breed [ consumers consumer ] consumers-own [ happiness price_list1 price_list2 price_list3 price_list4 quantity ] globals [ whole_price_list1 whole_price_list2 whole_price_list3 whole_price_list4 cycle_# sold_quantities_firm1 sold_quantities_firm2 sold_quantities_firm3 sold_quantities_firm4 ] patches-own [ price1 price2 price3 price4 ] to setup ;; procedure to set up the world for the simulation. , ca set cycle_# 0 ;; set 0 the number of cycle and the sold quantity for each firm. set sold_quantities_firm1 0 set sold_quantities_firm2 0 set sold_quantities_firm3 0 set sold_quantities_firm4 0 ask patches [setup-firm?] setup-consumers end to setup-firm? ; procedure to create the four firms from patches and the non consumption area if (pycor <= 14) and (pycor > 0) and (pxcor < 0) and( pxcor >= -14) [set pcolor blue set price1 p1 ] if (pycor <= 0) and (pycor > -14) and (pxcor < 0) and( pxcor >= -14) [set pcolor pink set price2 p2 ] if (pycor <= 0) and (pycor > -14) and (pxcor >= 0) and( pxcor < 14) [set pcolor red set price3 p3 ] if (pycor > 0) and (pycor <= 14) and (pxcor >= 0) and( pxcor < 14) [set pcolor green set price4 p4 ] if (pycor > 14) [set pcolor white] if (pycor <= -14) [set pcolor white] if (pxcor >= 14) [set pcolor white] if (pxcor < -14) [set pcolor white] end to setup-consumers ; procedure to create consumers set-default-shape consumers "consumers" create-consumers consumer_number ; creates a number of consumers as from the slider in the interface ask consumers [ fd 10 set heading random 360 set color black set quantity random n_quantity + 1 set size 2 ;sets the quantity consumers want to buy as from the slider in the interface set happiness 0 ;at their birth,consumers all have the same happiness' level ] end to go if cycle_# mod 10 = 0 [ ; asks the simulation to do the following procedure every 10 cycles until its closing bracket ask consumers ;; this procedure creates for each consumer four price lists, based on their maximum price(see slider), [ ; and sorts them from the highest to the lowest. set happiness 0 set price_list1 n-values quantity [ random-float price_ma ] set price_list1 sort-by [?1 > ?2] price_list1 set price_list2 n-values quantity [ random-float price_ma ] set price_list2 sort-by [?1 > ?2] price_list2 set price_list3 n-values quantity [ random-float price_ma ] set price_list3 sort-by [?1 > ?2] price_list3 set price_list4 n-values quantity [ random-float price_ma ] set price_list4 sort-by [?1 > ?2] price_list4 ] build_demand_curve? ask consumers-on patches with [pcolor = blue ] [without-interruption [foreach price_list1 ; rules to set happiness: [if ? >= price1 [set happiness (happiness + 1 ) ] ; everytime a consumer buys, his happiness ]]] ; increases of one unit. ask consumers-on patches with [pcolor = pink ] [without-interruption [foreach price_list2 [if ? >= price2 [set happiness (happiness + 1 ) ] ]]] ask consumers-on patches with [pcolor = red ] [without-interruption [foreach price_list3 [if ? >= price3 [set happiness (happiness + 1 ) ] ]]] ask consumers-on patches with [pcolor = green ] [without-interruption [foreach price_list4 [if ? >= price4 [set happiness (happiness + 1 ) ] ]]] ask consumers-on patches with [pcolor != white] ;; this procedures rules consumers'steps. [fd quantity - happiness] ask consumers-on patches with [pcolor = white] [wait 1 fd 10] ] ;; this bracket closes the one opened to list the operations to do every ten cycles set cycle_# cycle_# + 1 report-sold_quantities_firm? end ; closes procedure "to go" to build_demand_curve? ; this is the procedure to build the four demand curves set whole_price_list1 [] foreach n-values consumer_number [?] [set whole_price_list1 sentence whole_price_list1 price_list1-of consumer ? ] set whole_price_list1 sort-by [?1 > ?2] whole_price_list1 set whole_price_list2 [] foreach n-values consumer_number [?] [set whole_price_list2 sentence whole_price_list2 price_list2-of consumer ? ] set whole_price_list2 sort-by [?1 > ?2] whole_price_list2 set whole_price_list3 [] foreach n-values consumer_number [?] [set whole_price_list3 sentence whole_price_list3 price_list3-of consumer ? ] set whole_price_list3 sort-by [?1 > ?2] whole_price_list3 set whole_price_list4 [] foreach n-values consumer_number [?] [set whole_price_list4 sentence whole_price_list4 price_list4-of consumer ? ] set whole_price_list4 sort-by [?1 > ?2] whole_price_list4 plot_demand_curve? plot_sold_quantities end to plot_demand_curve? ; plots the four demands curves into one graph set-current-plot "demand curves" set-current-plot-pen "demand