MapQuest's geocoder tries to find the most accurate data it can to find where your address is regardless of what api used: directions, search, data manager, or, yup, geocoding. Starting with the most accurate data set, it tries to find a match for your address and steps down through less accurate data until a match is found. If none of the data sets have a match for your address it will fall down to the default value of the least accurate data set - the center of the US is the default response for the country data set. While it tries to find fuzzy matches along the way, the geocoder will stop once it finds a good match. Results included in the response are ordered by both accuracy and confidence and the secret sauce puts them in an order we believe will be most helpful to the most applications. The first result should be the most trusted. The geocodeQualityCode will indicate both how accurate and how confident the result is.
For example: "My house, Denver, CO 80202" returns several ambiguous results.
Z1XXA - Denver, CO 80202, US - The geocoder found an exact match for the 5 digit zip code.
B1CAB - [4600 - 5199] Packing House Rd, Denver, CO 80216, US - The geocoder found a fair match for the street name in a block, an exact match for the city and state, and a good match for the zip code. This is the first of a few B1CABs from the 12/2016 data.
B1CCC - [1 - 99] Ivy House, West Monocacy, PA 19518, US - The geocoder found a pretty bad match for the street name for a block, city and state, and zip code. This is the last quality code group of the default matches in the 12/2016 data.
The B1CCC type data is probably useless in an application unless there is human, or AI(?), intervention. It may be useful if a conscious choice can be made for incorrect input or "good enough" scenarios. An application with no conscious interaction would probably just take the first/best result and run with it. The application could decide if the location is good enough by evaluating the result code and determining if it fits requirements for accuracy determined by the application design.
The geocoder gets you the best results it can for the given input with the data that it has. This allows you to decide if you like the result and how to continue with that result.
Happy Geocoding, mapping, routing, and searching!
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