Respondent Driven Sampling

Respondent-driven sampling is a form of snowball sampling which allows researchers to make estimates about hidden population such as HIV/AIDS patients, injection drug users, sex workers, and men who have sex with men etc. It can be used to answer pertinent questions relating to the hidden population.  Respondent-driven sampling is currently in use.

A respondent-driven sample is collected via a snowballing design, where current subjects recruit their friends to be future subjects. Because subjects are not selected via simple random sampling, care must be taken when making estimates from this type of sample. It can be proved that if certain conditions are met and if the appropriate estimation procedures are used, then prevalence estimates from this type of sample are unbiased and if the appropriate conditions are not met, the estimates can be biased. Further, even if the appropriate conditions are met, the estimates from respondent-driven sampling can have very high variance due to bottlenecks in the underlying network structure of the hidden population.