds based on the number of people in the street who, with a map in their hand, ask directions of passers-by! Map-reading skills are an essential facet of map production and meshblock maintenance. Quality small area data depends on the correct allocation of meshblocks, which in turn is frequently dependent on the map reading ability of the data processor.

When determining meshblock boundary placement, it is extremely important to have a knowledge and understanding of communities of interest.

This type of skill is invaluable when assigning meshblocks to businesses, dwellings and people. The ability to investigate all possible alternatives and reference material thoroughly and efficiently is an important attribute to ensure accurate small area statistics and also when maintaining the meshblock pattern.

The ability to manipulate data stored within database systems is important as the majority of electronic mapping is actioned via databases. Statistics New Zealand requires people with a sound basic knowledge of how to join tables together and understand the fundamental principles behind the logic of database technology.

Within Statistics New Zealand in general a reasonable standard of computer literacy is necessary. Mapping is no exception, in fact an even higher skill level is required because of the unique nature of computerised mapping. Knowledge of technical terms associated with mapping such as scaling, panning and zooming must be well understood.

While a lack of understanding of GIS technology will not prevent Statistics New Zealand staff from generating and understanding computerised maps, it is clear that this knowledge will enable them to be more effective in their work and dealing competently with customer requirements by understanding the power of GIS technology and its application within the community.

Again the lack of understanding of GIS data formats will not prevent Statistics New Zealand staff from generating and understanding computerised maps, but a basic knowledge of digital formats will enable them to better understand the nature of the electronic mapping component of their work.

Statistics New Zealand needs to maintain in-house knowledge sufficient to ensure that mapping services are appropriately out-sourced to competent suppliers who will provide a competitive service. The following knowledge needs to be maintained by Statistics New Zealand.

Statistics New Zealand does have a need to maintain an up-to-date knowledge of the technological developments relating to computerised map production. This is an area of modern technology that is advancing rapidly in terms of capacity and capability. 

To ensure that the most appropriate hardware and software is being used effectively and efficiently by Statistics New Zealand, there is a very clear need to ensure that knowledge in this area is well maintained.

The most effective means of maintaining appropriate knowledge of computerised mapping issues is to attend GIS seminars. The Spatial Information Research Centre holds these annually in November at Otago University in Dunedin. It would be advisable for a representative of Statistics New Zealand to attend these seminars.

Statistics New Zealand is a member of AURISA, which is a group representing both Australian and New Zealand organisations and individuals with an interest is spatial elements, including mapping. AURISA conducts an annual weeklong conference with workshops in a different centre each year. The 1998 AURISA conference was held in Perth. 

It is essential to be able to understand the technical terms used by mapping suppliers e.g. topology, appellation etc., as well as understand the needs of map users. Without this knowledge Statistics New Zealand staff will be unable to determine which external provider is capable of providing the best service. 

To decide whether to contract services externally or provide an in-house service Statistics New Zealand needs to maintain an up-to-date knowledge of external provider service capabilities. Technology in this area is developing rapidly and GIS capabilities improve on a regular basis. It is very important that Statistics New Zealand maintains regular contact with external service providers.

Statistics New Zealand needs to be aware of the relative charging policies of external service providers. This information is essential to determine which contractor will deliver the service for the most reasonable cost. Mapping service providers do have considerably differing pricing structures and Statistics New Zealand needs to be aware of how to obtain a value for money service.