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National Cancer Data Base - Data Dictionary PUF 2013

Distance Metrics

The PUF includes a "crow-fly" or great circle distance measure between the latitude and longitude of the centroid of patient's ZIP code of residence and the latitude and longitude of the facility mailing address. The precision of this item as an indicator of the true distance between two points is dependent upon the spatial area of the ZIP code and the proximity of the facility’s administrative mailing address to the actual treatment center. If facility level analyses of distance to treatment are conducted using this variable, researchers need to take into account whether the treatment occurred at the facility included in the PUF data, or at a facility not included in the PUF.