190 likes | 199 Views
Learn about geocoding for neighborhood research, options available including U.S. Census Geocoder, SAS Proc Geocode, ArcGIS Online, and more. Understand how to choose the best geocoder for your project based on address data, budget, and accuracy needs.
E N D
What is Geocoding? • Geocoding uses a description of a location, most typically a postal address or place name, to find geographic coordinates from spatial reference data such as building polygons, land parcels, street addresses, postal codes, etc.
What Happened? • Geocoding used to be easy! • ESRI switched from unlimited geocoding to pay-per-search geocoding • Bulk geocoding became expensive for many users • Special thanks to Eric Burnstein for testing and reporting on current geocoding options • Before: • Now:
What Options are Available? • We tested a number of geocoding services. The best option will depend on the specific needs of the research project. • U.S. Census Geocoder • Smarty Streets • ArcGIS Online • Semaphore ZP4 • Texas A&M Geoservices • SAS Proc Geocode • Google/Bing/Mapquest API • Local Geocoders (ie. Washington,DC MAR geocoder)
Which is Best for Me? • To assess the geocoding options, first answer the following questions… • How many addresses do I need to geocode? • What is the quality of my address data? • Are the addresses limited to one city? State? The entire U.S.? • Are the addresses mostly in Metro areas? Rural areas? • How precise do I need the final output? • How much project money is budgeted for geocoding? • What is the end-goal (appending Census data, mapping for the web, etc.)?
Choosing a Geocoder • Census Geocoder • Are the addressesall local? • Over or under 1,000 records? • No • Under • Over • Yes • Does the project have budget for Geocoding? • Local Geocoder • SAS Proc Geocode • No • Yes • Need to find unmatched addresses? • Desired accuracy of results • Standard • Texas A&M Geoservices • Yes • High • ArcGIS Online
ArcGIS Online • Best use: Project with sufficient budget that requires high level of accuracy. • Pros: • Most accurate option • Fast processing • Cons: • Expensive and difficult credit system • Higher learning curve than alternatives
U.S. Census Geocoder • Best use: Project with a small number of addresses and a tight budget. • Pros: • Completely free • Easy to use • Cons: • Limited to 1,000 addresses • Lower accuracy than alternatives
SAS Proc Geocode • Best use: Project with a large number of addresses and a tight budget. • Pros: • Free (inside UI) • Handles unlimited addresses • Cons: • Basic knowledge of SAS required • Lower accuracy than alternatives
Texas A&M Geoservices • Best use: Project with sufficient budget that requires high level of accuracy and limited time to set-up and learn ArcGIS online. • Pros: • Easy to use • Reasonable cost • Cons: • Slower than the alternatives • Not the cheapest or the most accurate
Local Geocoders • Best use: Project uses addresses for only one city. • Pros: • Highly accurate • Usually free to use • Cons: • Limited to a single city • Need to learn a new tool for each city
Google/Bing/Mapquest API • Best use: Project with good quality address data, no or low budget. • Pros: • Can use Stata. R, and other tools • Many are already be familiar withthese services • Cons: • Limited free queries per IP per day • Less transparent on quality of matches • Enterprise API key is expensive
Other Options (not generally recommended) Semaphore ZP4
Hybrid Geocoding Approaches • 50,000 addresses • 10,000 unsuccessful geocodes • 40,000 successful geocodes • 5,000 successful geocodes • 45,000 successful geocodes
Questions? Please ask now or email me! rpitingolo@urban.org