 The results of this study suggest that a microsimulation model incorporating smoking and e-cigarette use transition rates from a Markov multi-state model, MSIM, accurately projected downstream prevalence of product use. Additionally, the model structure and parameters provide a foundation for estimating the behavioral and clinical impact of tobacco and e-cigarette policies. This article was authored by Eli Schwam, Farzad Nubri, Nancy Aragati and others.