1. Multiple Indicator Cluster Surveys Survey Design Workshop
Sampling Overview
MICS4 Survey Design Workshop

2. MICS4 Survey Design Workshop
Introduction
MICS is multi-national survey program
Consistency and comparability between surveys is important
MICS based on national stratified multi-stage sample
Workshop session covers highlights of MICS sampling, including:
Identifying effective sampling frame and sample design
Determinants and calculation of sample size
MICS4 Survey Design Workshop

3. Importance of correct sampling procedures
Sample design will affect inferences of survey results
Coverage of frame and appropriate probability sampling are critical
Accuracy of survey results depends on both sampling and non-sampling errors
MICS4 Survey Design Workshop

4. Key concepts in proper sampling
Use accepted probability techniques at every stage of selection
Use of simple sampling methodology
Use the latest census as the sampling frame when available
Sampling in two stages
Use of clusters of moderate size
Use of an adequate sample size
MICS4 Survey Design Workshop

5. MICS4 prototype sample design
Manual presents different sampling options
All options involve two or three-stage cluster sampling
Primary sampling units (PSUs) – census enumeration areas
Listing in sample clusters or use of compact clusters
Sample households selected from listing
Option for each country depends on type of frame and availability of existing samples
MICS4 Survey Design Workshop

6. Sampling option 1 – use existing sample
Most cost-effective approach
Determine whether existing sample is appropriate
Probability sample
Known probabilities of selection at each stage
Nationally representative
Sufficient number of sample PSUs for MICS
Example – 2008 Mozambique MICS3
MICS4 Survey Design Workshop

7. Sampling option 1 – continued
Determine when listing of households in sample EAs was conducted
Listing can be used if less than 1 year old
Generally select new sample of households from listing
Possible to use selected households from other survey
Consider response burden, analytical needs for both surveys
Conduct new listing in existing sample or subsample of EAs
Availability of master sampling frame in some countries
MICS4 Survey Design Workshop

8. Sampling option 2 – standard segment design
Based on standard segments of about 500 persons or 100 households
Effective procedure when some EAs are too large for listing
Three-stage sample design
Measure of size for each EA – calculated number of segments
EAs selected systematically with PPS
Larger sample EAs with 2 or more segments subdivided
One segment selected in each EA for listing, enumeration
MICS4 Survey Design Workshop

9. Sampling option 3 – modified segment design
Three-stage sample design
Small compact clusters with about households
Measure of size of EAs – calculated number of compact clusters
EAs selected systematically with PPS
Mapping and segmentation in all sample EAs
One compact cluster selected in each sample EA for listing, enumeration
MICS4 Survey Design Workshop

10. Relationship of sampling with other aspects of survey planning
Survey budget – may determine maximum sample size
Sampling plan should also take into account required timing of MICS results
Estimate costs and time related to PSUs – transportation, listing
Costs related to sample households – cost of interviewing (days of enumeration)
MICS4 Survey Design Workshop

11. Sampling and fieldwork organization
Effective balance of number of sample PSUs and cluster size
Dispersion of sample affects transportation costs, travel time
Size of team of enumerators and supervisor
Interviewer workload
MICS4 Survey Design Workshop

12. Factors that affect sample size
Budget and resource constraints
Timing and logistical considerations
Select key indicators
Required level of precision
Need for sub-national estimates
Regions, provinces, urban/rural domains
MICS4 Survey Design Workshop

13. Selecting key indicators
Person variables (rates)
Important indicator that will yield the largest sample size
Estimated rates between 15 and 20%
Target population that comprises a small proportion of the total population
Children aged 12 to 23 months
MICS4 Survey Design Workshop

14. Sample size determinants – sampling parameters
Level of precision – standard error, coefficient of variation (CV)
Acceptable level of error - margin of error, relative margin of error
Level of confidence – 95%
Design effect (DEFF) – depends mostly on level of clustering in the sample
Average household size
Proportion of base population in total population
Adjustment for non-response
MICS4 Survey Design Workshop

15. Use of previous MICS or DHS results
Review sample design of previous survey
Examine sample size and allocation to geographic domains
Study level of precision for key indicators
Design effects
95% confidence intervals
Results can be used to determine sample size and allocation for new MICS
MICS4 Survey Design Workshop

16. Formula for sample size calculation
Two similar spreadsheet templates for MICS4
Entry cell for each sampling parameter
Formula for calculating required number of sample households
Presentation and discussion of spreadsheets
MICS4 Survey Design Workshop

17. MICS4 Survey Design Workshop
Sample Size Formula
where
n is the required sample size, expressed as number of households, for the KEY indicator
4 is factor to achieve 95 percent level of confidence,
r is anticipated prevalence rate for key indicator,
1.1 is factor to raise sample size by 10 percent for potential nonresponse,
deff is shortened symbol for design effect,
0.12r is margin of error to be tolerated, defined as 12 percent of r (12 percent thus represents the relative margin of error),
p is proportion of total population that smallest group comprises, and
is average household size.
MICS4 Survey Design Workshop

18. Sample size reference table
Table 4.3 in Chapter 4 of MICS manual
Can be used for specific set of parameters:
Target population is 2.5% of total population
DEFF = 1.5
Nonresponse rate is 10%
Relative margin of error is 12%
95% level of confidence
MICS4 Survey Design Workshop

19. MICS4 Survey Design Workshop
Sample Size (Households) to Estimate Coverage Rates for Smallest Target Population
MICS4 Survey Design Workshop

20. Number of PSUs and cluster size
More PSUs and smaller clusters
Statistically more efficient – greater dispersion of sample
More costly – transportation, listing
Minimum number of PSUs to 400 at national level
Minimum of 30 PSUs for subnational domains
Number of sample households per cluster generally in range of 15 to 30 households
MICS4 Survey Design Workshop