A researcher wishes to estimate the prevalence of injecting drug use in an urban slum. Because members of this population are hidden and appear in no sampling frame, initial contacts refer the researcher to other users they know. This sampling method is called:

• A Quota sampling
• B Consecutive sampling
• C Snowball sampling ✓
• D Multistage sampling

Explanation

Snowball sampling recruits participants who then identify further participants from their own network. It is the standard approach for hard-to-reach or stigmatised populations such as injecting drug users, commercial sex workers and homeless persons who cannot be enumerated in advance. Quota sampling fills preset numbers in subgroups, while consecutive sampling takes every eligible subject presenting at a site, and neither relies on participant referral.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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