A public health team wants to estimate HIV prevalence among injecting drug users, a hidden population with no sampling frame. They recruit a few initial contacts who then refer other members of their network. This sampling method is called:
- A Purposive sampling
- B Snowball sampling ✓
- C Quota sampling
- D Convenience sampling
Correct answer: B. Snowball sampling
Explanation
Snowball sampling is a non-probability technique in which initial participants recruit further subjects through their social networks, making it suitable for hard-to-reach groups such as injecting drug users, commercial sex workers and homeless persons. Purposive sampling relies on deliberate investigator selection by predefined criteria, quota sampling fills preset quotas from strata, and convenience sampling simply takes whoever is accessible without referral chains.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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