A district has 50,000 children aged 12–23 months. To estimate measles vaccination coverage, a two-stage cluster sampling is done: 30 clusters are selected, and 7 children are sampled per cluster. This design is BEST described as:
- A 30 × 7 systematic random sampling
- B WHO Expanded Programme on Immunization (EPI) coverage survey methodology ✓
- C Quota sampling
- D Stratified random sampling
Correct answer: B. WHO Expanded Programme on Immunization (EPI) coverage survey methodology
Explanation
The WHO EPI coverage survey methodology uses 30 cluster × 7 children = 210 children, a two-stage cluster sample where clusters are selected proportional to population size (PPS) and 7 children are sampled from each cluster by the random walk method. This is the standard design for national immunisation coverage surveys. Stratified sampling divides the population into strata first. Quota sampling is a non-probability method.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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