The purpose of address matching is to:
find the location of an event which has been recorded at a street address; and to
identify the political and administrative areas to which it belongs.
Address-matched locations are usually recorded as unique latitude and longitude coordinates. Addresses are linked to geographic areas recognized and coded by the U.S. Census. Political and administrative areas in the U.S. recognized by the U.S. are townships, counties, census tracts, census block groups, census blocks, and school districts.
One file is a digital street map which describes the locational coordinates of the centerline of all streets, the range of street addresses that are found on each street segment, and the different political and administrative areas to which each side of each street line segment belongs.
The U.S. Census Bureau has developed TIGER line files to describe the street centerline map of the U.S. and Census Geography. Although far from perfectly accurate, these files are periodically revised and updated by the Census Bureau. Many private firms offer value-added services including improved TIGER files or address-matching services.
The second file contains the street address descriptions of the events which are to be address-matched.
Address-matching is rarely a fully automated, computerized process. People who intend to address-match their data or to use the results of address-matching processes should know the typical problems that are likely to occur in this process, the different ways in which users can deal with these problems and the effect of these problems on the quality and reliability of results.
An address may not address-match because it is not compatible with the digital street map. This can happen because of inaccuracies or inconsistencies in the digital street map or because of inaccuracies or inconsistencies in the file of addresses to be matched.
Address-matching rates (the proportion of addresses that are correctly matched) will increase if efforts are made to increase the quality of the digital street map, the address file, or both.
There are special-purpose address-matching computer software programs that come with their own digital map data, and there is more general GIS software that includes address-matching functions.
Comparing the performance of different computer packages is difficult because each defines "an address-match" slightly differently and their relative performances may vary from one region to another. Many systems tolerate small differences in elements of the match. Often, the user can decide the required degree of exactness before accepting the match.
Daniel and Slezak (1995) used a classification of "strict," "moderate," and "lenient" address-matching criteria in comparing five commercial address-matching software systems that ranged in price from $2,690 to $28,000.
Daniel, L. and Slezak, J. "Street talk: the word on address-matching." Business Geographics, April, 1995, pp. 26-33.