Presentation from the May 2015 webinar on GIS and sampling.

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. MEASURE Evaluation Publication:
GIS and Sampling
Available at MEASURE
Evaluation web site.
measureevaluation.org/publications

3. Household surveys are an
important source of
information,
but they are expensive.

4. Increasing emphasis on narrowly
targeted sub-populations of interest

5. How does one find these
populations of interest?

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. GIS makes it possible to link data using a common geography.
This leads to better understanding of the context of data.

8. GIS slices the world
into layers.

9. GIS can be a cost
effective, practical
solution that can result in
better surveys.

10. A modest
investment
in GIS can
make the
survey
process
more
efficient and
effective.

11. How can GIS help with sampling?

12. GIS is a very efficient way to find a
population of interest in a larger group of
people…

13. Provided there is a spatial pattern to the
population.

14. The key is whether GIS can effectively identify the
spatial pattern for predictive purposes

15. A concrete example…

16. Sampling:
The process of selecting samples
that allow us to learn something
about populations

18. Income

19. Income
Health Spending

20. Income
Health Spending
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21. Income
Health Spending
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22. Income
Health Spending
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23. Income
Health Spending
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24. Income
Health Spending
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25. Income
Health Spending
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26. Income
Health Spending
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27. Income
Health Spending
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28. Income
Health Spending
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29. Income
Health Spending
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? ?? ??
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30. Income
Health Spending

31. Income
Health Spending
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32. Income
Health Spending
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33. Income
Health Spending
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34. Income
Health Spending
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35. Income
Health Spending
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36. Income
Health Spending
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37. Income
Health Spending

38. Income
Health Spending

39. Income
Health Spending

40. Income
Health Spending

41. Income
Health Spending

44. 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

45. 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

46. 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

47. 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

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
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

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
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

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
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

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
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

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
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

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
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

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
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

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
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

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
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

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
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

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
… … … … …
10548 Peter R. Martinez 404 Main Street Latino
10549 Faith B. Rogers 201 Cedar Street African American
10550 Will Billings 402 Buford Place Caucasian

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
10549 Faith B. Rogers 201 Cedar Street African American
10550 Will Billings 402 Buford Place Caucasian

60. 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

61. 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

62. 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

63. 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

64. 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

65. 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

66. >>>>>Stratification<<<<<

82. Multistage Sampling

83. DHS

84. Census Clusters
Households
Women within Households

85. 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

86. Dengue
Fever

88. The Plan

89. The Sample Size Objective
112 Clusters

91. Now, we know an important survey prior:
History suggests that we will find dengue
cases in only around 4.9 percent of
clusters.

92. 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

93. 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.

94. Even worse:
We are 112-49=63 clusters short!!!

109. My name is Aedes Aegypti.

110. I really like to bite.

111. But I’m also kinda lazy

116. But can we exploit this with GIS?

118. Sampling Units

119. Sampling Units
Risk Factor

120. Sampling Units
Risk Factor
Risk Factor

121. Sampling Units
Risk Factor
Risk Factor
Risk Factor

122. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

123. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

126. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

134. Uh Oh

138. (Yeah…we’re kind of picky)

146. 59 Feet

147. 59 Feet
59 Feet

148. 46 Feet
59 Feet
59 Feet

149. 46 Feet
59 Feet
33 Feet
59 Feet

150. 46 Feet
59 Feet
33 Feet
33 Feet
59 Feet

151. 46 Feet
59 Feet
33 Feet
33 Feet
46 Feet
59 Feet

152. 46 Feet
59 Feet
33 Feet
33 Feet
30 Feet
46 Feet
59 Feet

153. 46 Feet
59 Feet
33 Feet
33 Feet
30 Feet
46 Feet
59 Feet 39 Feet

154. 46 Feet
59 Feet
33 Feet
33 Feet
30 Feet
46 Feet
59 Feet 39 Feet
52 Feet

155. 46 Feet
59 Feet
33 Feet
33 Feet
30 Feet
46 Feet
59 Feet 39 Feet
52 Feet
49 Feet

156. 46 Feet
59 Feet
33 Feet
33 Feet
30 Feet
46 Feet
59 Feet 39 Feet
52 Feet
49 Feet
82 Feet

157. 33 Feet
39 Feet
59 Feet
52 Feet
49 Feet
33 Feet
46 Feet

162. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

163. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

169. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

170. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

171. Sampling Units
Risk Factor
Risk Factor
Risk Factor
Risk Factor

174. 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

175. High Outbreak
Risk
Low Outbreak
Risk

176. High Outbreak
Risk
Low Outbreak
Risk

177. High Outbreak
Risk
Low Outbreak
Risk

178. High Outbreak
Risk
Low Outbreak
Risk

179. 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

180. The Payoff
• Without Stratification: We expect to
observe 49 clusters with dengue outbreaks
• With Stratification: We expect to observe
112 clusters with dengue outbreaks

181. 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

182. 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

183. 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

184. 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

185. 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

186. Fieldwork Costs to Get 112 Clusters with
Outbreak
With GIS Without GIS
$ 300,000.00 $681,142.86

188. A GIS Isn’t Free…
It Costs Something to Build One

189. Difference in survey fieldwork
costs
Without GIS: $681,142.86
With GIS: $300,000.00
$381,142.86

196. $381,142.85!!!!!

198. $381,142.85!!!!!

199. “Big Ideas”
We were trying to sample from a
subpopulation

200. “Big Ideas”
That subpopulation had a predictable spatial
pattern to its distribution

201. “Big Ideas”
We used a GIS as a framework to predict
where the subpopulation was likely to be

202. “Big Ideas”
We then stratified the frame for the study
area into high and low “risk” sampling units

203. The Point
This gave us the ability to sample far
more from the subpopulation for a given
survey cost.

204. 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.

205. Principles
GIS and Sampling
Full list in publication.

206. West Nile Virus

210. Have a clear protocol for GIS construction

211. •Automate as much as possible

212. •For instance
automated
rooftop
signature
calculation

213. Yet be aware that the world is full of surprises

214. Groundtruth

216. Assumptions will
have consequences

217. The road ahead…

218. There is more spatial data than ever before and GIS
software is easier to use than it has ever been.

219. There is also more data in general available than
ever before.

220. GIS can bring all of that data together to create
cheaper, better surveys.

221. MEASURE Evaluation Publication:
GIS and Sampling
Available at MEASURE
Evaluation web site.
measureevaluation.org/publications

222. 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