Diagnostic test indicators.

Table 2: Diagnostic test indicators.

Test Indicator	Formula
Sensitivity	$S e n s i t i v i t y = \frac{a}{a + c}$
Specificity	$S p e c i f i c i t y = \frac{d}{d + b}$
False Positive Rate	$F a l s e P o s i t i v e R a t e = \frac{b}{b + d}$
False Negative Rate	$F a l s e N e g a t i v e R a t e = \frac{c}{c + a}$
Accuracy	$A c c u r a c y = \frac{a + d}{a + b + c + d}$
PPV (Positive Predictive Value)	$P P V = \frac{a}{a + b}$
NPV (Negative Predictive Value)	$N P V = \frac{d}{c + d}$
PLR (Positive Likelihood Ratio)	$L R + = \frac{S e n s i t i v i t y}{1 - S p e c i f i c i t y}$
NLR (Negative Likelihood Ratio)	$L R - = \frac{1 - S e n s i t i v i t y}{S p e c i f i c i t y}$
OR (Odds Ratio)	$D O R = \frac{\frac{S e n s i t i v i t y}{1 - S e n s i t i v i t y}}{\frac{1 - S p e c i f i c i t y}{S p e c i f i c i t y}}$
YI (Youden Index)	YI = Sensitivity + Specificity - 1