Table 1. Model Prediction Metrics for the Validation Data set Used to Estimate Geogenic Lithium (Li) in Drinking-Water Supply Wells throughout the Conterminous United States.

Li classification	class 1 (≤4 μg/L)	class 2 (>4 to ≤10 μg/L)	class 3 (>10 to ≤30 μg/L)	class 4 (>30 μg/L)
sensitivity	0.8850	0.3333	0.6100	0.5580
specificity	0.7905	0.9188	0.8424	0.9548
balanced accuracy	0.8377	0.6261	0.7262	0.7564