GEOGRAPHY
The geographic planning of the 2004 Census started when the DNE received digitized aerial photographs covering all of Timor-Leste. They were produced by the Australian Defence Mapping and Geospatial Organization (DIGO) . The photographs are in GIS format (Geographic Information System). They were used as a starting point for identifying of census enumeration areas. One of the biggest tasks leading up to a census is the definition of enumeration areas. They are needed for identifying the areas within which census interviewers must work and to identify the location of households. A census mapping team was set up early in 2003 with the tasks of determining boundaries for enumeration areas and producing the large numbers of maps required for the field team.
Overview of Dili Enumeration Area
In July 2003 Pilot Census, it was discovered that having reliable and detailed maps of the country was not enough. A key issue was to ensure complete coverage in a country without addresses, street names, cadastre, etc. A new approach to locating houses on maps was needed, and the 2004 Census team decided to base its approach on the Global Position System (GPS).
GPS is a space-based radio-navigation system that provides users with accurate information about their position, speed and time anywhere in the world and in all weather conditions. The system has three components or segments. The first one is the space segment that consists of 24 GPS satellites that fly 6 circular orbits at an altitude of 20,100 km and with a period of 12 hours. The second component is the control segment which includes a master control monitor station at Falcon Air Force Base in Colorado Springs, Colorado, USA, and four monitor stations located on Hawaii, Ascension Island in the Atlantic Ocean, Diego Garcia Atoll in the Indian Ocean, and Kwajelein Island in the South Pacific Ocean. These stations monitor the GPS satellites. The third component is the user segment which is the GPS receiver. There are different models with different sizes, functions and capacities.
User Segment
GPS receivers record waypoints , which are latitude/longitude coordinates defining locations on the earth's surface. They can be downloaded from receivers to computers using an interface cable and special software.
Itwas decided to create an independent database containing the locations of all households by recording waypoints at the doorstep of each house in Timor-Leste. A system of stickers was devised to link the questionnaires to the households and both of them to the locations. The sticker was divided in two detachable parts and in each part was printed a unique 6-digit number. The enumerator was to stick the main part of the sticker on the house where the interview took place. This part of the sticker contained the logo of the census and the unique 6-digit identification number. The second part of the sticker, containing the same 6-digit number was to be glued on the census questionnaire for that household. This action linked the questionnaire to the household. The GPS operator then keyed the same number as the waypoint identification for that location in his or her receiver.
This linked the waypoint to that household and that questionnaire. In this way the location of household and each questionnaire could latter be linked. This was the key to the success of the operation.
As mentioned above, in July 2003 a pilot census was conducted. Two day training in background issues and use of GPS were provided to the enumerators. Upon completion of the field work two databases were created. First, a location database , with the waypoint numbers (sticker numbers) and latitude and longitude. Second, a content database , with sticker numbers (waypoint number) and the contents of the questionnaire. The two databases were combined using the common field: waypoint and sticker numbers.
It soon becomes apparent that the keying-in of waypoint numbers went with almost no problems. The location of practically all dwellings was recorded as a GPS waypoint. Moreover, the linking of the census questionnaire data records with corresponding waypoint records proved to be an easy exercise. The conclusion was that the GPS approach worked technically and it was decided to utilize it in the 2004 Census.
UNFPA purchased 730 Garmin eTrex GPS receivers for the census. They were chosen because of their technical capabilities and value for money.
The use of GPS technology in the 2004 Census proved to have an important additional advantage. It is possible to overlay the census results with other spatial databases, and thus determine correlations, trends and patterns otherwise impossible to recognize. In fact, the location database is now being combined with other geographic databases showing, for example, the locations and attributes of health and education facilities, roads and other infrastructure to analyze spatial relationships.
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