Policy
Simulation
Group

Pension Projection Models

More About the PSG Models

The three PSG models — PENSIM, SSASIM, GEMINI — work together to provide analysis of both employer-sponsored pensions and the social security (OASDI) program in the U.S. The working relationship between the models is best described as PENSIM and GEMINI being add-ons to SSASIM. The PSG models perform analysis using either a deterministic macrodemographic and macroeconomic environment in a single-scenario run or a stochastic environment in a multiple-scenario run.

SSASIM is a cell-based actuarial (CBA) model of social security trust fund solvency plus an simulator of social security benefits, taxes, and money's worth statistics for a handful of exemplary cohort individuals (ECI). Both the CBA mode and ECI mode models can be driven by either deterministic or stochastic projections of key macrodemographic and macroeconomic assumptions, as in the annual OASDI Trustees Report.

PENSIM is a microsimulation model of employer-sponsored pension (ESP) benefit accumulation and withdrawal behavior that is driven by the macro projections generated by SSASIM and produces estimates for a sample of individuals born in a specified year.

GEMINI is a microsimulation model that simulates social security benefits, taxes, and money's worth statistics for a representative cohort sample (RCS) generated by PENSIM. The GEMINI microsimulation results for many overlapping cohorts (OLC) can be aggregated by SSASIM into social security trust fund solvency estimates.

Getting Started with the PSG Models provides details about the CBA, ESP, RCS, and OLC modes of operation, and about the differences between the free educational version and the standard version of GEMINI, which requires registration and payment of an annual fee. (The educational version of GEMINI does not calculate OASDI benefits or taxes, which means it cannot be used for social security analysis, but it is useful in pension analysis.) The standard version of PENSIM is free. Also, details are provided about how the unregistered version of SSASIM can be used to execute the CBA mode benchmark test (to verify installation), but that all other SSASIM operations require registration and payment of an annual fee.

Descriptions of pension and social security analysis conducted by well-know users of the PSG models provide some understanding of their capabilities.

Additional insight into the nature of the models can be derived from a discussion of the key features of the PSG models.

The process of getting started with the PSG models is straight-forward.


This page was last revised on February 17, 2016.