Comparison of Respondent Driven Sampling Estimators to Determine HIV Prevalence and Population Characteristics among Men Who Have Sex with Men in Moscow, Russia.

Analytically distinct estimators have been proposed for the calculation of population-based estimates derived from respondent-driven sampling (RDS), yet there have been few comparisons of the inferences from these estimators using empirical data. We compared estimates produced by unweighted analysis used to calculate sample proportions and by three available estimators that are used to calculate population proportions, RDS-I, RDS-II (Volz-Heckathorn), and Gile's RDS-SS. Data were derived from a cross-sectional, RDS study of men who have sex with men (MSM) conducted from October 2010 to April 2013 in Moscow, Russia (N = 1,376, recruitment depth: 31 waves). Analyses investigated the influence of key parameters: recruitment depth, homophily, and network size on sample and population estimates. Variability in results produced by the estimators and recruitment depth were statistically compared using the coefficient of variation (CV). Sample proportions had the least variability across different recruitment depths, compared to the RDS estimators. Population estimates tended to differ at lower recruitment depth but were approximately equal after reaching sampling equilibrium, highlighting the importance of sampling to greater recruitment depth. All estimators incorporate inverse probability weighting using self-reported network size, explaining the similarities in across population estimates and the difference of these estimates relative to sample proportions. Current biases and limitations associated with RDS estimators are discussed

Variability of sample proportion and estimators for select variables, as measured by coefficient of variation across estimators and recruitment depth.

<p>Variability of sample proportion and estimators for select variables, as measured by coefficient of variation across estimators and recruitment depth.</p

Demographic and HIV-related characteristics among RDS-recruited MSM in Moscow, Russia (N = 1,376).

<p>Demographic and HIV-related characteristics among RDS-recruited MSM in Moscow, Russia (N = 1,376).</p

RDS process indicators and seed characteristics in the recruitment of MSM in Moscow, Russia (2010–13).

<p>RDS process indicators and seed characteristics in the recruitment of MSM in Moscow, Russia (2010–13).</p

Sample and population proportion estimates of MSM with homosexual identity, by recruitment depth and estimation method.

<p>Table includes average network size and homophily at each recruitment depth; with exception of 95%CIs, RDS-II and RDS-SS estimates overlap; dashed lines represent 95%CIs.</p