Spatial implications associated with using Euclidean distance measurements and geographic centroid imputation in health care research.
OBJECTIVE
To determine the effect of using Euclidean measurements and zip-code centroid geo-imputation versus more precise spatial analytical techniques in health care research.


METHODS
Commercially insured members from a southeastern managed care organization.


METHODS
Distance from admitting inpatient facility to member's home and zip-code centroid (geographic placement) was compared using Euclidean straight-line and shortest-path drive distances (measurement technique).


METHODS
Administrative claims from October 2005 to September 2006.


RESULTS
Measurement technique had a greater impact on distance values compared with geographic placement. Drive distance from the geocoded address was highly correlated (r=0.99) with the Euclidean distance from the zip-code centroid.


CONCLUSIONS
Actual differences were relatively small. Researchers without capabilities to produce drive distance measurements and/or address geocoding techniques could rely on simple linear regressions to estimate correction factors with a high degree of confidence.
BlueCross BlueShield of Tennessee, Medical Informatics Department, Chattanooga, TN, USA. stephen_jones@bcbst.co
Stephen G
SG
Jones
Avery J
AJ
Ashby
Soyal R
SR
Momin
Allen
A
Naidoo
D001334:Automobile Driving; D040362:Geographic Information Systems / Q000706:statistics & numerical data*; D006268:Health Facilities; D006297:Health Services Accessibility; D006302:Health Services Research / Q000379:methods* / Q000706:statistics & numerical data; D006798:Housing; D015233:Models, Statistical; D011177:Postal Service / Q000706:statistics & numerical data; D012044:Regression Analysis; D014481:United States