In cluster sampling, a city is divided into 50 ward clusters, and 10 clusters are randomly selected; all households in selected clusters are surveyed. Compared to simple random sampling with equal total sample size, cluster sampling typically:
- A Increases precision and reduces cost
- B Increases precision and increases cost
- C Reduces precision but reduces cost ✓
- D Reduces both precision and cost equally
Correct answer: C. Reduces precision but reduces cost
Explanation
Cluster sampling reduces cost and logistical complexity because only selected clusters are surveyed, eliminating the need to list and visit every individual in the population. However, because individuals within a cluster tend to be similar (intra-cluster correlation), there is less statistical variability, resulting in reduced precision (larger design effect) compared to simple random sampling of the same size.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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