Table 1.

Statistics of the prediction performance

Class	Statistics		Input
		Chemical	True	Predicted
		structure	pharmacological	pharmacological
		similarity	similarity	similarity
Enzyme	AUC	0.821	0.892	0.845
	Sensitivity	0.239	0.356	0.245
	Specificity	0.993	0.995	0.993
	PPV	0.358	0.527	0.369
Ion	AUC	0.692	0.812	0.731
channel	Sensitivity	0.134	0.137	0.142
	Specificity	0.996	0.996	0.997
	PPV	0.704	0.714	0.742
GPCR	AUC	0.811	0.827	0.812
	Sensitivity	0.147	0.172	0.164
	Specificity	0.994	0.996	0.995
	PPV	0.519	0.614	0.581
Nuclear	AUC	0.814	0.835	0.830
receptor	Sensitivity	0.067	0.057	0.077
	Specificity	0.995	0.994	0.996
	PPV	0.560	0.480	0.640

The AUC (ROC score) is the area under the ROC, normalized to 1 for a perfect inference and 0.5 for a random inference. The sensitivity is defined as TP/(TP+FN), the specificity is defined as TN/(TN+FP) and the PPV (positive predictive value) is defined as TP/(TP+FP), where TP, FP, TN, FN are the number of true positives, false positives, true negatives and false negatives, respectively.