Quantitative Phase

We used a sampling frame of census block groups with at least 40% Black households for the quantitative phase. This yielded 256 census block groups (from a total of 450) from which we randomly selected addresses using the US Postal Service’s Delivery Sequence File. We sent letters about the study to prospective households before the interview team’s arrival. Teams of 2 Black interviewers then visited identified households to screen for eligibility, obtain written informed consent, and collect the data. Participants completed an interviewer-administered computer-assisted personal interviewing survey with an audio-computer-assisted self-interview section including questions about sexual behavior (these data were not included in our analyses). The response rate was 80%.