For selecting a research sample, which participant-recruitment mechanism does…

CONCEPT

Snowball sampling is a non-probability sampling method used when members of a population are difficult to identify or reach through a conventional sampling frame.

Recruitment proceeds through participant networks: each enrolled participant can identify further eligible people, so the sample grows through linked contacts.

APPLICATION

In this item, the mechanism being asked about is the chain by which current participants identify additional participants. That mechanism is referrals, so referrals are employed to select further sample members.

CONTRAST

• Field workers implement data-collection activities but are not the participant-to-participant recruitment mechanism.

• Opinion leaders may offer community access or information, but their influence does not define snowball recruitment.

• Surveyors administer questionnaires or take measurements; that role is distinct from generating a recruitment chain.

• Referrals create the linked chain through which one participant leads the researcher to another eligible participant.

CROSS-CHECK

If recruitment can be represented as participant A identifying B, and B identifying C, the process forms an expanding chain. This is precisely the referral structure associated with snowball sampling.