1. Composite Geocoding in ArcGIS
Heather Wolfe

2. Some Geocoding Basics
Geocoding matches input addresses and zip codes with geometry from reference shapfiles.
The tool used to accomplish this is called a locator.
Locators have various strengths and weaknesses and produce data matches of varying quality. Their results are QC’d differently.

3. The Classic Trade-Off
The classic trade-off in geocoding is accuracy vs. % matched.
Generally, the higher the percentage that you match, the lower the accuracy that you have overall. .

4. The Zone Restriction
A “zone restriction” in a locator allows for more accuracy in a locator by not permitting matches with an incorrect zip code.
This reduces errors related to two cities having the same street, but also rejects otherwise good addresses with an incorrect zip.

5. The One Address Locator
The One Address Locator uses “one address”, or one point per address, data.
Strength: Accuracy
Weakness: Reduced matching
You choose whether or not to have a zone restriction

10. The Street Locator
The street locator can match input data to street ranges or street intersections.
Strength: Increased matching and compensation for data input error.
Weakness: Accuracy
You choose whether or not to have a zone restriction.

13. The Composite Locator Actually not a locator
A device that permits use of multiple locators on the same data set
Locators listed in descending accuracy
Unmatched data is put into the next locator as input data.

14. Strengths & Weaknesses of the Composite
Speed
Able to handle large amounts of data
More results than from one locator alone
Weaknesses
Accuracy
Not able to use interactive match
Some good addresses may be rejected as unmatched

15. More Accurate Use of Composite

16. Less Accurate Use of Composite

17. The Composite-Like Structure
Within 1 geographic area
One Address with Zone
One Address Without Zone
US Streets with Zone
US Streets without Zone
Individually rematch, QC and then merge
Within Multiple Geographic areas
One Address With Zone composite
One Address Without Zone Composite
US Streets With Zone Composite
US Streets Without Zone Composite
Individually rematch, QC and then merge

18. Troubleshooting your Composite
Have you mapped your input fields?
Do all of your reference data files have the same projection?
Does your input field contain house number, street direction, street name and street type in one field?
Have you mapped your reference fields correctly?
Have you mapped your input address fields?