Table 3.

Implantable Doppler monitoring data.

Normal on Doppler (negative)		Abnormal on Doppler (positive)
34		6
No thrombosis	Thrombosis	No thrombosis	Thrombosis
34	0	2	4
TN	FN	FP	TP
Sensitivity = TP/TP+FN = 4/4 = 100%
Specificity = TN/TN+FP = 34/36 = 94.44%
PPV = TP/TP+FP = 4/6 = 66.66%
NPV = TN/TN+FN = 34/34 = 100%
Accuracy (efficacy) = TP+TN/TP+TN+FP+FN = 38/40 = 95%

FN, false negative; FP, false positive; NPV, negative predictive value; PPV, positive predictive value; TN, true negative; TP, true positive.