c1" plot-pen-reset foreach n-values (length whole_price_list1) [?] [plotxy (? + 1) (item ? whole_price_list1)] set-current-plot-pen "demand c2" plot-pen-reset foreach n-values (length whole_price_list2) [?] [plotxy (? + 1) (item ? whole_price_list2)] set-current-plot-pen "demand c3" plot-pen-reset foreach n-values (length whole_price_list3) [?] [plotxy (? + 1) (item ? whole_price_list3)] set-current-plot-pen "demand c4" plot-pen-reset foreach n-values (length whole_price_list4) [?] [plotxy (? + 1) (item ? whole_price_list4)] end to report-sold_quantities_firm? ; procedure to count how many items have been sold by the different firms ask consumers-on patches with [pcolor = blue] [without-interruption [foreach price_list1 [if ? > price1 [ set sold_quantities_firm1 sold_quantities_firm1 + 1 ]]]] ask consumers-on patches with [pcolor = pink] [without-interruption [foreach price_list2 [if ? > price2 [ set sold_quantities_firm2 sold_quantities_firm2 + 1 ]]]] ask consumers-on patches with [pcolor = red] [without-interruption [foreach price_list3 [if ? > price3 [ set sold_quantities_firm3 sold_quantities_firm3 + 1 ]]]] ask consumers-on patches with [pcolor = green] [without-interruption [foreach price_list4 [if ? > price4 [ set sold_quantities_firm4 sold_quantities_firm4 + 1 ]]]] end to plot_sold_quantities ;; procedure to plot sold quantities in one graph set-current-plot "sold quantities" set-current-plot-pen "q1" plot (sold_quantities_firm1) set-current-plot "sold quantities" set-current-plot-pen "q2" plot (sold_quantities_firm2) set-current-plot "sold quantities" set-current-plot-pen "q3" plot (sold_quantities_firm3) set-current-plot "sold quantities" set-current-plot-pen "q4" plot (sold_quantities_firm4) end to shock ; procedure assigned to the bottom that gives prices one shock set price1 price1 * 3 set price2 price2 * 3 set price3 price3 * 3 set price4 price4 * 3 end @#$#@#$#@ GRAPHICS-WINDOW 192 10 602 441 17 17 11.43 1 10 1 1 1 0 1 1 1 -17 17 -17 17 CC-WINDOW 5 541 1000 636 Command Center 0 SLIDER 0 10 172 43 consumer_number consumer_number 2 100 49 1 1 NIL BUTTON 9 269 99 311 NIL setup NIL 1 T OBSERVER T NIL SLIDER 0 75 172 108 n_quantity n_quantity 0 20 12 1 1 NIL SLIDER 0 42 172 75 price_ma price_ma 1 26 21 1 1 NIL MONITOR 6 412 63 461 NIL cycle_# 3 1 MONITOR 1 478 132 527 NIL sold_quantities_firm1 3 1 MONITOR 132 478 263 527 NIL sold_quantities_firm2\n 3 1 MONITOR 262 478 393 527 NIL sold_quantities_firm3\n 3 1 MONITOR 393 478 524 527 NIL sold_quantities_firm4 3 1 PLOT 612 10 990 258 demand curves NIL NIL 0.0 10.0 0.0 10.0 true true PENS "demand c1" 1.0 0 -13345367 true "demand c2" 1.0 0 -2064490 true "demand c3" 1.0 0 -2674135 true "demand c4" 1.0 0 -10899396 true SLIDER 1 131 173 164 p1 p1 5 20 15 1 1 NIL SLIDER 1 163 173 196 p2 p2 5 20 15 1 1 NIL SLIDER 1 195 173 228 p3 p3 5 20 15 1 1 NIL SLIDER 1 228 173 261 p4 p4 5 20 15 1 1 NIL BUTTON 86 421 184 454 Shock_offer shock NIL 1 T PATCH T NIL BUTTON 12 320 101 358 NIL go T 1 T OBSERVER T NIL PLOT 612 259 991 486 sold quantities price1 NIL 0.0 50.0 0.0 10.0 true true PENS "q1" 1.0 0 -13345367 true "q2" 1.0 0 -2064490 true "q3" 1.0 0 -2674135 true "q4" 1.0 0 -10899396 true @#$#@#$#@ WHAT IS IT? ----------- This model tries to explain the theoretical model of “monopolistic competition“ with a simple and easy understanding simulation model. The world is divided into four firms and a non-consumption area surrounding them; consumers move around according to specific rules linked to their level of happiness and decide whether to buy products or not. HOW IT WORKS ------------ Consumers move across the world onto the four firms according to their happiness. Consumers'happiness is determined according to how much they are able to buy: if a consumer can buy everything he planned to, he will be happy, if he can not buy anything he will be unhappy. In the intermediate cases, the rule of happiness is defined by the proportion of the level of happiness. They will move a lot if they are unhappy, and stay if they are happy. In the intermediate cases they will move inversely proportional to their level of happiness. Every agent on a patch with the representative colour of the firm is buying the firm's product. If a consumer cannot buy anything from that firm, will move to another one and will try to buy again. This happens in every cycle. If a consumer reaches the non-consumption area, he will stop for a second and then start running again. HOW TO USE IT ------------- The observer chooses the number of consumers using the slider on the interface. In the