A public health team wants to recruit intravenous drug users for a study on needle-sharing practices. Because no sampling frame exists for this hidden population, initial contacts are asked to refer other users they know, who in turn refer further participants. This sampling method is:
- A Quota sampling
- B Snowball sampling ✓
- C Purposive sampling
- D Cluster sampling
Correct answer: B. Snowball sampling
Explanation
Snowball sampling is a non-probability technique in which existing subjects recruit future subjects from their acquaintances, making it useful for hard-to-reach or stigmatised populations lacking a sampling frame. Quota sampling fills predetermined numbers in subgroups, purposive sampling relies on deliberate investigator selection of typical cases, and cluster sampling requires a defined frame of clusters with random selection, none of which matches the referral chain described.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.