Accuracy of residential geocoding in the Agricultural Health Study

Table 2 Accuracy of crop exposure classification for Agricultural Health Study addresses in 14 counties in Iowa by geo-location data source, overall and by rural status

		Sensitivity		Specificity		OR_obs^b
>0 Acres of crop within specified distance from home	Prevalence (%)^a	Address-matched	E911	Address-matched	E911	Address-matched	E911
Overall
Corn
250 m	97.6	99.5	99.7	82.8	91.0	1.67	1.79
500 m	99.8	99.9	100.0	88.9	88.9	1.47	2.00
Soybean
250 m	85.7	97.4	98.7	89.5	95.3	1.73	1.85
500 m	97.1	99.6	99.8	92.5	97.9	1.77	1.88
Alfalfa/hay
250 m	55.7	84.9	95.4	88.8	95.8	1.62	1.86
500 m	78.5	94.8	98.9	81.9	95.2	1.64	1.91
Other row crops
250 m	68.9	89.5	97.1	87.2	94.6	1.60	1.86
500 m	87.6	97.8	99.3	88.0	93.9	1.72	1.90
Rural ^a
Corn
250 m	99.8	99.9	99.9	28.6	85.7	1.22	1.46
500 m	100.0	100.0	100.0	0^±	0^±	-	-
Soybean
250 m	98.3	99.2	99.6	52.7	83.6	1.36	1.64
500 m	99.9	100.0	100.0	0^±	50.0	-	-
Alfalfa/hay
250 m	56.2	80.5	94.4	86.9	95.5	1.54	1.84
500 m	74.1	92.5	98.6	79.3	94.7	1.59	1.90
Other row crops
250 m	78.2	88.4	97.0	79.6	92.2	1.44	1.79
500 m	89.8	97.4	99.5	84.0	92.3	1.63	1.91
Non-rural ^a
Corn
250 m	93.5	98.7	99.3	86.1	91.3	1.69	1.81
500 m	99.6	99.8	100.0	100.0	100.0	1.50	2.00
Soybean
250 m	62.2	92.2	96.2	92.5	96.3	1.74	1.86
500 m	91.9	99.0	99.4	93.8	98.6	1.80	1.88
Alfalfa/hay
250 m	54.7	93.2	97.2	92.4	96.4	1.78	1.91
500 m	86.7	98.6	99.3	91.1	97.0	1.80	1.91
Other row crops
250 m	51.6	92.4	97.3	93.6	96.6	1.80	1.91
500 m	83.7	98.6	99.0	92.7	95.8	1.85	1.89

^±Specificity = 0 because there were no unexposed addresses.
^aPrevalence of crops near addresses and rural status were based on rooftop locations.
^bWhere OR_true =2.0.

ISSN: 1476-072X