same way, the observer is asked to set quantity, firms’ prices and the maximum price the consumers are willing and able to pay for the products. To set the world for the simulation the observer has to click on the button “setup”. The world is generated, the patches take the four colours of the firms and the white colour for the non-consumption area and the consumers stand in a circle in the middle of the world. The simulation starts when the “go” button is clicked. During the simulation the observer can give prices a shock by clicking the “shock offer” button. On the interface observer can check the quantities sold by each firm and the number of cycles that has elapsed. The “demand curve” graph shows how the demand curves change over time, the “sold quantities” one shows the sold quantities dynamic over the whole simulation period. THINGS TO NOTICE ---------------- When the shock button is clicked, no consumers will buy anymore unless the reserve price is still higher than those of the firms. The firms with higher prices then price_ma will lose consumers and will stop selling products. It could also get empty. Looking at the “sold quantities” graph observer can notice that once he gives prices the shock, curves could get flat. THINGS TO TRY ------------- It could be interesting to try varying the level of the sliders on the interface and notice what happens. EXTENDING THE MODEL ------------------- The model can be extended by introducing other firms and other variables that can affect consumers behaviours. Another improvements can be to consider returns and marginal costs in making the model more sophisticated and accurate. RELATED MODELS -------------- This simulation has been inspired by the “ Monopoly “ model, by Pietro Terna. CREDITS AND REFERENCES ---------------------- This model has been created after attending the course “Informatica e simulazione per l’economia”, held by Professor Pietro Terna, at the Faculty of Economics, University of Turin. @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 link true 0 Line -7500403 true 150 0 150 300 link direction true 0 Line -7500403 true 150 150 30 225 Line -7500403 true 150 150 270 225 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 butterfly true 0 Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240 Polygon -7500403 true true 150 165 89 198 75 225 75 255 105 270 135 255 150 240 Polygon -7500403 true true 139 148 100 105 55 90 25 90 10 105 10 135 25 180 40 195 85 194 139 163 Polygon -7500403 true true 162 150 200 105 245 90 275 90 290 105 290 135 275 180 260 195 215 195 162 165 Polygon -16777216 true false 150 255 135 225 120 150 135 120 150 105 165 120 180 150 165 225 Circle -16777216 true false 135 90 30 Line -16777216 false 150 105 195 60 Line -16777216 false 150 105 105 60 car false 0 Polygon -7500403 true true 300 180 279 164 261 144 240 135 226 132 213 106 203 84 185 63 159 50 135 50 75 60 0 150 0 165 0 225 300 225 300 180 Circle -16777216 true false 180 180 90 Circle -16777216 true false 30 180 90 Polygon -16777216 true false 162 80 132 78 134 135 209 135 194 105 189 96 180 89 Circle -7500403 true true 47 195 58 Circle -7500403 true true 195 195 58 circle false 0 Circle -7500403 true true 0 0 300 circle 2 false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 consumers false 0 Rectangle -6459832 true false 176 141 247 180 Circle -7500403 true true 110 5 80 Polygon -7500403 true true 102 90 117 195 87 285 102 300 132 300 147 225 162 300 192 300 207 285 177 195 192 90 Rectangle -7500403 true true 127 79 172 94 Polygon -7500403 true true 192 90 237 150 222 180 162 105 Polygon -7500403 true true 105 90 60 150 75 180 135 105 Rectangle -10899396 true false 175 145 185 152 Rectangle -6459832 true false 171 140 185 180 Circle -6459832 false false 170 100 76 cow false 0 Polygon -7500403 true true 200 193 197 249 179 249 177 196 166 187 140 189 93 191 78 179 72 211 49 209 48 181 37 149 25 120 25 89 45 72 103 84 179 75 198 76 252 64 272 81 293 103 285 121 255 121 242 118 224 167 Polygon -7500403 true true 73 210 86 251 62 249 48 208 Polygon -7500403 true true 25 114 16 195 9 204 23 213 25 200 39 123 cylinder false 0 Circle -7500403 true true 0 0 300 dot false 0 Circle -7500403 true true 90 90 120 face happy false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 255 90 239 62 213 47 191 67 179 90 203 109 218 150 225 192 218 210 203 227 181 251 194 236 217 212 240 face neutral false 0 Circle -7500403 true true 8 7 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Rectangle -16777216 true false 60 195 240 225 face sad