Anna Giolitti, Francesco Mangiardi, Patrizia Mecozzi, Rosangela Sellitti

Computer Science and Simulation for Economics

Project work on

"Sector growth."


The applet requires Java 1.4.1 or higher. It will not run on Windows 95 or Mac OS 8 or 9. Mac users must have OS X 10.2.6 or higher and use a browser that supports Java 1.4. (Safari works, IE does not. Mac OS X comes with Safari. Open Safari and set it as your default web browser under Safari/Preferences/General.) On other operating systems, you may obtain the latest Java plugin from Sun's Java site.

created with NetLogo

view/download model file: sector_growth.nlogo


This model simulates the interaction between workers/unemployers and four macrosectors. Our patches are the macrosectors that have a different colour, a different variation of productivity (chosen by operators) and a random demand variation. Our turtles are the workers/unemployers: they assume the color of sector where they are working or the white one if they don't work and have as value of our wage, which corresponds to that of their own macrosector. The report workers-firms consists of workers' movements among sectors, that give firms'development or decline.


During their movement, workers can touch a macrosector and can be hired. The rules of hiring are: if the variation of productivity of the sector is inferior to the variation of demand and if the wage is inferior to that offered by the new sector. The workers come in the sector and they change their color, their number of identity and their level of wage.
Moreover, firms can also fire workers and this happens if its own variation of productivity is major of the variation of demand and, obviously, if they have workers inside.
Unemployers accept every work offered by firms: if the first firm they touch is ready to hire, they become its workers (and change color, number and wage).


In this model the operator can modify a three variables:
- with the slider POPULATION, it is possible to change the number of agents from 5 to 150 (the number of workers in each sector and the number of unemployers are the same: in fact the total number chosen by the operator is divided for 5);
- with the slider WAGE_SECTOR it is possible modify the level of the wage offered by the sector;
- with the slider TRIP the operator can decide the number of cycle of variation of demand. It can vary from a minimum of 200 to a maximum of 5000 cycles, with an increasing of 200. There is, moreover, a monitor CLOCK, wich count a number of cycles and take value zero when it reach the number decided by the slider TRIP;
- With the chooser VARIATION_ PRODUCTIVITYSECTOR the operator can vary the productivity for each sector. The operator can choose only five values: -100, -50, 0, 50, 100.

Differently, the variation of the demand is a random and it can't be chosen by operator.
Its range of variability is -150 /150. The operator chooses, with the slider TRIP, how many cycles its value change.

With the SETUP button the world in which the agents interact is created, like also the values for the variables of patches ( number of identification, position, colour, variation of productivity, wage offered by sector)and turtles (number of sector, position, colour and wage). In particular, at the beginning workers start from the center of the relative sector, while unemployers are in the center of the world. Furthermore, these last are of white colour, workers take the same colour of their own patch, but with different degree.

With the STEP buttom, the world starts to fuction: workers and unemployers move random and when they touch macrosector, the interaction starts (hiring and dismissing).

There are five graphics that represent some important dynamic that take place during the simulation. They allow us to know as the number of workers for each patch and the number of unemployers change during the simulation. To see clearly the total number of agents, we have created five monitors to count workers and unemployers.


It is preferable that the operator chooses a huge level of cycles in wich the variation of demand is costant (TRIP). This allows to create an interaction turtles-patches more realistic.


The operator can modify different variables: population, variation of productivity and the level of wage offered by sectors how many times the variation of demand change, but not its value taht is random.
To evaluate different scenaries he should choose different values of wage offered by the sector and the different values for the variation of productivity.
It's interesting modify these values during the simulation.In this way it's possible to show what it happens when there are sectors in expansion or in decline.Finally, the operator can select an elevated number of agents to make the model more dynamic.


To make the model more detailed the user can:
- add new rules for hiring and dismissing,
- create more properties for turtles (skills, age, exc...) and patches (production, technology, exc...),
- to establish a maximum and minimum level of workers for sector.


The rules used in the simulation refers to the book:
P. Frigero "Economia Applicata".
On the web it’s possibile to find one NetLogo model which we have used as a reference:
“Population mobility in Italy” by Claudio Patrucco, Domenico Scarlato