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Alternative Model Designs: Program Participation Functions and the Allocation of Annual to Monthly Values in TRIM2, MATH, and HITSM
Constance F.Citro and Christine M.Ross
INTRODUCTION
The Transfer Income Model 2 (TRIM2) and the Micro Analysis of Transfers to Households (MATH) model are two microsimulation models that are heavily used for analysis of proposed changes to government tax and transfer programs. The Household Income and Tax Simulation Model (HITSM) is another static microsimulation model that has been used for policy analysis in the income support and tax areas. All three models fall into the class of “static” microsimulation models—that is, models that operate on a cross-sectional basis and make projections to future years using procedures for reweighting, or “aging,” their database to match outside projections of selected characteristics such as the demographic and labor force composition of the population.1 (In contrast, dynamic models apply transition probabilities for events such as birth, death, job change, and others to the records in their database, thereby “growing” their population year by year into the future; see Ross in this volume.)
Constance F.Citro is a staff officer at the National Research Council; she served as study director of the Panel to Evaluate Microsimulation Models for Social Welfare Programs. Christine M.Ross is on the staff of Mathematica Policy Research, Inc.; she served as research associate of the panel.
