Table 1.

Standard 2 × 2 contingency table depicting possible outcomes of a binary classification test.

		Actual Status
		Disease Positive	Disease Negative
Assignment Status	Test Positive	TP	FP	PPV =TP/(TP + FP)
	Test Negative	FN	TN	NPV =TN/(TN + FN)
		Sensitivity =TP/(TP + FN)	Specificity =TN/(TN + FP)

Note: Abbreviations—FN, false negative; FP, false positive; NPV, negative predictive value; PPV, positive predictive value; TN, true negative; TP, true positive.