false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183 fish false 0 Polygon -1 true false 44 131 21 87 15 86 0 120 15 150 0 180 13 214 20 212 45 166 Polygon -1 true false 135 195 119 235 95 218 76 210 46 204 60 165 Polygon -1 true false 75 45 83 77 71 103 86 114 166 78 135 60 Polygon -7500403 true true 30 136 151 77 226 81 280 119 292 146 292 160 287 170 270 195 195 210 151 212 30 166 Circle -16777216 true false 215 106 30 flag false 0 Rectangle -7500403 true true 60 15 75 300 Polygon -7500403 true true 90 150 270 90 90 30 Line -7500403 true 75 135 90 135 Line -7500403 true 75 45 90 45 flower false 0 Polygon -10899396 true false 135 120 165 165 180 210 180 240 150 300 165 300 195 240 195 195 165 135 Circle -7500403 true true 85 132 38 Circle -7500403 true true 130 147 38 Circle -7500403 true true 192 85 38 Circle -7500403 true true 85 40 38 Circle -7500403 true true 177 40 38 Circle -7500403 true true 177 132 38 Circle -7500403 true true 70 85 38 Circle -7500403 true true 130 25 38 Circle -7500403 true true 96 51 108 Circle -16777216 true false 113 68 74 Polygon -10899396 true false 189 233 219 188 249 173 279 188 234 218 Polygon -10899396 true false 180 255 150 210 105 210 75 240 135 240 house false 0 Rectangle -7500403 true true 45 120 255 285 Rectangle -16777216 true false 120 210 180 285 Polygon -7500403 true true 15 120 150 15 285 120 Line -16777216 false 30 120 270 120 leaf false 0 Polygon -7500403 true true 150 210 135 195 120 210 60 210 30 195 60 180 60 165 15 135 30 120 15 105 40 104 45 90 60 90 90 105 105 120 120 120 105 60 120 60 135 30 150 15 165 30 180 60 195 60 180 120 195 120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195 Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195 line true 0 Line -7500403 true 150 0 150 300 line half true 0 Line -7500403 true 150 0 150 150 pentagon false 0 Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120 plant false 0 Rectangle -7500403 true true 135 90 165 300 Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285 Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285 Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210 Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135 Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135 Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60 Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90 square false 0 Rectangle -7500403 true true 30 30 270 270 square 2 false 0 Rectangle -7500403 true true 30 30 270 270 Rectangle -16777216 true false 60 60 240 240 star false 0 Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108 target false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 Circle -7500403 true true 60 60 180 Circle -16777216 true false 90 90 120 Circle -7500403 true true 120 120 60 tree false 0 Circle -7500403 true true 118 3 94 Rectangle -6459832 true false 120 195 180 300 Circle -7500403 true true 65 21 108 Circle -7500403 true true 116 41 127 Circle -7500403 true true 45 90 120 Circle -7500403 true true 104 74 152 triangle false 0 Polygon -7500403 true true 150 30 15 255 285 255 triangle 2 false 0 Polygon -7500403 true true 150 30 15 255 285 255 Polygon -16777216 true false 151 99 225 223 75 224 truck false 0 Rectangle -7500403 true true 4 45 195 187 Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194 Rectangle -1 true false 195 60 195 105 Polygon -16777216 true false 238 112 252 141 219 141 218 112 Circle -16777216 true false 234 174 42 Rectangle -7500403 true true 181 185 214 194 Circle -16777216 true false 144 174 42 Circle -16777216 true false 24 174 42 Circle -7500403 false true 24 174 42 Circle -7500403 false true 144 174 42 Circle -7500403 false true 234 174 42 turtle true 0 Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210 Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105 Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105 Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87 Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210 Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99 wheel false 0 Circle -7500403 true true 3 3 294 Circle -16777216 true false 30 30 240 Line -7500403 true 150 285 150 15 Line -7500403 true 15 150 285 150 Circle -7500403 true true 120 120 60 Line -7500403 true 216 40 79 269 Line -7500403 true 40 84 269 221 Line -7500403 true 40 216 269 79 Line -7500403 true 84 40 221 269 x false 0 Polygon -7500403 true true 270 75 225 30 30 225 75 270 Polygon -7500403 true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 3.1.4 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ @#$#@#$#@