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Allen C. Goodman and Thomas
G. Thibodeau
Understanding how metropolitan areas are partitioned into housing submarkets
is important for several reasons. First, assigning properties to housing
submarkets will likely increase the prediction accuracy of the models
that are used to measure house prices. Second, identifying within metropolitan
area housing submarket boundaries will enable researchers to better model
spatial and temporal variation in those prices. Third, an accurate assignment
of properties to submarkets will improve lenders and investors ability
to price the risk associated with financing homeownership. Finally, providing
submarket information to housing consumers will reduce search costs.
Analysts have examined numerous techniques for constructing housing submarkets.
Some analysts have used statistical clustering techniques to group small
geographic areas (e.g. census block groups, census tracts, zip code districts,
etc.) into housing submarkets while others have developed procedures that
explicitly model submarket boundaries. Goodman and Thibodeau (1998, 2002),
for example, identify housing submarket boundaries by applying the hierarchical
modeling technique to housing markets. This technique, first used by Byrk
and Radenbush to study education, assigns elementary school zones to housing
submarkets depending on whether neighborhood public school quality is
capitalized into area house prices.
An important question related to housing submarket construction is whether
geographic areas need to be spatially adjacent in order to be considered
the same submarket. Housing consumers do not necessarily limit their search
to spatially concentrated areas and may search similarly priced neighborhoods
located throughout a metropolitan area when making housing consumption
decisions. This paper examines two alternative procedures for assigning
census block groups to submarkets: one that combines adjacent census block
groups into areas with enough transactions to estimate the parameters
of a hedonic house price equation and a second that permits spatial discontinuities
in submarkets. The criterion used to evaluate the alternative techniques
is the accuracy of hedonic house price predictions. In addition, this
paper examines the stability of housing submarket boundaries over time.
The empirical research is conducted using data obtained from the Dallas
Central Appraisal District (DCAD). The DCAD provided information for every
parcel of real property in Dallas County. In addition, since 1983 the
DCAD has retained information on prior sales prices and sales dates for
every property in the DCAD area. As of January 1, 2003, there were approximately
500,000 single-family homes in the DCAD area and approximately 300,000
transactions during the 1983-2002 period.
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