A researcher asks an online support group for patients with a rare disorder to participate, and asks each participant to invite others with the same disorder to participate, who then recruit more participants. What nonprobability sampling technique is described?

• A. Snowball sampling
• B. Convenience sampling
• C. Purposive sampling
• D. Quota sampling

Answer: (A)

Snowball sampling is a nonprobability approach in which participants recruit others from their social networks. In this scenario, initial participants invite others with the same rare disorder, who then invite additional participants, creating a chain of referrals. This method is especially helpful for hard-to-reach or small populations because it leverages existing connections to grow the sample.

It isn’t convenience sampling, which would involve selecting whoever is easiest to access without a referral process. It isn’t purposive sampling, where researchers intentionally select individuals to meet specific criteria, independent of participant-driven recruitment. It isn’t quota sampling, which aims to fill predefined subgroups with predetermined numbers.