Executive Summary Modeling Health Care Policy Alternatives We review three types of computational models commonly used to evaluate health care policy alternatives: microsimulation, system dynamics, and spreadsheet models. For each type of model we discuss its basic mechanisms, data requirements and other factors that may affect its scope, and the domain of application. We also discuss how to build better models and perform analyses that are currently out-of-scope by changing the type of data that are currently collected and access to those data. To improve modeling capabilities, we recommend fielding a health-focused, nationally representative, longitudinal study on individuals that would allow researchers to better understand decision-making surrounding health insurance take-up, as well as relationships among insurance status, health care access, and health outcomes. We also suggest improving access to linked data sources, such as employee-employer linked data, and developing more data sources focused on providers. In addition to data collection, we recommend that funding be provided to identify causal parameters and to clarify ranges of effects that have been reported in the literature. Finally, we suggest establishing a forum for routine communication between modelers and policymakers to ensure that model results are fully understood and can be applied effectively.