Prevalence Estimation for Nonprobability Samples: Link-Tracing and Respondent-Driven Samplings

Music City Center 

Link-Tracing Sampling (LTS) methods are commonly used to estimate the prevalence of hidden populations. Respondent-Driven Sampling (RDS) is a variant of LTS that utilizes unique inference procedures for prevalence estimation. Challenges have been found with RDS in practice, such as long recruitment periods, homophily of samples, and violation of assumptions. The Vincent Link Tracing Sampling (VLTS), another variant of LTS, has been adopted as an alternative. However, little literature exists to guide prevalence estimation for VLTS but with the prevalence estimation procedure of RDS being applied crudely. Drawing on a study conducted in gold mining areas of the Kédougou district in Senegal that used RDS and VLTS methods to estimate prevalence of sex trafficking in 2021 and 2024, respectively, we study and compare the two methods. A survey of 561 respondents guided by RDS indicated 19% of women who engaged in commercial sex had experienced sex trafficking. Endline surveys of 850 respondents showed prevalence of 51%, a notable rise from baseline. We present reliable prevalence estimates for both methods, providing evidence for addressing the problem.

Link-Tracing Sampling

Respondent-Driven Sampling

Prevalence Estimation

Senegal

Nonprobability Samples

Hidden Population 

Survey Research Methods Section