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represent characteristics or needs of individuals. A discussion of some of the problems associated with measuring and analyzing the attributes of places follows.
Arbitrary Geographic Boundaries
Geographic boundaries created for measurement or administrative purposes can create misleading spatial patterns in geographic phenomena. Trying to place an external boundary around a study region can create two artificial effects in measurement and analysis. One is an “edge effect” created by ignoring interdependences that occur outside the bounded region. A second effect is the artificial shape imposed by the boundary. Shape can affect the measurement of spatial point patterns (e.g., reported crime locations) since these compare the points’ locations relative to area. For example, as spatial units become more elongated, point pattern statistics tend to report higher levels of clustering for the same point pattern within that unit (Fotheringham and Rogerson, 1993).
Shape relative to area can also affect the measurement of interactions (e.g., origin-destination flows) since these are often recorded only when they cross an artificial boundary. Information about shape and area can be exploited to more accurately estimate distances from travel surveys (Rogerson, 1990) or to locate traffic counters, travel survey stations, or traffic monitoring systems (Kirby, 1997).
The problem of defining “urbanized areas” provides a relevant example of geographic bounding problems. The U.S. Census defines urbanized areas as jurisdictions with 1,000 persons or more per square mile. Figure 3.1 illustrates U.S. Census urbanized area boundaries for a portion of the Rocky Mountain Front Range that includes Ft. Collins and Greely, Colorado. Purple lines indicate the urbanized area boundaries, red shading indicates urban land use, orange shading indicates suburban land use; and yellow shading indicates exurban land uses. As can be seen, the census definition of urbanized area is problematic. Similarly, urban livability indicators such as measures of sprawl often ignore interdependences and interactions with proximal (or nearby) rural areas (Theobald, 2001).
There are several strategies for resolving geographic boundary problems in measurement and analysis (see Griffith, 1983; Griffith and Amrhein, 1983; Martin, 1987; Wong and Fotheringham, 1990). A practical computational strategy is to use GIS tools to manipulate boundaries systematically and to conduct the measurement and analysis given these different boundaries. This provides a sensitivity analysis of the indicator with respect to boundary definitions. Without this type of sensitivity analysis, the reliability and robustness of place-based livability measures that rely on administrative boundaries are unclear.