Policy analysis through microsimulation: the STATS model

This article gives a nontechnical introduction to a microsimulation model developed by the Social Security Administration to consider the effects of tax and benefit proposals on the economic status of population groups. This model, the Simulated Tax and Transfer System (STATS) model, uses information from a nationally representative survey of households to calculate taxes or benefits for thousands of persons or families, case by case. Then the model aggregates across individual cases to produce estimates for economic and demographic groups of interest to policymakers. Groups are defined by such characteristics as family income, age, sex, and marital status. The article explains the model's microsimulation approach and its emphasis on the economic status of population groups. It describes the procedures for simulating taxes and benefits and then illustrates the use of the model by considering a proposal to change the way Social Security benefits are taxed. The article also discusses the primary data source and the extent to which it limits the types of estimates that the model can produce.