The processes modeled in the SimSeg Lite simulation are
governed by the settings of different model parameters.
The values assigned to the model's parameters define the
"scenario" for a simulation experiment; they determine the
specific conditions of that simulation experiment.
The values of many parameters can be set and manipulated by
the user. Thus, the user can specify the "scenario" (i.e.,
the conditions) for the experiment.
The model has both fixed and variable parameters. Fixed
parameters are "hard coded" into the program; the user
cannot change them. Variable parameters may be set by the
user (within specified ranges). The major fixed and
variable parameters are described below.
City Size: The city has 177 neighborhoods arranged in an
15x15 grid. Each neighborhood has 25 housing units. In all there
are 4,425 housing units.
Cycle/Time. Simulations progress in "cycles" - the time dimension ofthe
simulation. Cycles are defined in terms of activity
(specifically, housing search activity), not
actual elapsed time. The user may set the number of
cycles to be completed.
Search. During each cycle, 25% of households are randomly
selected and permitted to search for housing. During a
search, the searching household will examine and evaluate 12 randomly
chosen vacant housing units.
Evaluation. Searching households evaluate the housing
units they encounter during search. If one provides greater
residential satisfaction (relative to the households'
preferences) than the households current residence, the
household moves to that housing unit. Otherwise
the household remains in its current location.
Forced Moves. In 20% of searches, the household is
required to move even if they would prefer to stay in their
current housing unit. In this situation, the household moves to
the most desirable vacant housing unit it encountered, even
if that unit is less satisfying than the household's
current housing unit. This simulates demographic processes
that generate random vacancies in all neighborhoods of the
city (e.g., death of the household, the formation of new
households, job transfers, expiration of lease, change in
the size of the household, etc.).
Ethnic Preferences: Specification of group preferences for in-group and
out-group contact. These can be set separately for each group in the
simulation and thus can assume many different combinations.
Agent Vision: Households may define neighborhoods in a variety of
ways based on the setting of agent vision. Under some options,
households see a very small neighborhoods. Under other options, they
"see" a much larger neighborhood.
Ethnic Demography: The ethnic demography of the city can vary in
two ways. The city may consist of two groups (Whites and Blacks)
or three groups (Whites, Blacks, and Hispanics). And the sizes of
the groups may vary based on the setting for Black and Hispanics
(in the three group specification).