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FUTURE COMPUTING ENVIRONMENTS FOR MICROSIMULATION MODELING 173 the TRIM2 framework. Therefore, aging is carried out in TRIM, and a new TRIM2 master and active file pair must be prepared after the adjustment has been made. TABLE 6 1986 TRIM2 Default Active File Size Data Records No. of Fields No. of Records Size of Record (bytes) Total Size (MB) Family 11 63,741 44 2.80 Person 14 155,372 56 8.70 Adult 20 119,704 80 9.58 1986 active 21.08 The first step is to adjust the household weights to match the population projections being used. The weeks worked and other labor force variables are then modified to simulate changes in the economy. These two steps are carried out with the POPAGE and CSWORK master routines. The third step uses the ECONAGE master routine to simulate inflation and real growth of different types of income. Both the POPAGE and ECONAGE master routines are based on modules originally coded for the MATH model (see History above). (The above description greatly simplifies the aging process described in detail in the TRIM2 Reference Manual [Webb et al., 1986].) For several reasons the current TRIM2 aging process is not extensively used. First, it is difficult to explain the methodology behind the economic adjustment procedure that attempts to achieve specified inflation and unemployment rates. Second, the master routine that changes the unemployment rate to hit a target figure uses a matrix of transition probabilities from one labor force status to another based on data from the late 1970s. Third, the work must be done within the older TRIM framework. Within the TRIM2 framework the master routines AINC and TALLY can be used to make much simpler adjustments to the underlying income data. For example, the AINC master routine is regularly used to adjust the asset income reported on the CPS since these data suffer from underreporting. AINC can also be used to adjust various income data up or down as a quick method of economic aging. A custom FORTRAN TALLY routine could also be used to adjust income variables in order to carry out a simple economic aging scenario. Operating Characteristics A large number of operating characteristics are available for use in TRIM2. Some of the major simulation modules that implement tax/transfer programs are as follows: federal insurance contribution act payroll taxes (FICAT), federal