Quantifying the Benefits of Link-Tracing Designs for Partnership Network Studies.

Difficult-to-reach populations are frequently sampled through various link-tracing based designs, which rely on interpersonal networks to identify members of the population. This article examines the substantive returns to one such multiple-link tracing design in the Colorado Springs "Project 90" HIV risk networks study. Cross-links were respondents who were targeted for enrollment because of being named as partners by at least two other respondents in the sample. We compare cross-links to other respondents on sociodemographic characteristics and network properties using bivariate and multivariate adjusted statistics. We evaluate their contributions to observed network structure by creating a set of counterfactual networks deleting the information they provided. Results suggest that the link-tracing techniques led to identifying populations that would have otherwise been missed and that their absence would have underestimated potential HIV risk by distorting epidemiologically relevant measures within the network.