Demarcation of census enumeration areas for the 2016 population and housing census in Lesotho

Transcription

1 Demarcation of census enumeration areas for the 2016 population and housing census in Lesotho by Hennie Loots, GeoSpace International Abstract A national population and housing census refers to the collection of basic socio-demographic and housing information for every household and individual within the borders of a country. In preparation for a population and housing census the entire country is divided into small areas of land each one big enough to be handled by one interviewer during the time of the census. This is referred to as pre-enumeration census mapping or demarcation and the resultant demarcated areas are called Enumeration Areas (EAs). GeoSpace International is arguably the leading geospatial service provider in the pre-enumeration census mapping in Africa. The company has provided products and services (methodology development, training, technical support and project management) to more than ten countries in Africa during the 2000 and current (2010) round of censuses. This paper firstly gives an overview of the main lessons learnt from the 2006 pre-enumeration census mapping project in Lesotho. The 2016 pre-enumeration census mapping in Lesotho is then discussed with specific focus on how the shortcomings of 2006 were addressed. This project, currently still in progress, is a valuable case study where the latest technology (software and base map imagery) has been successfully combined in an exciting total solution that is likely to be utilised wider in Africa during the current and subsequent rounds of censuses. The most exciting new technology being used in this project is Smart Client for Census a specially adapted version of Hexagon s Geomedia Smart Client GIS client-server technology. Smart Client provides basic GIS functionality (data capturing, queries and reporting) in a client-server environment. The software can be used online as well as offline a key requirement in most remote areas in Africa. Smart Client for Census acts as the backbone of the entire project. Different users, office and field, access the system through standard internet access protocols (username and password) to execute tasks allocated to them based on the different workflows of the project. A specific user can only do the tasks allocated to him/her within the geographical areas assigned to him/her. As such Smart Client enables elegant management and monitoring of the project whilst facilitating workflow-driven pre-determined tasks. The paper gives an overview of the methodology, current status as well as the main benefits of the Smart Client census mapping solution. Keywords population and housing census, census mapping, statistics, GIS, ASSD, national statistical office, Hexagon, GeoSpace International, Smart Client Introduction A population census is the total process of collecting, compiling, evaluating, analysing and publishing or otherwise disseminating demographic, economic and social data pertaining, at a specified time, to all persons in a country or in a well-delimited part of a country [1]. A census is the most important and costly statistical data collection exercise conducted by a national statistical office (NSO). It is usually conducted every ten years and the results provide a detailed, small geographic area, snapshot of the demographic, socio-demographic and housing status of a country. It also provides the basis (master sample frame) for a wide range of sample surveys. In preparation for a population and housing census the entire country is divided into small areas of land each one big enough to be handled by one interviewer during the time of the census. This is referred to as preenumeration census mapping or demarcation and the resultant demarcated areas are called Enumeration Areas (EAs). In some countries such as Sweden and Austria door-to-door canvassing to collect census data has been replaced by a registered-based census. However in some parts of the world such as Africa civil registration and housing registers are not complete and current hence a conventional census is an important source of information and will remain relevant, if not critical, for many years to come. In order to conduct a door-to-door census the census cartographer needs to provide the census enumeration team with a set of unique maps covering the entire country that accurately defines the boundaries within which each interviewer (enumerator) has to work during the enumeration phase of the census. Furthermore the user community nowadays demands statistics to be provided within a spatial context hence desktop and server-based GIS solutions have become an important part of census data products and dissemination. 74

