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A Powerful Partnership: GIS and Sampling

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Presentation from the May 2015 webinar on GIS and sampling.

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A Powerful Partnership: GIS and Sampling

  1. 1. John Spencer Peter Lance Aiko Hattori MEASURE Evaluation University of North Carolina at Chapel Hill May 2015 Webinar Apowerful partnership: GIS and Sampling
  2. 2. MEASURE Evaluation Publication: GIS and Sampling Available at MEASURE Evaluation web site. measureevaluation.org/publications
  3. 3. Household surveys are an important source of information, but they are expensive.
  4. 4. Increasing emphasis on narrowly targeted sub-populations of interest
  5. 5. How does one find these populations of interest?
  6. 6. Geographic Information Systems (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present data using a geographic context. Adapted from wikipedia
  7. 7. GIS makes it possible to link data using a common geography. This leads to better understanding of the context of data.
  8. 8. GIS slices the world into layers.
  9. 9. GIS can be a cost effective, practical solution that can result in better surveys.
  10. 10. A modest investment in GIS can make the survey process more efficient and effective.
  11. 11. How can GIS help with sampling?
  12. 12. GIS is a very efficient way to find a population of interest in a larger group of people…
  13. 13. Provided there is a spatial pattern to the population.
  14. 14. The key is whether GIS can effectively identify the spatial pattern for predictive purposes
  15. 15. A concrete example…
  16. 16. Sampling: The process of selecting samples that allow us to learn something about populations
  17. 17. Income
  18. 18. Income Health Spending
  19. 19. Income Health Spending ?
  20. 20. Income Health Spending ? ?
  21. 21. Income Health Spending ?? ?
  22. 22. Income Health Spending ?? ? ?
  23. 23. Income Health Spending ?? ? ? ?
  24. 24. Income Health Spending ?? ? ? ? ?
  25. 25. Income Health Spending ?? ? ? ?? ?
  26. 26. Income Health Spending ?? ? ? ?? ? ?
  27. 27. Income Health Spending ?? ? ? ?? ? ??
  28. 28. Income Health Spending ?? ? ? ?? ?? ??
  29. 29. Income Health Spending
  30. 30. Income Health Spending ?
  31. 31. Income Health Spending ? ?
  32. 32. Income Health Spending ? ? ?
  33. 33. Income Health Spending ? ? ? ?
  34. 34. Income Health Spending ? ? ? ? ?
  35. 35. Income Health Spending ? ? ? ? ? ?
  36. 36. Income Health Spending
  37. 37. Income Health Spending
  38. 38. Income Health Spending
  39. 39. Income Health Spending
  40. 40. Income Health Spending
  41. 41. Probability Sampling 1. Each member of the population is in the “list” from which we will select 2. We know each member of the population’s probability of selection from the list
  42. 42. So how in practice do we select in accordance with probability sampling???? We usually do so from a list of the population called a sampling frame. That list must contain all members of the population (sampling units) to satisfy probability sampling
  43. 43. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian 2 Andre Jones 302 Lyon Lane African American 3 Michelle M. Lee 101 Jay Street Asian American 4 Dan T. Waters 402 Smith Street Caucasian 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  44. 44. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American 3 Michelle M. Lee 101 Jay Street Asian American 4 Dan T. Waters 402 Smith Street Caucasian 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  45. 45. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American 4 Dan T. Waters 402 Smith Street Caucasian 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  46. 46. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  47. 47. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  48. 48. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  49. 49. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  50. 50. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  51. 51. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  52. 52. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  53. 53. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  54. 54. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  55. 55. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No 12 Gary Park 55 Park Avenue Asian American … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  56. 56. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No 12 Gary Park 55 Park Avenue Asian American No … … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  57. 57. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No 12 Gary Park 55 Park Avenue Asian American No … … … … … 10548 Peter R. Martinez 404 Main Street Latino No 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  58. 58. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No 12 Gary Park 55 Park Avenue Asian American No … … … … … 10548 Peter R. Martinez 404 Main Street Latino No 10549 Faith B. Rogers 201 Cedar Street African American No 10550 Will Billings 402 Buford Place Caucasian
  59. 59. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian No 2 Andre Jones 302 Lyon Lane African American No 3 Michelle M. Lee 101 Jay Street Asian American No 4 Dan T. Waters 402 Smith Street Caucasian No 5 Molly McGuire 111 Main Street Caucasian Yes 6 Ron S. Swanson 0 Opsec Ave Caucasian No 7 Lisa Levine 3 Phillips Ave Caucasian No 8 Andrea Rice 14 Main Street African American No 9 Hunter Lewis 29 9th Avenue Caucasian No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No 12 Gary Park 55 Park Avenue Asian American No … … … … … 10548 Peter R. Martinez 404 Main Street Latino No 10549 Faith B. Rogers 201 Cedar Street African American No 10550 Will Billings 402 Buford Place Caucasian Yes
  60. 60. No Name Address Race Selected? 1 Burt T. Macklin 100 April Street Caucasian 2 Andre Jones 302 Lyon Lane African American 3 Michelle M. Lee 101 Jay Street Asian American 4 Dan T. Waters 402 Smith Street Caucasian 5 Molly McGuire 111 Main Street Caucasian 6 Ron S. Swanson 0 Opsec Ave Caucasian 7 Lisa Levine 3 Phillips Ave Caucasian 8 Andrea Rice 14 Main Street African American 9 Hunter Lewis 29 9th Avenue Caucasian 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American 12 Gary Park 55 Park Avenue Asian American … … … … 10548 Peter R. Martinez 404 Main Street Latino 10549 Faith B. Rogers 201 Cedar Street African American 10550 Will Billings 402 Buford Place Caucasian
  61. 61. No Name Address Race Selected? 2 Andre Jones 302 Lyon Lane African American 8 Andrea Rice 14 Main Street African American 10 Jennifer Lownes 14c Avenue A African American 11 Anna A. Anderson 148d Avenue A African American … … … … 10549 Faith B. Rogers 201 Cedar Street African American
  62. 62. No Name Address Race Selected? 2 Andre Jones 302 Lyon Lane African American No 8 Andrea Rice 14 Main Street African American No 10 Jennifer Lownes 14c Avenue A African American Yes 11 Anna A. Anderson 148d Avenue A African American No … … … … 10549 Faith B. Rogers 201 Cedar Street African American Yes
  63. 63. >>>>>Stratification<<<<<
  64. 64. Multistage Sampling
  65. 65. DHS
  66. 66. Census Clusters Households Women within Households
  67. 67. What We Have Learned • Representative estimates typically require probability sampling • Probability sampling is in practice most commonly performed with lists from the entire population called a sampling frame • Sampling can be stratified by dividing the frame into mutually exclusive and exhaustive separate frames for different subpopulations • You can still form a representative estimate for a subpopulation even if the selected units from it are scattered across frames for different strata • In practice sampling is usually multistage
  68. 68. Dengue Fever
  69. 69. The Plan
  70. 70. The Sample Size Objective 112 Clusters
  71. 71. Now, we know an important survey prior: History suggests that we will find dengue cases in only around 4.9 percent of clusters.
  72. 72. Let’s Talk Costs $200: The cost to monitor each selected study cluster $2000: The fieldwork cost per cluster with a dengue outbreak This means an expected cost per cluster of $200+.049 x $2000 ≈$298
  73. 73. Uh Oh At that price, we can afford to select only $300,000/$298≈1006 clusters From these we would expect only 1006 X .049≈49 clusters to have a dengue outbreak.
  74. 74. Even worse: We are 112-49=63 clusters short!!!
  75. 75. My name is Aedes Aegypti.
  76. 76. I really like to bite.
  77. 77. But I’m also kinda lazy
  78. 78. But can we exploit this with GIS?
