. 2017 Mar 16;12(3):e0173945. doi: 10.1371/journal.pone.0173945

Table 2. Values of accuracy of the questionnaire.

Best scenario^a	Sensitivity % (95% CI)	Specificity % (95% CI)	PPV % (95% CI)	NPV % (95% CI)	TP	FP	TN^c	FN^c
Three-stage design	76.3 (59.8–88.6)	99.6 (99.4–99.8)	69.0 (52.9–82.4)	99.7 (99.5–99.9)	29	13	3511	9
Worst scenario^b	Sensitivity % (95% CI)	Specificity % (95% CI)	PPV % (95% CI)	NPV % (95% CI)	TP	FP	TN^c	FN^c
Three-stage design	58.0 (43.2–71.8)	99.6 (99.4–99.8)	69.0 (52.9–82.4)	99.4 (99.1–99.6)	29	13	3499	21

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

^a False negative (n = 9) have been estimated on the basis of the sample proportion (0.3%).

^b False negative (n = 21) have been estimated on the basis of the upper limit of the 95% CI of the sample proportion (0.6%).

^c expected values.