Simple Agents, Complex Emergent City: Agent-Based Modeling of Intraurban Migration - Computational Approaches for Urban Environments - page 120

6.1 Introduction

Intraurban migration, or residential moves within a metropolitan area, is a com-
plex process involving the interaction of housing market characteristics with the
perceptions of home searchers. Intraurban migration research has a long and rich
history in geography and other social sciences, engineering fields, and policy
disciplines (Dorigo and Tobler 1983 ;Clark 1986 ; Brown and Moore 1970 ; Roseman
1971 ; Simmons 1968 ; Simpson et al. 2008 ;Clark 2008 ). There remain significant
challenges in terms of data, method, and theory in understanding this form of
migration. Data on specific individuals who drive intraurban migration is difficult to
obtain and use. Methodologically, there is a need to combine the most common
approach, statistical methods, with fast-emerging simulation modeling methods.
In terms of theory, the large number of competing explanations for intraurban
migration points to the need for continuing work on foundational research on
individual behavior. When these challenges of data, method, and theory are taken
together, they indicate the need for empirically based approaches that combine
statistical and simulation models to develop and test straightforward frameworks
for understanding how individual behavior gives rise to aggregate patterns and
processes of intraurban migration.
We developed an agent-based model that draws on novel data derived from land
parcels to develop and test an updated form of the intervening opportunity theory of
intraurban migration. This work is significant in several respects. This conceptual
model brings together underexamined geographical and sociological findings to
develop and test straightforward spatial behavioral rules that capture key features
of intraurban migration. To specify and test this model we developed a new data
source, individual migration chains extracted from tax parcel data that allowed us
to track the movements of actual households in space and over time. We bring these
data and the conceptual model together in an agent-based model that is calibrated
and validated with mathematical and statistical approaches, leveraging the relative
strengths of these different methods. More broadly, this work addresses the need for
simple and generalizable to complement the large and growing body of work that
focuses on representing complicated dynamics with extensive and detailed datasets
(Brown et al. 2008 ; Torrens 2012 ). It also contributes to the fast expanding body
of work seeking to simplify complex urban dynamics by using new data sources to
develop relatively straightforward and generalized models that capture significant
features of urban form and processes (Batty 2008 , 2012 ).
The rest of this paper examines this confluence of data, method, and theory. The
next section reviews locational decision-making theories of intraurban migration
and proposes a model for housing location decisions with two different strategies.
Section 6.3 applies this model to intraurban migration of homeowners in the Twin
Cities Metropolitan Area of the USA (TCMA), along the way introducing the use
of land parcel data to calibrate and validate an agent-based model of individual
migration. Section 6.4 presents the model results, including model validation. The
paper concludes with discussion of our findings and their implications for urban
agent-based modeling and our understanding of intraurban migration generally.