I have two focuses of research areas. One is to focus on the epidemiology and prevention intervention of risky health behaviors, including drug use, mental health problems, overweight/obesity, risky sexual behaviors, other HIV-related behaviors, unintentional injuries and health disparities. The other focus is to apply advanced statistical methods to health and medical research, e.g. multi-level modeling (mixed modeling), survival analysis, structural equation modeling, e.g. exploratory and confirmatory factor analysis, mediation analyses, moderation analysis, path model, latent class modeling, and latent growth modeling, complier-average causal effect model, propensity score analysis et al. I had been a PI for two NIH R03 grants and published ~50 articles published in peer-reviewed journals.