Abbreviations: HIV, human immunodeficiency virus; IDU, injecting drug user; NHBS-IDU, National HIV Behavioral Surveillance System: Injecting Drug Users; n/a, not
applicable.
a Number of IDUs in the MSA was obtained from Brady
et al. [
17].
b "Sample size" includes all recruited persons regardless of eligibility.
c Sampling fraction was calculated as the NHBS-IDU sample size (column 2) divided by the IDU population size (column 1).
d Denominators do not include records without recruitment information, lost records, or persons excluded based on validity of response or gender.
e Percentage of non-seed participants who said the person who gave them the coupon was a stranger.
f Did not use multiple field sites.
g Race/ethnicity cross-recruitment not calculated for San Juan as 99% were Hispanic. The Norfolk sample was 87% Black and the St Louis sample was 91% Black.
h Total for population size, sample size, proportion eligible, and proportion recruited by a stranger; median value for sampling fraction.