title: Using geographic information systems to compare municipal, county, and commercial parks data.
abstract: BACKGROUND
  Parks are an integral part of a favorable built environment, and several studies have found a positive association between a favorable built environment and physical activity. Parks data are available to researchers from various sources; however, the accuracy of data sources in representing parks is unknown. This study compared secondary parks data obtained from a commercial vendor with data from municipal/county government records, all of which were verified by using Internet searches, telephone inquiries, or on-the-ground audits.
  
  
  METHODS
  We studied large metropolitan areas in 3 states: North Carolina (1,837 sq mi), Maryland (1,351 sq mi), and New York (260 sq mi). We collected information on park land area (shapefiles) from municipal/county governments from 2009 through 2012 and from a commercial source in 2010.
  
  
  RESULTS
  Commercial parks data did not include 31.1% (119/383, 20.3 sq mi) of North Carolina, 42.9% (187/436, 21.8 sq mi) of Maryland, and 71.7% (640/892, 13.5 sq mi) of New York parks that we found and verified from municipal/county sources. Municipal/county data did not include 15.7% (60/383, 9.9 sq mi) of North Carolina parks, 27.5% (120/436, 74.6) of Maryland parks, and 9.0% (80/892, 6.3 sq mi) of New York parks that we found and verified from commercial sources.
  
  
  CONCLUSIONS
  In this study, the combination of commercial and municipal/county data sources that were verified provided the most complete and accurate shapefile. The quality of secondary sources of parks data should be checked prior to use and, if needed, methods incorporated to improve the capture of parks.
authors.affiliation: Gillings School of Global Public Health, Department of Epidemiology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27514, USA. kelly_evenson@unc.edu
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
authors.forename: Fang
authors.initials: F
authors.lastname: Wen
mesh_terms: D003132:Commerce / Q000706:statistics & numerical data; D004779:Environment Design / Q000592:standards; D005260:Female; D040362:Geographic Information Systems / Q000706:statistics & numerical data*; D006801:Humans; D009111:Local Government; D008297:Male; D008396:Maryland; D009518:New York; D009657:North Carolina; D011633:Public Facilities / Q000191:economics / Q000706:statistics & numerical data*