Snowball sampling is a sampling method used by researchers to generate a pool of participants for a research study through referrals made by individuals who share a particular characteristic of research interest with the target population. It is also referred to as chain sampling or chain referral sampling.

In snowball sampling, a subject from an initial sample group is asked by researchers to recommend individuals to act as future participants. The prompting for recommendations may take the form of an informal question, such as “Who are your best friends?” The subjects who are recommended by these individuals and agree to participate in the research are then considered to be the first wave of participants. The subjects in the first wave will be asked to make their ...