2 Lesotho: overview of the 2006 census mapping project and lessons learnt Overview The Lesotho Bureau of Statistics (BOS) is the government agency tasked with official statistics in Lesotho. At the time Lesotho was one of only a few African countries to implement GIS/GPS and remote sensing technology for the pre-enumeration cartographic work. A first for BOS was the use of 2,5 m SPOTMaps satellite imagery (from SPOT 5 which was launched in 2002) as the base map for a census at national level. Over and above the satellite imagery base map all available spatial data from official government and parastatal sources was obtained. This data was used to populate the 2006 census EA database. Once this was done the production work of the project commenced. This was done in three stages: Office work phase 1: Preparatory office work Fieldwork Office work phase 2: Data capturing and EA/SA map creation and printing Preparatory office work involved the preparation of fieldwork maps and materials to be used during fieldwork. A0/A1-sized maps were prepared by superimposing the vector data such as administrative boundaries, place names, roads, hydrology, power lines and points of interest (POIs) on top of the satellite imagery. During fieldwork the data and maps prepared in the office were firstly verified and updated and new data, or data that was not previously captured, was captured. This was done through annotation on the map and filling out of specially designed fieldwork forms. GPS was used to capture POI data. EA boundaries were annotated on the map. During the third stage, office work phase 2, the data collected in the field was firstly captured. Once completed EA and Supervisor Area (SA) maps were created and printed. In the majority of cases these maps were A3-sized (colour). All the maps for the 2006 census enumeration were prepared using GIS - at the time Lesotho was one of only a few countries on the continent that managed to achieve this. Lessons learnt from 2006 areas identified for improvement in 2016 A census is a costly exercise. Hence Lesotho BOS are constantly researching alternative technologies that can lower costs whilst improving efficiency and quality. Although the satellite imagery base map worked well in most cases the need was expressed for a higher resolution base map for The main reason being difficulties experienced in the identification of cattle posts in remote rural areas. In some cases enumerators also complained that it was difficult to identify EA boundaries on the ground due to the lack of detail. Arguably the biggest shortcoming of the 2006 project was that the different phases of the project were managed in isolation of the rest and even though standard project management tools were used it was effectively done manually. This made project management (scheduling of work, progress tracking and reporting) a huge challenge. Hence the need was expressed to implement an integrated census mapping software solution for In 2006 the lack of a client-server environment where all users accesses the same database resulted in management problems, duplication of effort and ultimately had a negative impact on data quality. At the time no GIS software solution existed that could address this problem. The three stages of the project operated to a large extent in isolation of each other. It was difficult to schedule work and track progress. This resulted in loss of time and money due to less than optimal scheduling of work and certain cases, duplication of work (where the same area was visited twice). The data collected in the field (annotation of spatial data as well as attribute data captured on forms) had to be digitised in the office resulting in additional work as well as the usual errors associated with digitising and manual data entry. Even though the 2006 methodology and training materials were fairly advanced (at the time) it was difficult to ensure consistency in the interpretation and execution of the methodology. This again resulted in variances in data quality that ultimately compromised the final output. Hence there was a need to have a software solution that more closely guides and regulates users through the detailed steps of the methodology/workflows. Desktop GIS was used for the GIS work in Desktop GIS has much more functionality than the minimum required to do the basic production work in a census mapping project. This implies the need for advanced users with a relatively high skill level. It also implies more intensive training. An easier to use application that has all 75

3 the required functionality would lower the level of complexity associated with the implementation of the methodology whilst improving data consistency and quality. Since Lesotho is a mountainous country with extremely remote areas the mobile networks do not cover the entire country. Since fieldwork covers the entire country an important requirement of a client-server mapping solution is off-line capability. The 2016 project improvements over 2006 The base map for 2016 is 50 cm orthophotos prepared digital aerial photography. This is currently regarded as the best possible base map for census mapping. This, higher resolution imagery, addresses the problem to identify certain features on the ground that was identified as a problem in 2006 (e.g. cattle posts). The more detailed superior base map also facilitates much more accurate and clear EA boundary delineation than was previously the case. Smart Client for Census was introduced to address the rest of the lessons learnt from 2006 as discussed earlier in this paper. Smart Client for Census is discussed next followed by the roles and workflows used for the 2016 Lesotho census. Smart Client for Census Smart Client for Census is a client-server GIS software solution based on Hexagon Geospatial s GeoMedia Smart Client product. It is a java-based rich client solution for delivering sophisticated geospatial workflows. Traditional geographic information systems (GIS) are suited for census mapping but it is relatively complex to use and hence require skilled and knowledgeable users. On the other extreme of the software spectrum traditional WEB GIS again lack the functionality required for census mapping. GeoMedia Smart Client delivers a geospatial platform engineered to support large numbers of users who do not require or are unable to operate full desktop GIS products, but whose workflows need advanced geospatial functionality that cannot be supported by web-mapping tools. The positioning of Smart Client in relation to Desktop GIS and WEB GIS can be depicted as follows: Fig. 1: Smart Client positioning vs. desktop GIS and Web GIS. Smart Client does not replace desktop or web solutions, but it fills the gap that exists for delivering high-end technical geospatial capabilities to large groups of users that may not necessarily have the technical skills to use desktop GIS and do not require all the high-end functionality associated with desktop GIS. Smart Client s geospatial capabilities include high-end functions such as vector data capture and editing (including the use of snaps, construction aids, and dimensioning), redlining, analysis, and large-format true-scale plotting [2, 3]. A pre-enumeration census-mapping project typically involves large numbers of GIS operators (office) and field mappers that use GPS and/or mobile mapping applications to verify/edit and capture spatial and attribute data relevant to census mapping. If one analyses the GIS capability required to execute the tasks related to census mapping 90%+ falls within the Smart Client sphere as shown in Fig 1. The remaining (less than) 10% of tasks require desktop GIS. Hence it was decided to develop and configure a special version of the software dedicated to the unique needs of NSOs in Africa. 76

