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Table 4 Distribution of positional error (meters) a of geocoded addresses in Iowa and North Carolina from two subcohorts within the Agricultural Health Study, overall and by rural status

From: Accuracy of residential geocoding in the Agricultural Health Study

     Positional Error (m)     
GPS vs. Address-Matched Geocode N % Min Mean SD Median (IQR) Max IQR Percent ≤100 m Percent ≥1000 m
Overall           
  Iowa 1917 73.1 1 348 1178 131 (65–287) 28556 222 39 4
  North Carolina 707 26.9 5 272 1189 99 (53–210) 20695 156 50 4
Rural b           
  Iowa 1583 82.6 6 406 1288 153 (84–344) 28556 260 30 5
  North Carolina 637 90.1 5 262 981 105 (57–218) 20695 161 48 4
Non-rural           
  Iowa 334 17.4 1 77 125 49 (29–82) 1673 53 81 0
  North Carolina 70 9.9 9 362 2362 55 (24–112) 19830 88 71 1
  1. aPositional error was determined by comparing global positioning system (GPS) coordinates taken at the entrance to the home to geocoded address coordinates using the NAVTEQ street database.
  2. bRural status was based on GPS location.