THE INMATE POPULATION PROJECTIONS DEVELOPED USING SLAM II HAVE BEEN 98.7 PERCENT ACCURATE OVER A 67-MONTH PERIOD FROM JULY 1973 THROUGH JANUARY 1979. THESE SAME PROJECTIONS OVER THE MOST RECENT 31 MONTHS HAVE BEEN 99.5 PERCENT ACCURATE WHEN COMPARED TO ACTUAL COUNTS TAKEN ON THE LAST DAY OF EACH MONTH. THE PERIOD OF SIMULATION VALIDATION WAS JULY 31, 1973 TO JUNE 30, 1978. THE MODEL WAS APPLIED TO A BASE POPULATION IN CUSTODY FOR JULY 31, 1973, AND EACH YEAR'S ADMISSIONS WERE INPUT THROUGH FY 1977-78. FUTURE ADMISSION TOTALS WERE DEVELOPED USING A MULTIPLE REGRESSION ANALYSIS OF POPULATION AT RISK (MALES AGED 18-29) AND UNEMPLOYMENT. ON THE BASIS OF KNOWN AND PROJECTED ADMISSIONS, THE MODEL COMPUTED THE PROBABILITY OF EACH INMATE'S BEING IN PRISON AT THE END OF EACH MONTH AND AGGREGATED THESE PROBABILITIES TO DETERMINE THE END-OF-MONTH POPULATION. GRAPHS AND TABLES REFLECT THE NUMBER OF INMATES PREDICTED BY THE MODEL TO BE IN PRISON FOR EACH MONTH SHOWN. DURING THE PERIOD FROM JULY 1973 THROUGH JANUARY 1979, THE PROJECTED END-OF-MONTH POPULATION WAS COMPARED TO THE HEAD COUNTS REPORTED FOR THE SAME DAY. FOR THIS PERIOD, THE MODEL OVERESTIMATED THE ACTUAL POPULATION IN 60 OF THE 67 MONTHS. THE GREATEST MAGNITUDE OF ERROR WAS 676 FOR DECEMBER 1974; THE SMALLEST MAGNITUDE OF ERROR WAS 3 FOR FEBRUARY 1978. THE RATE OF ERROR FOR EACH OF THE FISCAL YEARS IS PROVIDED. THE OVERALL AVERAGE RATE OF ERROR FOR THE ENTIRE PERIOD WAS 202 OUT OF AN AVERAGE 15,508 INMATE POPULATION, REPRESENTING AN AVERAGE RATE OF ERROR OF 1.3 PERCENT. THE AVERAGE RATE OF ERROR FOR THE MOST RECENT 31 MONTHS (JULY 1976 THROUGH JANUARY 1979) WAS 101 OUT OF AN AVERAGE INMATE POPULATION OF 19,135, REPRESENTING AN AVERAGE RATE OF ERROR OF 0.53 PERCENT. (AUTHOR ABSTRACT MODIFIED--RCB)