1. Module 8 Survey sample builder
Training in monitoring and epidemiological assessment of mass drug administration for eliminating lymphatic filariasis
Module 8 Survey sample builder

2. Learning objectives By the end of this module, you should understand:
how to use the survey sample builder to:
determine the survey design
select random clusters and children or households
the protocol for TAS

3. Overview The survey sample builder Determining the survey design
Selecting randomized clusters
Selecting randomized children or households
Protocol for TAS

4. Sample size and critical cut-off
Survey sample builder
The survey sample builder is a Microsoft Excel tool that can be used to (i) automate calculations for determining the appropriate survey design and (ii) facilitate random selection of clusters and children or households from a list of randomized numbers.
School
Census
Cluster-based
Systematic
Child
Community
Enumeration area
Household
Survey design
Random selection
Sample size and critical cut-off
Evaluation unit

5. Preparation before sample selection School-based survey
Communicate with the ministry of education to obtain a comprehensive list of all primary schools in the defined EU.
Ideally, the list of schools will be ordered according to geographical proximity rather than alphabetically. This will allow better geographical representation of the selected schools in the EU.
Obtain an average non-response rate for the schools in the EU, if available.
The non-response rate gives an estimate of the non-participant rate and should include school absenteeism, refusals and inability to collect sufficient blood for diagnostic testing.

6. Preparation before sample selection Community-based household survey
Census enumeration areas are recommended as clusters if cluster sampling is used; enumeration areas are usually the smallest areas for which census data are available.
Obtain a list of all enumeration areas in the EU.
Ideally, the enumeration areas will be listed according to geographical proximity rather than alphabetically.
Obtain enumeration area census maps.
These maps can often be obtained from the census department or bureau of statistics. A fee may be charged to obtain these maps.

7. Determining the survey design
Available for download at

8. Determining the survey design

9. Determining the survey design

10. Determining the survey design
Survey sampling method determined by data entered into programme

11. Selecting randomized clusters and children or households
Once the appropriate survey design has been determined, the survey sample builder facilitates selection of clusters and children or households by generating a list of randomized numbers.
School
Census
Cluster-based
Systematic
Child
Community
Enumeration area
Household
Survey design
Random selection
Sample size and critical cut-off
Evaluation unit

12. Selecting randomized clusters
Cluster sampling requires a minimum of 30 schools or enumeration areas in which children are selected.
Obtain a comprehensive list of all primary sampling units (i.e. schools, enumeration areas) in the evaluation unit.
Number them, preferably in order of geographical proximity as opposed to alphabetical order to achieve better geographical distribution of the evaluation unit.
Once all sampling units have been assigned a number, click the “Randomize” button.
Once the survey design has been determined, a list of random numbers (e.g. 10, 23, 36, 49 …) is generated. Select the schools or enumeration areas in the list according to the random numbers (i.e. 10th, 23rd, 36th, 49th …).

13. Selecting randomized clusters
A list of random numbers can be generated to facilitate the selection of clusters to be included.
The following schools or enumeration areas have been selected for your study: 10 23 36 49 62 76 89
102 ….

14. Selecting randomized clusters
Selection of 5–10 additional clusters is recommended as a contingency plan if the sample size falls considerably short of the target after all the clusters have been surveyed.
Additional clusters should be selected from a list of all remaining clusters, excluding those that have already been chosen. The same random selection process used for the original clusters should be used.
The survey sample builder allows selection of additional clusters.

15. Selecting randomized children or households
After selection of randomized clusters in cluster sampling or after choosing systematic sampling, children (in school-based surveys) or households (in community-based surveys) are selected randomly.
The survey sample builder calculates the appropriate sampling interval.
The survey sample builder also calculates a random starting number and the sampling interval (inverse of the sampling fraction) to generate two numbered lists (A and B) to guide the actual selection of schoolchildren or households
For school-based surveys, lists A and B are used to select the children to be tested.
For community-based surveys, lists A and B are used to select the houses in the enumeration areas to be sampled.

16. Selecting randomized children or households
In this example, the team chose list A; therefore, the first, third, fourth, fifth … house on the list or map will be selected.
Every 6- and/or 7-year-old child in the house should be tested. The same list should be used throughout the survey.

