In this type, initial group of respondents are selected. Those respondents are requested to provide the names of additional respondents who belong to the target population of interest. It is a sampling method that involves the assistance of study subjects to identify other potential subjects in studies where subjects are hard to locate such as sex workers, drug abusers, etc. This type of sampling technique works like a chain referral. Therefore it is also called chain referral sampling.
· Appropriate for small specialized population.
· Useful in studies involving respondents rare to find.
· It takes more time
· Most likely not representative
· Members of the population, who are little known, disliked or whose opinions conflict with the respondents, have low probability of being included.