  79. 79. Sampling Units
  80. 80. Sampling Units Risk Factor
  81. 81. Sampling Units Risk Factor Risk Factor
  82. 82. Sampling Units Risk Factor Risk Factor Risk Factor
  83. 83. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  84. 84. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  85. 85. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  86. 86. Uh Oh
  87. 87. (Yeah…we’re kind of picky)
  88. 88. 59 Feet
  89. 89. 59 Feet 59 Feet
  90. 90. 46 Feet 59 Feet 59 Feet
  91. 91. 46 Feet 59 Feet 33 Feet 59 Feet
  92. 92. 46 Feet 59 Feet 33 Feet 33 Feet 59 Feet
  93. 93. 46 Feet 59 Feet 33 Feet 33 Feet 46 Feet 59 Feet
  94. 94. 46 Feet 59 Feet 33 Feet 33 Feet 30 Feet 46 Feet 59 Feet
  95. 95. 46 Feet 59 Feet 33 Feet 33 Feet 30 Feet 46 Feet 59 Feet 39 Feet
  96. 96. 46 Feet 59 Feet 33 Feet 33 Feet 30 Feet 46 Feet 59 Feet 39 Feet 52 Feet
  97. 97. 46 Feet 59 Feet 33 Feet 33 Feet 30 Feet 46 Feet 59 Feet 39 Feet 52 Feet 49 Feet
  98. 98. 46 Feet 59 Feet 33 Feet 33 Feet 30 Feet 46 Feet 59 Feet 39 Feet 52 Feet 49 Feet 82 Feet
  99. 99. 33 Feet 39 Feet 59 Feet 52 Feet 49 Feet 33 Feet 46 Feet
  100. 100. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  101. 101. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  102. 102. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  103. 103. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  104. 104. Sampling Units Risk Factor Risk Factor Risk Factor Risk Factor
  105. 105. Two Strata of Clusters • Low Risk: 95% of clusters have a Low Risk of Dengue Outbreak (2% risk of outbreak during study) • High Risk: 5% of clusters have a High Risk of Dengue Outbreak (60% risk of outbreak during study) Note that this is consistent with 4.9% overall risk across clusters: .95 X .02 + .05 X .6 ≈ .049
  106. 106. High Outbreak Risk Low Outbreak Risk
  107. 107. High Outbreak Risk Low Outbreak Risk
  108. 108. High Outbreak Risk Low Outbreak Risk
  109. 109. High Outbreak Risk Low Outbreak Risk
  110. 110. The Power of Sampling and GIS One Possible $300,000 Scheme: Sample 180 High Risk clusters with expected yield of 108 with dengue outbreaks AND Sample 200 Low Risk clusters with a expected yield of 4 dengue outbreaks
  111. 111. The Payoff • Without Stratification: We expect to observe 49 clusters with dengue outbreaks • With Stratification: We expect to observe 112 clusters with dengue outbreaks
  112. 112. Let’s consider a counterfactual: how much survey budget we would need to obtain 112 dengue clusters without stratification into high and low risk clusters? 112 .049 𝑋 $298 = $681,142.86
  113. 113. Let’s consider a counterfactual: how much survey budget we would need to obtain 112 dengue clusters without stratification into high and low risk clusters? 112 .049 𝑋 $298 = $681,142.86
  114. 114. Let’s consider a counterfactual: how much survey budget we would need to obtain 112 dengue clusters without stratification into high and low risk clusters? 112 .049 𝑋 $298 = $681,142.86
  115. 115. Let’s consider a counterfactual: how much survey budget we would need to obtain 112 dengue clusters without stratification into high and low risk clusters? 112 .049 𝑋 $298 = $681,142.86
  116. 116. Let’s consider a counterfactual: how much survey budget we would need to obtain 112 dengue clusters without stratification into high and low risk clusters? 112 .049 𝑋 $298 = $681,142.86
  117. 117. Fieldwork Costs to Get 112 Clusters with Outbreak With GIS Without GIS $ 300,000.00 $681,142.86
  118. 118. A GIS Isn’t Free… It Costs Something to Build One
  119. 119. Difference in survey fieldwork costs Without GIS: $681,142.86 With GIS: $300,000.00 $381,142.86
  120. 120. $381,142.85!!!!!
  121. 121. $381,142.85!!!!!
  122. 122. “Big Ideas” We were trying to sample from a subpopulation
  123. 123. “Big Ideas” That subpopulation had a predictable spatial pattern to its distribution
  124. 124. “Big Ideas” We used a GIS as a framework to predict where the subpopulation was likely to be
  125. 125. “Big Ideas” We then stratified the frame for the study area into high and low “risk” sampling units
  126. 126. The Point This gave us the ability to sample far more from the subpopulation for a given survey cost.
  127. 127. The Point As long as it is not too expensive to build, the GIS can reduce the costs of obtaining a sample of a given size from the subpopulation.
  128. 128. Principles GIS and Sampling Full list in publication.
  129. 129. West Nile Virus
  130. 130. Have a clear protocol for GIS construction
  131. 131. •Automate as much as possible
  132. 132. •For instance automated rooftop signature calculation
  133. 133. Yet be aware that the world is full of surprises
  134. 134. Groundtruth
  135. 135. Assumptions will have consequences
  136. 136. The road ahead…
  137. 137. There is more spatial data than ever before and GIS software is easier to use than it has ever been.
  138. 138. There is also more data in general available than ever before.
  139. 139. GIS can bring all of that data together to create cheaper, better surveys.
  140. 140. MEASURE Evaluation Publication: GIS and Sampling Available at MEASURE Evaluation web site. measureevaluation.org/publications
  141. 141. MEASURE Evaluation is funded by the U.S. Agency for International Development (USAID) under terms of Cooperative Agreement AID-OAA-L-14-00004 and implemented by the Carolina Population Center, 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 presentation do not necessarily reflect the views of USAID or the United States government. www.measureevaluation.org

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