globals [productivity-reds productivity-blues life-expectancy-reds life-expectancy-blues grass-growth-rate energy-from-grass-reds energy-from-grass-blues government-budget-reds government-budget-blues knowledge-reds knowledge-blues productivity-of-the-young-reds productivity-of-the-young-blues] turtles-own [energy age children] breed [blue-turtles blue-turtle] breed [red-turtles red-turtle] to setup ca ask patches [set pcolor one-of [green brown]] create-blue-turtles initial-number-of-blue-citizens [setxy random-xcor random-ycor set energy random 10 set color blue set size 2 set age random 180] create-red-turtles initial-number-of-red-citizens [setxy random-xcor random-ycor set energy random 10 set color red set size 2 set age random 180] do-plots end to go ifelse technical-progress-reds? [set-productivity-reds] [set productivity-reds 0] ifelse technical-progress-blues? [set-productivity-blues] [set productivity-blues 0] set energy-from-grass-reds 25 + productivity-reds set energy-from-grass-blues 25 + productivity-blues set life-expectancy-reds 180 + sqrt (ticks + productivity-reds) set life-expectancy-blues 180 + sqrt (ticks + productivity-blues) ifelse non-renewable-resources? [set-grass-growth-rate] [set grass-growth-rate 10] ask turtles[move-turtle display-label] let temp random 2 ifelse temp = 0 [ask red-turtles [eat-grass-reds death-reds] ask blue-turtles [eat-grass-blues death-blues]] [ask blue-turtles [eat-grass-blues death-blues] ask red-turtles [eat-grass-reds death-reds]] ask patches with [pcolor = brown] [grow-grass] if redistribution-reds? or education-reds? [ask red-turtles [pay-taxes-reds]] if redistribution-blues? or education-blues? [ask blue-turtles [pay-taxes-blues]] if redistribution-reds? [ask red-turtles [redistribution-of-resources-reds]] if redistribution-blues? [ask blue-turtles [redistribution-of-resources-blues]] if education-reds? [implement-education-system-reds] if education-blues? [implement-education-system-blues] ifelse birth-control-reds? [reproduction-conditions1-reds] [reproduction-conditions2-reds] ifelse birth-control-blues? [reproduction-conditions1-blues] [reproduction-conditions2-blues] ask patches with [pcolor = brown] [grow-grass] if shocks? [do-shock] if count red-turtles = 0 or count blue-turtles = 0 [stop] if government-budget-reds < -500000 [user-message ( word "Default of the State of the reds") ask red-turtles [die]] if government-budget-blues < -500000 [user-message ( word "Default of the State of the blues") ask blue-turtles [die]] tick do-plots end to implement-education-system-reds let education-expenditure-reds (education-expenditure-percapita-reds * count red-turtles with [age < (30 + round(life-expectancy-reds / 10))]) set government-budget-reds (government-budget-reds - education-expenditure-reds - 2000) set knowledge-reds (knowledge-reds + (1 + random 1) * education-expenditure-reds) set productivity-of-the-young-reds (2 * education-expenditure-percapita-reds) end to implement-education-system-blues let education-expenditure-blues (education-expenditure-percapita-blues * count blue-turtles with [age < (30 + round(life-expectancy-blues / 10))]) set government-budget-blues (government-budget-blues - education-expenditure-blues - 2000) set knowledge-blues (knowledge-blues + (1 + random 1) * education-expenditure-blues) set productivity-of-the-young-blues (2 * education-expenditure-percapita-blues) end to set-productivity-reds set productivity-reds sqrt (0.1 * ticks + 2 * count red-turtles with [age >= (30 + round(life-expectancy-reds / 10)) and age <= (150 + round(life-expectancy-reds / 20))] + (0.5 - productivity-of-the-young-reds) * count red-turtles with [age < (30 + round(life-expectancy-reds / 10))] + 0.2 * count red-turtles with [age > (150 + round(life-expectancy-reds / 20))]+ 0.1 * knowledge-reds + random-normal 0 1) end to set-productivity-blues set productivity-blues sqrt (0.1 * ticks + 2 * count blue-turtles with [age >= (30 + round(life-expectancy-blues / 10)) and age <= (150 + round(life-expectancy-blues / 20))] + (0.5 - productivity-of-the-young-blues) * count blue-turtles with [age < (30 + round(life-expectancy-blues / 10))] + 0.2 * count blue-turtles with [age > (150 + round(life-expectancy-blues / 20))]+ 0.1 * knowledge-blues + random-normal 0 1) end to set-grass-growth-rate set grass-growth-rate 10 - ln (1 + 0.001 * ticks + 0.00001 * count turtles) end to move-turtle let steps random 10 right random 360 fd steps set energy energy - steps set age (age + 1) end to eat-grass-reds if pcolor = green [set pcolor brown set energy (energy + energy-from-grass-reds)] end to eat-grass-blues if pcolor = green [set pcolor brown set energy (energy + energy-from-grass-blues)] end to death-reds if energy < 0 or age > life-expectancy-reds [die] end to death-blues if energy < 0 or age > life-expectancy-blues [die] end to reproduction-conditions1-reds ask red-turtles with [age >= (30 + round(life-expectancy-reds / 10)) and age <= (150 + round(life-expectancy-reds / 20)) and children < 51] [generate-red-turtle] end to reproduction-conditions2-reds ask red-turtles with [age >= (30 + round(life-expectancy-reds / 10)) and age <= (150 + round(life-expectancy-reds / 20))] [generate-red-turtle] end to generate-red-turtle if count red-turtles in-radius 1 > 2 and energy > 50 + round (count red-turtles / 10) [set energy (energy / 2) set children (children + 1) hatch 1[set energy random 50 set age 0]] end to reproduction-conditions1-blues ask blue-turtles with [age >= (30 + round(life-expectancy-blues / 10)) and age <= (150 + round(life-expectancy-blues / 20)) and children < 51] [generate-blue-turtle] end to reproduction-conditions2-blues ask blue-turtles with [age >= (30 + round(life-expectancy-blues / 10)) and age <= (150 + round(life-expectancy-blues / 20))] [generate-blue-turtle] end to generate-blue-turtle if count blue-turtles in-radius 1 > 2 and energy > 50 + round (count blue-turtles / 10) [set energy (energy / 2) set children (children + 1) hatch 1[set energy random 50 set age 0]] end to grow-grass if random-float 100 < grass-growth-rate [set pcolor green] end to display-label ifelse show-energy? [set label round energy][set label "" ] end to pay-taxes-reds set energy (energy - marginal-tax-rate-reds * energy) set government-budget-reds (government-budget-reds + marginal-tax-rate-reds * energy) end to pay-taxes-blues set energy (energy - marginal-tax-rate-blues * energy) set government-budget-blues (government-budget-blues + marginal-tax-rate-blues * energy) end to redistribution-of-resources-reds if energy < poverty-line-reds [let subsidy poverty-reduction-reds * (poverty-line-reds - energy) set energy (energy + subsidy) set government-budget-reds (government-budget-reds - subsidy - 1)] end to redistribution-of-resources-blues if energy < poverty-line-blues [let subsidy poverty-reduction-blues * (poverty-line-blues - energy) set energy (energy + subsidy) set government-budget-blues (government-budget-blues - subsidy - 1)] end to do-shock let probability-of-shock random-float 1 let population-striken random 4 if population-striken = 0[if probability-of-shock < 0.05 and probability-of-shock > 0.001 [ask n-of ((count turtles) * random-float 0.1) turtles [die]] if probability-of-shock < 0.001 [ask n-of ((count turtles) * random-float 0.4) turtles [die]]] if population-striken = 1[if probability-of-shock < 0.05 and probability-of-shock > 0.001 [ask n-of ((count turtles with [age < 50]) * random-float 0.1) turtles with [age < 50] [die]] if probability-of-shock < 0.001 [ask n-of ((count turtles with [age < 50]) * random-float 0.4) turtles with [age < 50] [die]]] if population-striken = 2[if probability-of-shock < 0.05 and probability-of-shock > 0.001 [ask n-of ((count turtles with [age >= 50 and age <= 150]) * random-float 0.1) turtles with [age >= 50 and age <= 150][die]] if probability-of-shock < 0.001 [ask n-of ((count turtles with [age >= 50 and age <= 150]) * random-float 0.4) turtles with [age >= 50 and age <= 150][die]]] if population-striken = 3[if probability-of-shock < 0.05 and probability-of-shock > 0.001 [ask n-of ((count turtles with [age > 150]) * random-float 0.1) turtles with [age > 150] [die]] if probability-of-shock < 0.001 [ask n-of ((count turtles with [age > 150]) * random-float 0.4) turtles with[age > 150] [die]]] end to do-plots set-current-plot "Totals" set-current-plot-pen "red-citizens" plot count red-turtles set-current-plot-pen "blue-citizens" plot count blue-turtles set-current-plot-pen "resources" plot (count patches with [pcolor = green]) set-current-plot-pen "red-poor" plot count red-turtles with [energy < poverty-line-reds] set-current-plot-pen "blue-poor" plot count blue-turtles with [energy < poverty-line-blues] set-current-plot "Population composition reds" set-current-plot-pen "young" plot ((count red-turtles with [age < (30 + round(life-expectancy-reds / 10))]) / count red-turtles) set-current-plot-pen "old" plot ((count red-turtles with [age > (150 + round(life-expectancy-reds / 20))]) / count red-turtles) set-current-plot-pen "adult" plot ((count red-turtles with [age >= (30 + round(life-expectancy-reds / 10)) and age <= (150 + round(life-expectancy-reds / 20))]) / count red-turtles) set-current-plot "Population composition blues" set-current-plot-pen "young" plot ((count blue-turtles with [age < (30 + round(life-expectancy-blues / 10))]) / count blue-turtles) set-current-plot-pen "old" plot ((count blue-turtles with [age > (150 + round(life-expectancy-blues / 20))]) / count blue-turtles) set-current-plot-pen "adult" plot ((count blue-turtles with [age >= (30 + round(life-expectancy-blues / 10)) and age <= (150 + round(life-expectancy-blues / 20))]) / count blue-turtles) end ; Copyright 2011 Dario Sansone. All rights reserved. ; Supervisor: Pietro Terna, Faculty of Economics, University of Turin @#$#@#$#@ GRAPHICS-WINDOW 677 343 1022 709 33 33 5.0 1 10 1 1 1 0 0 0 1 -33 33 -33 33 1 1 1 ticks BUTTON 14 10 77 43 NIL setup\n NIL 1 T OBSERVER NIL NIL NIL NIL BUTTON 14 50 77 83 NIL go T 1 T OBSERVER NIL NIL NIL NIL PLOT 11 175 331 409 Totals time total 0.0 10.0 0.0 10.0 true true PENS "red-citizens" 1.0 0 -2674135 true "blue-citizens" 1.0 0 -13345367 true "resources" 1.0 0 -10899396 true "red-poor" 1.0 0 -6459832 true "blue-poor" 1.0 0 -955883 true SWITCH 256 128 376 161 show-energy? show-energy? 1 1 -1000 MONITOR 340 174 397 219 citizens count turtles 17 1 11 MONITOR 546 172 613 217 resources count patches with [pcolor = green] 17 1 11 SWITCH 81 88 248 121 technical-progress-reds? technical-progress-reds? 0 1 -1000 SWITCH 380 127 483 160 shocks? shocks? 1 1 -1000 PLOT 343 418 659 652 Population composition reds time turtles 0.0 10.0 0.0 1.0 true true PENS "young" 1.0 0 -13345367 true "adult" 1.0 0 -16777216 true "old" 1.0 0 -7500403 true MONITOR 610 497 667 542 young count red-turtles with [age < (30 + round(life-expectancy-reds / 10))] 17 1 11 MONITOR 610 544 667 589 adult count red-turtles with [age >= (30 + round(life-expectancy-reds / 10)) and \n age <= (150 + round(life-expectancy-reds / 20))] 17 1 11 MONITOR 610 590 667 635 old count red-turtles with [age > (150 + round(life-expectancy-reds / 20))] 17 1 11 MONITOR 404 268 496 313 productivity-reds round productivity-reds\n 17 1 11 MONITOR 341 365 453 410 life-expectancy-reds round life-expectancy-reds 17 1 11 SWITCH 302 10 479 43 non-renewable-resources? non-renewable-resources? 