Which sampling method relies on existing participants to recruit further participants through their networks?

• A. Stratified sampling
• B. Systematic sampling
• C. Convenience sampling
• D. Snowball sampling

Answer: (D)

Snowball sampling grows a study by tapping into participants’ social connections. It starts with a few individuals who meet the criteria, and these people are asked to refer others they know who also fit the study. Those new participants then refer more people, and the referrals keep spreading like a snowball. This approach is especially useful for hard-to-reach or hidden groups where a complete list of potential participants isn’t available or where trust within a network is important.

Because recruitment depends on who participants know, rather than on random selection, this method isn't aiming for random representation in the population. In contrast, other methods involve dividing the population into groups and sampling from them randomly, selecting every nth person on a list, or using whoever is easiest to access—none of these rely on chain referrals through networks.