A probabilistic sampling method (PSM) for estimating geographic distance to health services when only the region of residence is known

Table 1 Measures of central tendency for estimated distances (in miles) between respondent locations and IPV service centers using three methods

	PSM (median)	PSM (mean)	ZCTA centroid as geocode†	ZIP Code population center as geocode
Range	0.39 - 66.4	0.53 - 65.6	0.09 - 67.2	0.00* - 66.6
Median	5.2	5.4	5.4	6.0
Mean (SD)	10.1 (11.2)	10.2 (11.2)	10.5 (11.1)	9.9 (11.2)
1^st Quartile	2.9	3.1	3.6	3.4
3^rd Quartile	12.2	12.3	12.1	11.7

The table compares distance estimates obtained using the Probabilistic Sampling Method (PSM), ZCTA centroid, and ZIP Code population center geocoding approaches (n = 1467). * The value of 0 reflects the distance (e.g., 0 miles) between the ZIP Code center point and itself when it is used as a geocode for both the subject's residence and the location of the IPV service center. † Some distances calculated using the ZCTA centroid as the geocode for the subject's residence reflect the distance between the ZCTA centroid and the ZIP Code center point, when IPV service centers were geocoded to ZIP Code centers.

ISSN: 1476-072X