1 1 -1000 MONITOR 402 173 541 218 resources-growth-rate grass-growth-rate 5 1 11 SLIDER 81 10 296 43 initial-number-of-red-citizens initial-number-of-red-citizens 0 1000 1000 100 1 NIL HORIZONTAL SWITCH 339 49 480 82 birth-control-reds? birth-control-reds? 1 1 -1000 SWITCH 745 10 908 43 redistribution-reds? redistribution-reds? 1 1 -1000 MONITOR 341 316 480 361 NIL government-budget-reds\n 0 1 11 SLIDER 802 50 982 83 marginal-tax-rate-reds marginal-tax-rate-reds 0 0.2 0.01 0.01 1 NIL HORIZONTAL SLIDER 711 92 883 125 poverty-line-reds poverty-line-reds 0 100 50 10 1 NIL HORIZONTAL SLIDER 711 132 883 165 poverty-reduction-reds poverty-reduction-reds 0 1 0.9 0.1 1 NIL HORIZONTAL SWITCH 914 10 1058 43 education-reds? education-reds? 1 1 -1000 SLIDER 894 92 1127 125 education-expenditure-percapita-reds education-expenditure-percapita-reds 0 0.2 0.02 0.02 1 NIL HORIZONTAL MONITOR 341 268 401 313 red poor count red-turtles with [energy < poverty-line-reds] 17 1 11 MONITOR 420 221 519 266 total richness reds round(sum [energy] of red-turtles) 17 1 11 PLOT 11 419 327 653 Population composition blues NIL NIL 0.0 10.0 0.0 1.0 true true PENS "young" 1.0 0 -13345367 true "adult" 1.0 0 -16777216 true "old" 1.0 0 -7500403 true SWITCH 340 90 481 123 birth-control-blues? birth-control-blues? 1 1 -1000 SWITCH 81 129 250 162 technical-progress-blues? technical-progress-blues? 0 1 -1000 SLIDER 82 47 294 80 initial-number-of-blue-citizens initial-number-of-blue-citizens 0 1000 1000 100 1 NIL HORIZONTAL SWITCH 725 176 892 209 redistribution-blues? redistribution-blues? 1 1 -1000 SWITCH 901 176 1050 209 education-blues? education-blues? 1 1 -1000 SLIDER 814 218 994 251 marginal-tax-rate-blues marginal-tax-rate-blues 0 0.2 0.01 0.01 1 NIL HORIZONTAL SLIDER 711 258 883 291 poverty-line-blues poverty-line-blues 0 100 50 10 1 NIL HORIZONTAL SLIDER 711 298 885 331 poverty-reduction-blues poverty-reduction-blues 0 1 0.9 0.1 1 NIL HORIZONTAL SLIDER 900 258 1138 291 education-expenditure-percapita-blues education-expenditure-percapita-blues 0 0.2 0.02 0.02 1 NIL HORIZONTAL MONITOR 340 221 417 266 red citizens count red-turtles 17 1 11 MONITOR 523 221 600 266 blue citizens count blue-turtles 17 1 11 MONITOR 524 268 583 313 blue poor count blue-turtles with [energy < poverty-line-blues] 17 1 11 MONITOR 524 315 662 360 NIL government-budget-blues 0 1 11 MONITOR 588 268 700 313 productivity-blues round (productivity-blues) 17 1 11 MONITOR 526 363 638 408 life-expectancy-blues round life-expectancy-blues 17 1 11 MONITOR 603 220 704 265 total richness blues round(sum [energy] of blue-turtles) 17 1 11 MONITOR 278 493 335 538 young count blue-turtles with [age < (30 + round(life-expectancy-blues / 10))] 17 1 11 MONITOR 278 540 335 585 adult count blue-turtles with [age >= (30 + round(life-expectancy-blues / 10)) and \n age <= (150 + round(life-expectancy-blues / 20))] 17 1 11 MONITOR 278 588 335 633 old count blue-turtles with [age > (150 + round(life-expectancy-blues / 20))] 17 1 11 @#$#@#$#@ WHAT IS IT? ----------- The model explores the stability, the evolution and the sustainability of a system with technical progress, random shocks, non renewable resources, birth control and a welfare state. HOW IT WORKS ------------ The program creates a world with renewable resources and in which each citizen is generated, moves, eats, reproduces, gets old and dies. The user, thanks to different sliders and switches, can introduces more variables and he can implement different kind of policies. The fertility rate and the life expectancy change over time. HOW TO USE IT ------------- 1. Adjust the slider parameters (see below), or use the default settings. 2. Press the SETUP button. 3. Press the GO button to begin the simulation. 