4 The key features of the software are listed below. Key features and how it addresses the challenges in census cartography (in Lesotho and elsewhere) Costs: Censuses are by far the most costly statistical data collection project in a country. There is constant pressure on NSOs to improve efficiency whilst cutting the costs associated with censuses. Traditional desktop GIS software in combination with mobile GIS software is the current standard in pre-enumeration census mapping. Since the costs associated with desktop and mobile GIS are determined by the numbers of users/licenses it is usually significant especially in countries where large numbers of temporary GIS operators and fieldworkers are deployed to do the work. Smart Client implies one license only with unlimited users this result in a significant cost-saving. Although it does not have all the functionality of a high-end desktop and mobile GIS, it has all the GIS functionality required to do pre-enumeration census mapping and more. Raster and vector data is not calculated/processed on the server side but on the client side. This enables fairly sophisticated GIS functionality including vector data capturing, attributing, redlining, measuring and querying on the client side. Smart Client therefore eliminates the need for numerous sophisticated and costly desktop and mobile GIS licenses. Only a few desktop licenses will still be required to do the more sophisticated GIS work that cannot be done by Smart Client [4]. GIS infrastructure: Smart Client implies fewer desktop GIS licenses but it does not imply the replacement of the entire current GIS infrastructure that may exist at an NSO. Since it access any established spatial database server such as Oracle Spatial or SQL server it can be used together with any desktop software e.g. GeoMedia or ArcGIS. This is a huge advantage to NSOs where there might already be an established GIS infrastructure and expertise on a particular platform. The status quo can either be retained with the addition of Smart Client to provide the increased software capacity required for the large temporary census workforce or some of the desktop GIS licenses that are usually no longer required can be replaced by Smart Client for Census [4]. Effective implementation of census workflows into the GIS environment: Although desktop and mobile GIS software has all the functionality to do census mapping the respective software s (desktop GIS in particular) have limitations when it comes to the handling and managing project-specific workflows. This is a huge challenge because it implies the use of a range of (usually unrelated) tools to establish and manage workflows. This leads to problems such as variances in the interpretation of the methodology by different users and data integration issues that emerge as a direct result of using a set of disparate tools. Ultimately it introduces unnecessary complexity which has a negative impact on data quality whilst increasing the overall risks associated with the project. At Smart Client s core is a highly configurable rules and powerful workflow engine. This is a key attribute of the software. This enables the GIS Manager to implement census-mapping workflows and feature-level access control that is managed by a single fully integrated system where all the parties, each with associated roles, access the same database(s) through a single web server. Each user (role) has a specific set of tasks relevant to his/her role. Furthermore access to the system is through standard internet/intranet security protocols involving a username and password. The access control system allows a supervisor to allocate a specific unit of work, referred to as a production unit (PU), to a particular user. Only the assigned user can do the work in the PU allocated to him/her and he/she can only execute the tasks relevant to his/her role at that particular part of the overall workflow. This eliminates duplication of efforts since it is impossible for two persons/teams to work on/in the same PU at the same time and it is also impossible for a user to do anything other than the tasks related to his/her role with regards to the allocated PU at that particular step in the overall workflow. Once the tasks for a particular PU are completed it is submitted and the Supervisor receives a notification to that effect. This then triggers a set of quality control/quality assurance (QC/QA) steps after which the work is either accepted or rejected and sent back for correction [4]. Project management: A census-mapping project is often a huge undertaking with a large workforce ranging from about 50 to more than a 1000 persons, depending on the size of the country, the methodology and the project timeframe. Project management is therefore a huge challenge. Smart Client enables the GIS Manager to manage the entire census mapping project using a single tool. Since work allocation and task execution, as described in the previous paragraph, happens on the same system the GIS Manager knows exactly who is doing what at any particular moment in time and also, importantly, the exact overall status/progress of each phase of the project. And since Smart Client has a strong spatial component work scheduling and progress tracking can be done using a combination of maps and tables/lists. This key attribute of Smart Client effectively manages, if not eliminates, most of the inefficiencies common to census mapping projects. This includes: less than optimal scheduling of fieldwork that requires field teams to drive unnecessary distances between PUs; duplication of effort where the same PU is allocated to two teams or operators; obtaining of status reports from the field and office and compiling of progress reports. 77

