Improving Information for Social Policy Decisions -- The Uses of Microsimulation Modeling: Volume II, Technical Papers (1991)
Chapter: Output Facilities
can be met by using the existing simulation modules. If the user’s modeling needs require a new twist to an existing simulation module or a completely new simulation module, an experienced TRIM2 programmer can modify the necessary simulation module or write a custom TALLY master routine to carry out the required calculations. The only documentation on how to modify the TRIM2 source code is found in the TRIM2 Reference Manual.
As a very rough indication of the computer resources required for a sample TRIM2 run, the following data were collected from a sample TRIM2 program listing that executed two separate TRIM2 requests or run sequences. The job analyzed ran on an IBM System 3090 mainframe computer at the National Institutes of Health in May 1989. The first run sequence executed the SSI, AFDC, FSTAMP, AINC, and FICAT simulation modules on the 1986 TRIM2 database. This sequence required 335 CPU seconds and 10,800 input/output operations and used a maximum of 1,500 KB of memory. The second run sequence executed the FDIMPU, FEDTAX, and STATAX simulation modules on an active file produced by the first run sequence and required 140 CPU seconds and 11,800 input/output operations and used a maximum of 1,500 KB of memory.
Comparing Model Runs
TRIM2 permits comparison of two different simulation scenarios in several different ways. Each of the simulation modules has a set of default tables that can be used to determine the gross and net flows between governments and individuals and/or the number of units of analysis affected by a particular tax/transfer program. One major feature of TRIM2 is its ability to execute multiple instances of one or more simulation modules in the same job. This permits a user to study several scenarios in a single computer job.
The master routine SIMTAB was specially created to compare multiple simulations of the FSTAMP or AFDC simulation modules. The QUANT master routine can be used to compare different model runs by examining the incidence of taxation or receipt of income transfer across an income distribution classified by a quantile variable.
If the reporting requirements cannot be met by these techniques, a specialized reporting module or TALLY module can be coded in FORTRAN and linked into a custom TRIM2 program. Or the variables required for the analysis can be exported to an external file with the XPORT master routine for analysis by an external statistical package.
Output Facilities
Each of the operating characteristics executed in a TRIM2 job can produce a set of standard tables during the final or summary run phase of execution. For
