Home
Help
Resources
Extensions
FAQ
NetLogo Publications
Donate

Models:
Library
Community
Modeling Commons

Beginners Interactive NetLogo Dictionary (BIND)
NetLogo Dictionary

User Manuals:
Web
Printable
Chinese
Czech
Farsi / Persian
Japanese
Spanish

## NetLogo User Community Models

# coinGame2

## WHAT IS IT?

Simulation of a bilateral coin game played pairwise by a set of turtles sitting on a plane. The vertical position reflects the actual wealth, the horizontal position the turtle's number. Currently playing pairs are pictured by a link.
Lorenz Curve, Gini Coefficient and a histogram show the distribution of wealth.
You can explore the effects of "the rich get richer" obscured by the misleading ergodic hypothesis in traditional economics and the benefits of cooperation cooperation induced by a form of wealth-tax.
Logic influenced by Ole Peters, LML, see:
https://ergodicityeconomics.files.wordpress.com/2018/06/ergodicity_economics.pdf

## HOW IT WORKS

A fraction "select-ratio" of turtles throw a coin pairwise at each tick, the bet is a fraction "transfer-ratio" of the minimum of the wealth of both turtles.
For the looser the bet is multiplied by "mult-tails" and then subtracted from his wealth.
For the winner the bet is multiplied by "mult-heads" and then added to his wealth.
After all pairs have thrown their coins and their wealth was transferred, some redistribution in the form of a wealth-tax may be applied: If "tax-factor" is > 0 and wealth is > "tax-limit" a wealth tax (wealth * tax-factor) is subtracted. Then the collected wealth tax is redistributed evenly to all turtles or to the poor turtles below tax-limit, depending on the switch "redist-all?".
So you can simulate the effects of cooperation thru risk-sharing between players.

## HOW TO USE IT

Use the sliders to control the number of turtles "anz-turtles" and the initial wealth "init-wealth".
If you switch "random-init-wealth?" to "off" each turtle receives the equal "init-wealth" wealth.
If you switch "random-init-wealth?" to "on" each turtle receives a random wealth between 1 and "init-wealth".
Set the fraction of the minimum wealth of both turtles "transfer-ratio" to bet and the fraction of all turtles to play in one tick "selection-ratio".
Set the multiplicative factors "mult-heads", "mult-tails" (default: 1.0) to be applied to the transfer of the bet.
Optional set a "tax-factor", "tax-limit", and "redist-all?"
If you want bancrupt turtles to die, set "turtles-die?" to on, then press "setup".
To play one round press "go-1", to play as long as you wish, press "go".

## THINGS TO NOTICE

You see all turtles sitting on the black world area. The vertical position reflects the actual wealth, the horizontal position the turtle's number. Each turtle will go up or down vertically dependent of its current wealth after each tick.
Each pair of turtles (link) engaged in throwing a coin is connected by a line.
In the wealth-plot you see min, max, mean and median of the turtles wealth on a log10 scale.
In the wealth-distribution histogramm you see the number of turtles in different classes of wealth.
In the Lorenz Plot you see the actual shape of the Lorenz Curve.
In the Gini Plot you see the value of the Gini Coefficient over time.

## THINGS TO TRY

Try different values for multiplicative growth ("heads-mult", "tails-mult"),
Compare the wealth-distribution for no multiplicative growth (set both "heads-mult", "tails-mult" to 1.0) to other values of multiplicative growth (eg. 0.6, 1.5)
Try different "tax-factor"s and "tax-limits", switch "redist-all?" on/off.
What effects can you see in the histogram, Gini Plot and Lorenz Curve?

## EXTENDING THE MODEL

better visualization ideas?

## NETLOGO FEATURES

using turtle world to show turtle ranking by position,
histogram on varying upper and lower bounds

## RELATED MODELS

## CREDITS AND REFERENCES

Author: Rupert Nagler, Jan 2020, nagler@idi.co.at