10! WORLD MODEL INSTRUCTIONS. CHAINS TO '$WORLDD'. 20! S.R. RINGLEE 20/8/72 30 INPUT"DO YOU NEED INSTRUCTIONS (YES OR NO) ";Y1$ 40 IF Y1$="NO" THEN 740 50 PRINT 60 PRINT"WORLD MODEL IS A HYPOTHETICAL DESCRIPTION OF THE WORLD" 70 PRINT"'SYSTEM'. WRITTEN BY JAY FORRESTER OF MIT AND DESCRIBED IN" 80 PRINT"HIS BOOK 'WORLD DYNAMICS' (IN THE LIBRARY UNDER HD82.F63)," 90 PRINT"IT MATHEMATICALLY PORTRAYS THE RELATIONS AMONG POPULATION," 100 PRINT"FOOD PRODUCTION, CAPITAL INVESTMENTPOLLUTION, NATURAL RE-" 110 PRINT"SOURCES, AND 'QUALITY OF LIFE'. IN THE BASIC VERSION, THE" 120 PRINT"USER ENTERS CERTAIN ASSUMPTIONS ABOUT CURRENT RATES OF BIRTH," 130 PRINT"DEATH, ETC., AND THEN VIEWS THE OUTPUT WHICH CORRESPONDS TO" 140 PRINT"THE 'LEVELS' OF FUNDAMENTAL VARIABLES OVER TIME. TO UNDER-" 150 PRINT"STAND THIS, YOU SHOULD FIRST READ FORRESTER'S BOOK.": PRINT 160 PRINT"----->INPUT ASSUMPTIONS:":PRINT 170 PRINT" (1) BR: THIS EQUALS THE 'BRN1' (BIRTH RATE-NORMAL, YEA1)" 180 PRINT" IN FORRESTER'S MODEL. IT IS EXPRESSED IN FRACTIONS/" 190 PRINT" YEAR, AND GIVES A MEASURE OF BIRTH RATE IN 1970." 200 PRINT" TO LEAVE THIS UNCHANGED (I.E., NO ABRUPT INCREASE" 210 PRINT" OR DECREASE IN THE BIRTH IN 1970), INPUT A '1'; TO" 220 PRINT" RAISE OR LOWER IT, INPUT SOME NUMBER HIGHER OR LOWER" 230 PRINT" THAN 1: 1.7, OR .25. FOR EXAMPLE, IF A RADICAL BIRTH" 240 PRINT" CONTROL PROGRAM INTRODUCED IN970, REDUCED THE BIRTH" 250 PRINT" RATE BY 75%, INPUT A '.25' FOR BR.": PRINT 260 PRINT" (2) DR: THIS EQUALS THE 'DRN1' (DEATH RATE-NORMAL, YEAR 1)" 270 PRINT" AND CORRESPONDS TO THE BIRTH RATE, ABOVE. TO LEAVE" 280 PRINT" 1970'S VALUE UNCHANGED, INPUT A '1'; OTHERWISE, YOU" 290 PRINT" MAY ELECT TO RAISE OR LOWER THIS FRACTIONALLY." 300 PRINT 310 PRINT" (3) NR: THIS EQUALS THE 'NRUN1' (NATURAL RESOURCE USAGE RATE-" 320 PRINT" NORMAL,EAR 1) IN NATURAL RESOURCE UNITS/PERSON/" 330 PRINT" YEAR. AGAIN, THE NORMAL VAULE FOR 1970 IS '1'; A RADI-" 340 PRINT" CAL INCREASE IN THE USE OF NATURAL RESOURCES MIGHT" 350 PRINT" BE APPROXIMATED BY AN NR OF '2' (A 100% INCREASE)." 360 PRINT 370 PRINT" (4) POL: 'POLN1' (POLLUTION-NORMAL, YEAR 1) IN POLLUTION UNITS/" 380 PRINT" PERSON/YEAR. 1970'S 'NORMAL' VALUE IS '1', AND IN-" 390 PRINT" CREASES OR DECREASES IN 'POL' REFLECT YOUR PICY" 400 PRINT" CHANGES IN THE RATE OF POLLUTION GENERATION.":PRINT 410 PRINT" (5) FC: 'FC1' (FOOD COEFFICIENT, YEAR 1) WHICH IS DIMENSION-" 420 PRINT" LESS. THIS MEASURES THE 'FOOD RATIO' (UNITS PER CAPITA)" 430 PRINT" IN 1970, AND IS '1' UNLESS YOU MAKE POLICY ASSUMP-" 440 PRINT" TIONS ABOUT THE AVAILABILITY OF FOOD BY INCREASING OR" 450 PRINT" DECREASING THIS.": PRINT 460 PRINT" (6) CI: 'CIGN1' (CAPITAL INVESTMENT GENERATION-NORMAL,EAR" 470 PRINT" 1), WHICH FOR 1970 IS USUALLY '1', MEASURES THE RATE" 480 PRINT" OF CAPITAL INVESTMENT GENERATION IN CAPITAL UNITS/" 490 PRINT" PERSON/YEAR.":PRINT 500 PRINT"----->OUTPUT VARIABLES:": PRINT 510 PRINT" (1) P: POPULATION LEVEL, BILLIONS OF PEOPLE" 520 PRINT" (2) C: CAPITAL INVESTMENT LEVEL, CAPITAL UNITS" 530 PRINT" (3) W: POLLUTION LEVEL, UNITS OF POLLUTION" 540 PRINT" (4) N: NATURAL RESOURCES, IN UNITS" 550 PRINT" (5) Q: QUATY OF LIFE, IN SATISFACTION UNITS" 560 PRINT 570 PRINT"----->USING THE MODEL:":PRINT 580 PRINT"(A) FOR A FIRST TRY, ASSUME NOTHING CHANGES IN 1970 (ALL" 590 PRINT" 6 COEFFICIENTS=1) AND SEE THE RESULTS." 600 PRINT"(B) NOTE THE DISASTROUS RESULTS (PRIMARILY DUE TO NATURAL RESOURCE " 610 PRINT" DEPLETION). TO REMOVE NATURAL RESOURCED AS A CONSTRAINT," 620 PRINT" ARBITRARILY REDUCE 'NR' (NR USAGE RATE) IN 1970 TO '.25'." 630 PRINT"(C) NOTE CATASTROPHIC RESULTS (DUE TO THE LK OF AN 'NR' CONSTRAINT" 640 PRINT" ON INDUSTRIALIZATION, THUS CAUSING EXTRAORDINARY POLLUTION)." 650 PRINT" NOW REMOVE POLLUTION AS A CONSTRAINT (ALONG WITH NR) BY" 660 PRINT" MAKING BOTH NR AND POL EQUAL TO, SAY, .25." 670 PRINT"(D) CONTINUE TRYING TO AVOID CATASTROPHE.": PRINT 680 GOTO 710 690 PRINT"TO EXTEND THE RESULTS INTO THE FUTURE PAST 2100, 'LIST' LINES" 700 PRINT"130 & 1410, AND CHANGE THE 'TO' VARIABLE.": PRINT 710! 720 PRINT"----->HELP. FOR HELP, READ FOESTER." 730 PRINT 740 CHAIN "$WORLDD" 750 END