To study injecting drug use in an urban slum where no sampling frame exists, a researcher recruits initial contacts who then refer other members of the network until the required sample accumulates. This technique is called:

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

Explanation

Snowball sampling is a non-probability method in which initial participants recruit further subjects through their social contacts, making it useful for hidden or hard-to-reach populations such as injecting drug users or commercial sex workers. Quota sampling fills preset category quotas, purposive sampling selects subjects by deliberate judgement, and multistage sampling is a probability method proceeding through successive random stages such as districts then villages then households.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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