I set up Tiger Geocoder in PostGIS on my local box (PostGIS 2.1.3, PostgreSQL 9.3.5, Tiger 2013 data).
The problem I'm running into is that on almost every street most of the points are clustered, with only a few addresses in their correct locations. You can see an example in the image below:
My first thought was that somehow I had set up the geocoder with the wrong SRID, but I did everything "by the book" and I have tried several times but I still get the same results.
Is this to be expected with Tiger data or am I doing something wrong?
Answer
The documentation you are referencing (see the proposed answer below) from the Census Bureau's site refers solely to the Landview 6 product (released in 2003).
The Census Bureau does not release information about specific addresses, including the exact location, due to Title 13 of the US Code. The TIGER/Line Shapefiles and the Census Geocoder documentation both include information about the publicly available address ranges.
The geocoder takes the address and determines the approximate location offset from the street centerline. An interpolated latitude/longitude coordinate is returned along with the address range the Census Bureau has on that stretch of road. That coordinate is then used to determine the geography that the address is within.
Q. What is the source of your address ranges?
A. The address ranges used in the geocoder are the same address ranges that can be found in the TIGER/Line Shapefiles which are derived from the Master Address File (MAF). The address ranges are potential address ranges, not actual address ranges. Potential ranges include the full range of possible structure numbers even though the actual structures might not exist. The majority of the address ranges we have are for residential areas. There are limited address ranges available in commercial areas. Our address ranges are regularly updated with the most current information we have available to us.
http://www.census.gov/geo/maps-data/data/geocoder.html
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