MABLE/Geocorr Applications Index Page

These geocorr web modules allow the user to obtain geographic correpondence files (aka "crosswalk files", "correlation lists", etc.) for dozens of geographic layers for the United States (50 states + DC). The various applications are nearly identical in what they do, but vary in terms of the vintage of the MABLE datbase being accessed.

Versions

  • Geocorr14, the current production version, works with available data through 2014.
  • Geocorr2k uses geography from the 2000 census (with some updated fields as recent as 2008).
  • Geocorr90 uses geography from the 1990 census. This is the original.

Documentation

  • Videos of 4 sample runs.. These examples were created circa 2010. They access the 2k version of MABLE/geocorr but the concepts still apply to any version.
  • The orginal help file.. Quite possibly the oldest living document on this web site. Originally written circa 1996 to document this new application. It is still the best resource to use when trying to understand how geocorr does what it does.
  • Sample queries 2012. These don't show and tell like the video modules do, but they take a lot less time to view and they can be easily used as templates to do your own queries. You should begin by following links to the htm files. See the Readme.html file for tips.
  • mable_geocorr12_2015. Powerpoint presentation on M/G at the 2015 Missouri GIS conference. 36 slides.
  • 2006 Power point. This 39-slide presentation is still useful.
  • Data Allocation Using Geographic Equivalency Files is a tutorial illustrating how geographic equivalency files can be used to allocate data summarized at one geographic level to another (source to target). For techies only.

Notes

  • Each of these geocorr versions has its own link to a MAGGOT file. The Master Area Geographic Glossary of Terms pages provide brief descriptions of the geographic layers available for that version of MABLE/geocorr. (The link appears just below the Select State(s) box on the geocorr form).
  • The MABLE databases are almost entirely based on the Census Bureau's TIGER databases. These do not exist prior to 1990 and so there is almost no chance that we shall ever see a geocorr80 or geocorr70. But a geocorr2020 is highly likely.
  • Each version of MABLE is based on its own set of census blocks (1990, 2000, or 2010). There is currently no version of geocorr that can work across these database to produce correlations across time. So, you can't use geocorr to create a tract-2000 to tract-2010 equivalency file.
  • When doing large extracts (usually this means when doing all states at once) use the Output Options section to turn off the report file output. Generating such large html files wastes time and space.
  • For techies only: The MABLE databases are collections of state-based SAS data sets that can be directly accessed using MCDC's Uexplore/Dexter modules. Each state has four SAS data files with [stab]v (e.g., alv, akv, ...) being a SAS view that merges the other three together to give you all the geocodes at the block level for that state. Dexter can provide output in SAS data set and DBF formats as well as CSV, HTML and PDF.