Abstract
BACKGROUND: Network Scale-Up (NSU) is a promising tool in the size estimation of stigmatized behaviors. In NSU, participants from the general population describe the frequency of stigmatized behaviors in their network. To avoid underestimation, due to the invisibility of sensitive behaviors, NSU results should be adjusted by the Visibility Factor (VF). This manuscript aims to compare three VF calculation methods in sex work settings: Game of Contact (GC), Social Respect (SR), and Expert Opinion (EO). METHODS: In the GC method, we selected 20 names and asked 60 FSWs (Female Sex workers) (known as egos) the total number of their acquaintances (known as alters) with any of the 20 names, and of those, how many were aware that the ego was an FSW. In the SR method, we asked 600 participants from the general population about the number of FSWs they knew, and to rank their respect for FSWs on a scale of 1 to 5. Finally, we asked 14 experts in the field of HIV and health policy about the visibility rate of sex work in Iran. RESULTS: Based on EO, VF was as low as 38%. VF in GC was 67% (95% CI: 54%, 80%) for both male and female alters. SR suggested a VF of 77% (58%, 101%), which was higher in male than female respondents (83% vs. 62%). CONCLUSION: Different methods provide different VF estimates. For a fair comparison of studies, a concrete and standard method for VF calculation should be applied.