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Respondent-driven Sampling Estimators Under Real and Theoretical Recruitment Conditions of Female Sex Workers in China

Verdery, Ashton M.a; Merli, M. Giovannab; Moody, Jamesc,d; Smith, Jeffrey A.e; Fisher, Jacob C.f

doi: 10.1097/EDE.0000000000000335
Infectious Disease

We compare the performance of multiple respondent-driven sampling estimators under different sample recruitment conditions in hidden populations of female sex workers in the midst of China’s ongoing epidemic of sexually transmitted infections. We first examine empirically calibrated simulations grounded in survey data to evaluate the relative performance of each estimator under ideal sampling conditions consistent with respondent-driven sampling assumptions and under conditions that mimic observed respondent-driven sampling recruitment processes. One estimator, which incorporates respondents’ reports on their network of contacts, substantially out-performs the others under all conditions. We then apply the estimators to empirical samples of female sex workers collected in two Chinese cities that include unique data on respondents’ networks. These empirical results are consistent with the simulation results, suggesting that traditional respondent-driven sampling estimators overestimate the proportion of female sex workers working in low tiers of sex work and are likely to overstate the sexually transmitted infection risk profiles of these populations.

From the aDepartment of Sociology and Criminology, Population Research Institute, The Pennsylvania State University, University Park, PA; bDepartment of Sociology and Duke Global Health Institute, Sanford School of Public Policy, Duke Population Research Institute, Duke University, Durham, NC; cDepartment of Sociology, Duke Population Research Institute, Duke University, Durham, NC; dKing Abdulaziz University, Jeddah, Saudi Arabia; eDepartment of Sociology, University of Nebraska, Lincoln, NE; and fDepartment of Sociology, Duke University, Durham, NC.

Submitted 25 August 2014; accepted 20 May 2015.

Editors’ note: a commentary on this article appears on page 625.

The analyses described here are funded by NICHD Grant 1 R01 HD068523 (Merli, PI) and Grant 1 R01 HD075712 (Moody, PI). The collection of the data grounding the simulations and empirical analyses was funded through multiple sources. Funding for the collection of the PLACE-RDS Comparison Study data was provided by USAID under the terms of cooperative agreements GPO-A-00-03-00003-00 and GPO-A-00-09-00003-0; by NICHD through the UNC R24 “Partnership for Social Science Research on HIV/AIDS in China” (Henderson, PI; by UNICEF, UNDP, World Bank, and WHO through the “WHO Rapid Syphilis Test Project (WHO A70577)”; by the Duke University and University of North Carolina Center(s) for AIDS Research; and by the National Center for STD Control in China. The PLACE-RDS Comparison Study was led by Sharon Weir (PI), with co-investigators, Xiangsheng Chen and M. Giovanna Merli. The Shanghai Women’s Health Survey was funded by an NICHD/NIDA Grant R21HD047521 (Merli, PI) and a Ford Foundation grant to the Shanghai Institute of Planned Parenthood Research (Ersheng Gao PI). We thank physicians and the outreach workers in the study areas for their hard work, and the study participants for their cooperation. We are also grateful to the Carolina Population Center for training support (T32 HD007168) and for general support (R24 HD050924). We thank participants at the Duke Network Analysis Center’s seminar series, and participants at the Sunbelt Social Networks Conference, especially Krista Gile and Mark Handcock, for helpful comments on an early version of this paper.

The authors report no conflict of interests.

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Correspondence: Ashton M. Verdery, Department of Sociology and Criminology, 211 Oswald Tower, The Pennsylvania State University, University Park, PA 16802.

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