For the unbiased calculation of a measure in a different context see: http://users.nber.org/~edegan/w/images/d/d0/Hall_(2005)_-_A_Note_On_The_Bias_In_Herfindahl_Type_Measures_Based_On_Count_Data.pdf
===GIS Resources===
*https://www.census.gov/geo/maps-data/data/tiger-line.html
*https://www.census.gov/geo/maps-data/data/tiger.html
*http://postgis.net/features/
*https://en.wikipedia.org/wiki/GIS_file_formats