4. Look at the monitors to check the variables of this model 5. Look at the TOTAL and POPULATION COMPOSITION plots to watch the population fluctuation over time Parameters: NUMBER-OF-CITIZENS: The initial size of the population TECHNICAL-PROGRESS?:Whether or not to introduce progress by means of increasing productivity SHOW-ENERGY?: Whether or not to show the energy of each citizen as a number NON-RENEWABLE-RESOURCES?: Whether or not to reduce gradually the growth rate of the resources BIRTH-CONTROL?: Whether or not to enable only adults citizen with less than 50 children to reproduce themselves SHOCKS?: Whether or not to introduce random shocks which may modify the composition of the population REDISTRIBUTION?: Whether or not to introduce a welfare state EDUCATION?:Whether or not to introduce an education system MARGINAL-TAX-RATE: the tax burden, i.e. citizens have to pay a tax which is equal to the marginal tax rate multiplied by their energy POVERTY-LINE: citizens which have less energy than the poverty line are considered poor POVERTY-REDUCTION: the import of the subsidy received by poor citizens is equal to poverty reduction times the difference between poverty line and the energy of the citizen EDUCATION-EXPENDITURE-PERCAPITA: public expenditure per capita in order to offer a public education to young citizens THINGS TO NOTICE ---------------- See the different patterns of population and population composition when different switches are activated. Some choice are sustainable in the long run and other ones tends to bring citizens towards extinction or are financial unsustainable. Note that is very important the time in which some policies such as education system or welfare state are implemented. The results may be very different both in the short run and in the long run. Note that the tax burder play a key role in stimulating or dampening the population growth. THINGS TO TRY ------------- Try to modify the initial number of citizens. Does the shorth run equilibrium change? Try to activate only some switches and see the effects. Try to balance a good welfare state and education sistem with their financial sustainability: if the government debt is more than 500000, there is the default of the State. Try to see, modifing sliders and activating switches, if there is a long-run equilibrium, a trend or if the model is instable. EXTENDING THE MODEL ------------------- Some interesting things to add would be: pollution, diseases and health system, happyness of population and possibility of rebellions, different breeds which compete to survive. NETLOGO FEATURES ---------------- Note the use of let in order to create temporary variables. Note the use of global variables in order to set variables which affect all the citizens, such as productivity, life expectancy, grass growth rate, knowledge and government budget. Note the use of mathematical function, such as the square root or the natural logarithm, in order to consider decreasing marginal improvement in progress, life expectancy and growth rate of natural resources. RELATED MODELS -------------- Look at Wolf Sheep Predation for a model of interacting populations with limited resources and instability problems. CREDITS AND REFERENCES ---------------------- Paolo Bosi (a cura di), "Corso di scienza delle finanze", 2010 - Quinta edizione, Il Mulino. Cap. 7 - La spesa per il Welfare State Giovanni Pavanelli, "Valore, distribuzione, moneta: un profilo di storia del pensiero economico", 2010 - Seconda edizione, FrancoAngeli. Cap. 5.1 - Malthus e il Saggio sul principio della popolazione The World Bank, World Development Report 2008, "Agriculture for Development", Overview @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 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