17. Example 1 Net school enrolment ratio: 78% Primary vector: Culex
Population of students in target grades:
Total number of primary schools: 386
Estimated non-response rate: 15%

18. Cluster Survey of School Entrants
Example 1. Survey design
Country:
Example 1
Name of EU:
Primary Vector:
Anopheles, Culex, or Mansonia
Demographic data on EU (provided by user)
Population of students in target grade(s):
18,945
Total number of schools:
386
Avg. number of students in target grade(s) per school: 49
*Note, if any of the above information is incorrect, click on the 'Back to "Start Here"' button and then click 'edit EU information'
Cluster Survey of School Entrants
Survey Sampling Methodology (calculated by program)
Sample Size for Cluster Design
1,552
Number of Clusters1 38
Sampling Fraction (of children within the schools)1
Test all children in the target grade(s)
Sampling Interval (of children within the schools)1
N/A
Critical Cut-off (maximum # positive ICT/Brugia Rapid results allowable for country to "Pass") 18 1
Based on a 15% absentee rate

19. Example 1. Randomized cluster selection
Directions: Obtain a comprehensive list of all the primary sampling units (i.e. schools or enumeration areas) in the evaluation unit, and number them, preferably in order of geographical proximity. Once all sampling units have been assigned a number, double-check that the values listed below are correct, and click the "Randomize" button. When you have finished, you can click "Return to previous page”.
Total number of schools:
386
No. of schools (clusters) to be sampled: 38
The following schools have been selected for your study: 8 18 29 39 49 59 69 79 90
100
110 …

20. Example 1. Randomized cluster selection
School name 1
Woodridge Elementary 2
Lakeside Elementary 3
Shadow Rock Elementary 4
Austin Elementary 5
Idlewood Elementary 6
Henderson Mill Elementary 7
Stone Mill Elementary 8
Rockland Elementary 9
Sage Elementary 10
Oak Grove Elementary 11
Brockett Elementary 12
Princeton Elementary 13
Chestnut Elementary 14
Rockbridge Elementary 15
Dresden Elementary 16
Midvale Elementary 17
Columbia Elementary 18
Pine Ridge Elementary 19
Flatrock Elementary 20
Snapfinger Elementary …
The following schools have been selected for your study: 8 18 29 39 49 59 69 79 90
100
110 …

21. Example 2 Net school enrolment ratio: 68% Primary vector: Anopheles
Population of students in target grades:
Total number of enumeration areas: 284
Estimated non-response rate: 15%

22. Cluster Survey of Households
Example 2. Survey design
Country:
Example 2
Name of EU:
Primary Vector:
Anopheles, Culex or Mansonia
Demographic data on EU (provided by user)
Population of 6-7 yrs:
23,128
Total number of EAs:
284
Avg. population 6-7yrs per EA: 81
*Note, if any of the above information is incorrect, click on the 'Back to "Start Here"' button and then click 'edit EU information'
Cluster Survey of Households
Survey Sampling Methodology (calculated by program)
Sample Size for Cluster Design
1,552
Number of Clusters1 30
Sampling Fraction (of children within the EAs)1
0.75
Sampling Interval (of children within the EAs)1
1.34
Critical Cut-off (maximum # positive ICT/Brugia Rapid results allowable for country to "Pass") 18 1
Based on a 15% absentee rate

23. Example 2. Randomized selection of households
Lists corresponding to the houses selected for sampling out of all houses in the selected enumeration area
The random number used to generate these lists is:
List A
List B 1 3 2 4 5 7 6 8 9 11 10 12 13 15 14 16 … 1 2 3 4 5 6 12 11 10 9 8 7

24. Example 3 Net school enrolment ratio: 95% Primary vector: Aedes
Population of students in target grades: 2 814
Total number of primary schools: 24
Estimated non-response rate: 15%

25. Example 3. Survey design Country: Example 3 Name of EU:
Primary Vector:
Aedes
Demographic data on EU (provided by user)
Population of students in target grade(s):
2,814
Total number of Schools: 24
Avg. number of students in target grade(s) per school:
117
*Note, if any of the above information is incorrect, click on the 'Back to "Start Here"' button and then click 'edit EU information'
Systematic Sample of School Entrants
Survey Sampling Methodology (calculated by program)
Sample Size for Systematic Sample
1172
Sampling fraction (children within each school)1
0.49
Sampling interval (children within each school)1
2.04
Critical Cut-off (maximum # positive ICT/Brugia Rapid results allowable for country to "Pass") 7 1
Based on a 15% absentee rate
Will visit every school in the evaluation unit

26. Protocol for TAS Define EU Determine survey site and sampling strategy
Calculate sample size
Prepare lists
Schools (school-based survey)
Enumeration areas (community-based survey)
Test selected children
ICT (areas endemic for W. bancrofti)
Brugia RapidTM (areas endemic for Brugia spp.)
Interpret results on basis of critical cut-off

27. Exercise
Using population data from the evaluation unit(s) defined in the ‘Evaluation unit’ module:
Use the survey sample builder to define:
the appropriate survey design
the sample size needed
the number of clusters needed for the survey
the sampling fraction
the sampling interval
Use the survey sample builder to:
select clusters to be included (if necessary)
generate lists A and B (if necessary)