Pension Projection Models


This is a brief description of just one of the PSG models, a unit of three that work seamlessly together as described on the homepage.

GEMINI a dynamic microsimulation model for analyzing the lifetime implications of social security policies for a large sample of people born in the same year.

Initial development of GEMINI was funded exclusively by the Policy Simulation Group during 2000 and 2001.

GEMINI uses as input birth cohort samples generated by PENSIM to represent the demographic and economic characteristics of historical birth cohorts.

GEMINI incorporates the same kind of OASDI program logic (including individual accounts) as used in the micro model of SSASIM, with almost all assumption and policy parameters read from the SSASIM input database.

GEMINI produces output files that contain detailed information about the life events and annual OASDI program experience of each individual in the cohort sample used as input.

The current version of GEMINI produces these detailed output files for a cohort sample of 100,000 life histories (plus spouses and children) in just a couple of minutes on a fast personal computer (see fast-running).

The social security results produced by GEMINI compare favorably with simulated output from other simulation models (see extensively-validated).

GEMINI has been used in a number of social security analysis projects by well-known users.

This page was last revised on February 17, 2016.