PROJECT SUMMARY Behavioral and social sciences researchers continue to struggle to reach, sample, count, engage and retain participants from socially disadvantaged and marginalized groups, or hard-to-reach populations. Hard-to-reach populations are often those experiencing health disparities for many diseases and conditions. Such populations include: persons experiencing homelessness and housing insecurity, chronic mental illness, out of school youth, sex workers, trafficked adolescent girls, undocumented immigrants, gang members, street children, people who use drugs, racial/ethnic minorities, and sexual and gender minorities such as transgender persons and men who have sex with men. There are many reasons why these groups are not fully represented or included in behavioral, social sciences, and clinical research. One reason is the lack of training on state-of-the-art methodologies to sample hard-to-reach populations and the advance statistical skills to analyze complex survey data within formal training programs. Moreover, the advanced methods needed to estimate their numbers are not taught in conventional behavioral, public health, and social sciences degree programs. These fundamental skills are needed to advance multiple lines of research to end health disparities, to be more inclusive of diverse populations in research, and to efficiently obtain samples of hard-to-reach populations in large enough numbers necessary for statistically powerful study designs. Many innovations for engaging, recruiting, and sampling hard-to-reach populations originate from HIV research but remain underutilized in other areas of behavioral and social sciences research. This H2R training grant will capitalize on our >15 years of research with hard-to-reach populations at risk for HIV, and a recent successful initiative, the Sampling Knowledge Hub at UCSF, to establish a core of short courses, strengthen mentorship, and initiate lines of research among hard-to-reach populations for trainees and mentors among graduate students and junior researchers at universities and public health practitioners of health departments in Northern California.

PROJECT NARRATIVE This program will train scholars and mentors on state-of-the-art methods for sampling, size estimation and engagement of hard-to-reach populations to improve social science and health disparities research.