Biology Reference
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the behavior choices made by individuals as he explored the causes of segregation
in a society which he perceived to not express outright racism [
10
,
11
]. Schelling's
model consists of a checkerboard, with each grid space representing a possible home.
The agents can be thought of as red and green turtles that fit onto a checkerboard grid,
and who are given an opportunity to move to a new grid space at each time step. The
turtle will choose to move if some proportion of its neighbors are not the same color
as itself. Schelling found that very low levels of personal preference can lead to the
global phenomenon of segregation. Schelling won the 2005 Nobel Prize in Economic
Sciences “for having enhanced our understanding of conflict and cooperation through
game-theoretic analysis,” an award which Schelling believes was at least in part due
to this work [
11
].
4.1.3.1
ABMModelingExercises:Segregation
We can experiment with Schelling's ideas using the NetLogoModels Library which is
located under the “File” directory in NetLogo. There, in the Social Sciences section,
we find the model “Segregation,” which is inspired by Schelling's work on housing
patterns in cities [
12
]. The model consists of green and red turtles who prefer to live
near their own kind. The model allows us to choose the number of turtles that we begin
with, as well as the percentage of like-turtles that need to be present to keep a turtle
from moving. The model reports the average percentage of same-color neighbors
for each turtle, as well as the percent of turtles who are forced into an “unhappy”
situation of too many turtle neighbors with differing colors. Open the Segregation
model, and familiarize yourself with the three tabs “Interface,” “Information,” and
“Procedures.” The “Interface” tab is where we run our simulations for this multicolor
turtle dilemma. The “Information” tab explains the model's assumptions and outputs.
Finally, the “Procedures” tab shows the code that generates the model. Let's begin by
exploring the model using the Interface tab.
Exercise 4.8.
Using the
number
slider, choose to start with 1000 turtles, and assume
that turtles will be happy if at least 20% of their neighbors are their same color by
setting the
%-similar-wanted
slider. Click the setup button, followed by the go
button.
a.
If this process is repeated three times, will the output change for the percent of
same-colored turtle neighbors?
b.
What percentage of turtles seem to be happy at the end of each simulation? (Note
that sliders should be set as stated in the exercise.)
c.
Did the end-proportion of numbers of like-colored turtle neighbors mirror the
minimum requirement for each turtle to be happy?
Exercise 4.9.
This exercise explores the effect of turtle density to the resulting seg-
regation. How do the output measures change as the number of turtles increases
and decreases on this fixed grid? Do not change the assumption of 20% as the
%-similar-wanted
.
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