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Geographic Analysis

The Center's staff geographers have accumulated particularly strong expertise in methods of spatial analysis and GIS techniques that support development of indicators of local and regional conditions and change, including population and housing trends.  An on-going GISAPR project to develop indicators of social, economic, and environmental equity for the six-county Portland-Vancouver metropolitan area - Regional Equity Atlas - is likely our most involved and multifaceted effort to date in applications of methods of geographic analysis.  The Center has produced maps from  many other locations in Oregon.  Take a look at the new Atlas of Oregon Lakes, currently being revised, updated and expanded, now available online.


Often, statistical units for which Census and other secondary data is available do not conform to the shape and boundaries of one's study area; in fact, a good number of commonly used geographies: neighborhoods, watersheds, buffers along highways or streams, - do not neatly fit into areas for which data is reported. In these instances, allocation of Census or other data to custom geographies is necessary; it is performed using dasymetric mapping, surface modeling, and other methods of areal interpolation.

Administrative records, such as building permits or birth records, represent a potentially rich source of information about current (post-Census) housing or, given a time lag, future schoolchildren. We apply several GIS techniques to achieve high rates of geocoding and address-matching of these data. Surface modeling of geocoded administrative records (events) is helpful for analysis and visualization of spatial trends, calculation of changes over time, and in instances when data confidentiality needs to be protected.

Linking disparate data sources, such as tax lot records from tax assessor's office and students' home addresses, can result in a unique database necessary to reliably model short-term local population change. Such database, first developed for Portland Public Schools and replicated in other school districts, provides Center's geographers with crucial information used in population and enrollment forecasts.

Determining population, housing and other characteristics of areas within a certain distance from a location: a bus stop, a school, or a proposed grocery store, - is a frequently requested task for locating a facility or site, for evaluation of effects of an activity on its zone of influence, and the like. Depending on the task we use GIS tools from simple buffers to street network analyses in vector and raster to establishing a service area(s) and allocate Census or other data to it.