USING GEOSPATIAL ANALYSIS TO INFORM DECISION MAKING IN TARGETING HEALTH FACILITY- BASED PROGRAMS A GUIDANCE DOCUMENT Josh M. Colston Clara R. Burgert MEASURE Evaluation www.cpc.unc.edu/measure MEASURE Evaluation is funded by the U.S. Agency for International Development (USAID) through Cooperative Agreement GHA-A-00-08-00003-00 and is implemented by the Carolina Population Center at the University of North Carolina at Chapel Hill, in partnership with Futures Group, ICF International, John Snow, Inc., Management Sciences for Health, and Tulane University. The views expressed in this publication do not necessarily reflect the views of USAID or the United States government. June 2014 MS-14-88 ii Table of Contents List of Tables and Figures .................................................................................................................. v Acronyms ...................................................................................................................................... vi Overview ......................................................................................................................................... vii How to Use this Guidance Document ........................................................................................................... 1 Geospatial Analysis Summary ....................................................................................................................... 3 Question 1: Where Are Existing Services Currently Located? ......................................................... 3 Question 2: Where Is the Eligible Population that Does Not Have Access to the Service? ............. 3 Question 3: How Should Future Investments in Facility-Based Services Be Allocated? .................. 4 Sequence of Decisions that Are Part of a Geospatial Analysis ..................................................................... 5 Example: Access to Antenatal Care in Namibia .......................................................................................... 9 Scenario ....................................................................................................................................... 9 Question 1: Where Are Existing Services Currently Located? ........................................................ 10 Question 2: Where Is the Eligible Population that Lack Access to ANC? ....................................... 12 Data on Population Distribution and Structure ................................................................ 12 Question 3: Where Should the Government Target Future Investments in ANC Programs? ....... 13 Mapping Accessibility Ratios ...................................................................................... 13 Findings from Using Aggregated Data to Measure Accessibility Ratios ........................... 16 Mapping Theoretical Catchment Areas ............................................................................ 17 Conclusion ......................................................................................................................................... 23 Annex A: Glossary ....................................................................................................................................... 25 Annex B: Health Service Environment Data ................................................................................................ 29 a. Geographic Identifiers ................................................................................................................ 29 b. Health Facility Attributes ........................................................................................................... 30 c. Sources of Geo-referenced Health Service Data ........................................................................ 30 Annex C: Population Data ........................................................................................................................... 33 a. Data on Population Distribution and Structure ......................................................................... 33 i. Aggregated Population Data ...................................................................................... 33 ii. Raster Population Layers ...................................................................................... 34 iii. Gazetteer Point Data ...................................................................................... 35 b. Data on Service Utilization ......................................................................................................... 35 Annex D: Geospatial Methods for Deciding Where to Allocate Resources ................................................ 39 a. Administrative Unit-Level or Aggregated Analysis ..................................................................... 39 iii i. Accessibility Ratios ...................................................................................... 39 b. Straight-Line Distance Methods ................................................................................................ 41 c. Define Catchment Areas ............................................................................................................ 43 i. Thiessen Polygons ...................................................................................... 44 ii. Buffers ...................................................................................... 46 iii. Network Analysis ...................................................................................... 48 iv. Kernel Density Estimation ...................................................................................... 50 Annex E: General Geospatial Methods for Converting between Different Types of Data ......................... 53 a. Spatial Join ................................................................................................................................. 53 b. Calculate a New Raster for the Eligible Population ................................................................... 54 c. Zonal Statistics ............................................................................................................................ 55 d. Calculating Polygon Centroids ................................................................................................... 56 References ......................................................................................................................................... 57 iv List of Tables and Figures Figure 1: Determining the appropriate geospatial method based on the available geographic identifiers. ................................................................................................................................... 7 Figure 2: Determining the appropriate catchment area analysis based on the available data. ............... 8 Figure 3: Health facility locations and region boundaries in Namibia. .................................................... 10 Table 1: Regional Level Antenatal Care Coverage in Namibia ............................................................... 11 Figures 4: ANC accessibility ratios (a) and ANC coverage gaps are combined to show ANC access and cover (c). ................................................................................................................................... 15 Figure 5: Route taken through the flowchart in this example. ............................................................... 16 Figure 6: Steps for creating Thiessen polygons and buffers for health facilities offering ANC in Khomas region. ....................................................................................................................................... 19 Figure 7: Route taken through the flowchart in this example. ............................................................... 20 Figure 8: Areas for potential targeting of investments in ANC. .............................................................. 21 Figure 9: Schematic of the main steps taken in the illustrative Namibia example. ................................ 22 Table 2: Administrative Hierarchy of Namibia ....................................................................................... 29 Table 3: Example of Identifiers in a Table ................................................................................................... 29 Table 4: Example of Number of Facilities by Administrative Unit .......................................................... 30 Figure 10: Illustrative example of Spider-diagrams representing the straight-line distances from population settlements to health facilities. .............................................................................. 41 Figure 11: Illustrative example of Thiessen polygons created based on a set of points representing health facilities. ......................................................................................................................... 44 Figure 12: Illustrative example of a set of points with 30km buffers. ....................................................... 46 Figure 13: Example of service area polygons defined by network distance. ............................................ 49 Figure 14: Illustrative example of a KDE raster layer generated based on health facility locations. ........ 51 v Acronyms AIS AIDS Indicator Survey ANC antenatal care DHS Demographic and Health Surveys GIS geographic information system GPS global positioning system GPW Gridded Population of the World GRUMP Global Rural Urban Mapping Project