5 A key attribute of Smart Client is ability to detect a problem swiftly long before it turns into a major crisis [4]. Data quality: Due to the fact that numerous persons are usually working simultaneously on a censusmapping project it is a huge training and management challenge to ensure consistency in the interpretation and execution of the methodology. Smart Client vastly improves the consistency of work, hence ultimately the overall quality of the data collected/processed, by the respective parties in the workflow. Every user/role has a (sub-) workflow with specific tasks configured in the software as required by the project. The user can only execute the tasks associated with that particular (part of the) workflow nothing else. The software literally guides the user through the steps. Only the software functionality required for the execution of that particular workflow is available to the user. This ensures that all users execute the tasks in the same way ensuring consistency in the execution of the overall methodology and ultimately ensuring overall data quality and consistency [4]. Training: Since a specific user has only access to the software functionality required to execute the tasks for that particular part of the workflow it is not a key requirement to have huge GIS skills and knowledge to do the work. This is a huge advantage in Africa where GIS skills are relatively limited. Furthermore training can be much more focused and task-specific resulting in significant savings in the training budget and quicker project implementation. It is also much easier to replace staff during the project because of the lower training requirements [4]. Fieldwork in remote areas: A key requirement for census mapping software applications for fieldwork is the ability to work offline. Smart Client uses advanced caching to enables off-line use in remote areas where data access is limited or non-existent. If required, the field data capturer can work off-line for days or even weeks. It is however advisable to synchronise with the server as often as possible because progress reports are based on data obtained from the server and it will also avoid/limit potential loss of valuable data due to malfunctioning, loss or theft of field computers [4]. Roles and workflows The entire 2016 census mapping project in Lesotho is executed using Smart Client for Census. There are four roles (user groups) in the standard application as was implemented in Lesotho [5]: Office supervisor Field supervisor Fieldwork operator Office data capturer Note: the terminology above differs slightly from the original source document from BOS in order to make it more descriptive in the context of this paper. The workflow can be illustrated as follows: Fig. 2: Smart Client workflow for Lesotho census project. 78

6 The entire workflow as well as all the tasks related to each workflow is done using Smart Client. Current status The project is still in progress but some of the main phases have been completed. This includes the creation of the orthophoto base map and the populating of the Smart Client database, the configuration of the software as well as the fieldwork. Outstanding work includes the checking of the fieldwork by the office team and final EA/SA map creation and printing. Current indications are that the 2016 project is a major step forward from the previous effort and that it will be a success. Conclusion Smart Client provides an exciting solution to census mapping. It provides an excellent platform for easy scheduling of work, project tracking and reporting. The software is stable and robust. It is easy to use and requires minimal training compared to conventional desktop GIS. The flexibility to configure the software to ensure that each user knows exactly what he/she is supposed to do eliminates duplication of effort and potential differences in methodology interpretation. This improves data quality and consistency. The fact that no software installation on devices is required makes the implementation of software/application updates easy. All updates happen on the server side. Each time the user logs in any updates or changes are automatically reflected on the client side. The off-line functionality enables fieldwork to be done in remote areas. The advanced caching ensures that relatively small data packages are sent to and from the server keeping data costs and connection time to the minimum this is important from a fieldwork and budget perspective. The flexibility of the software enables it to be used for the planning and management of the subsequent phases of the census project. It can ultimately also be used as a dissemination tool. Smart Client compliments any existing GIS infrastructure rather than replacing. It does however eliminate the need for mobile GIS software and it lowers the need for high-end desktop GIS software. Since Smart Client is a java-based application it does not operate on ios and Android platforms. The Lesotho project runs on a Microsoft Windows platform both office and field. This is a drawback since numerous popular hardware devices cannot be considered for fieldwork. A further disadvantage of the Smart Client solution is that it implies that all the hardware (office and field) must be in place prior to commencement of the project. This is true of any solution but even more so in this case since it is an integrated solution that cannot function unless all the required hardware in place prior to project implementation. There were serious delays in the delivery of the field computers. It was a serious risk and nearly derailed the entire project. It is therefore important to allow sufficient time for the procurement of all the components of the solution. Furthermore NSOs are often bound to adhere to the IT rules and regulations of their respective governments. This could potentially make it difficult to have a dedicated link (though the internet) between the Smart Client server and the fieldwork computers. GeoSpace is currently working on an option to provide NSOs with a total census mapping solution that includes the Smart Client solution described in this paper integrated with an imagery base map solution consisting of Airbus Defence And Space satellite imagery (1,5 m SPOTMaps from SPOT 6 and 7 and Pleiades 50 cm imagery) complimented by GeoSpace s own digital aerial photography. The success with the Lesotho census application has proved that Smart Client is an exciting new geospatial product with applications much wider than just the census domain. References [1] United Nations Statistics Division: "Principles and Recommendations for Population and Housing Censuses Revision 2, p 7, [2] Hexagon Geospatial: GeoMedia Smart Client Wiki, 2014, [3] Hexagon Geospatial: Partner Portal, [4] GeoSpace International: Smart Client for Census, Product documentation, [5] Lesotho Bureau of Statistics: 2016 Population and Housing Census, Training Manual and Field Reference, p 57, Contact Hennie Loots, GeoSpace International, Tel , henniel@geospace.co.za 79