Table 2.

Performance measures and their definitions.

Notation	Description	Upper Bound
Accuracy	(TP + TN)/(TP + FN + FP + TN)	1 when FN = 0 and FP = 0
Sensitivity (Recall, True positive rate)	TP/(TP + FN)	1 when FN = 0
Specificity (True negative rate)	TN/(FP + TN)	1 when FP = 0
Precision	TP/(TP + FP)	1 when FP = 0
Balanced classification rate	(SN × SP)1/2	1 when SN = 1 and SP = 1
F1-score	(2 × SN × Precision)/(SN + Precision)	1 when SN = 1 and Precision = 1

TP: true positive; TN: true negative; FP: false positive; FN: false negative; SN: sensitivity; and SP: specificity.