aDepartment of Microbiology, IMS & Sum Hospital Medical College, Siksha ‘O’ Anusandhan University, Kalinga Nagar, Bhubaneswar, Odisha, India.
bDepartment of Pharmacology, IMS & Sum Hospital Medical College, Siksha ‘O’ Anusandhan University, Kalinga Nagar, Bhubaneswar, Odisha, India.
cCentral Research Laboratory, IMS & Sum Hospital Medical College, Siksha ‘O’ Anusandhan University, Kalinga Nagar, Bhubaneswar 751003, Odisha, India.
Copyright ©2013, Korea Centers for Disease Control and Prevention
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Smear test results | Culture test results
| Total | |
---|---|---|---|
Infection present | Infection absent | ||
Positive | TP = 33 (0.05769) | FP = 22 (0.03846) | (TP + FP) = 55 (0.09615) |
Negative | FN = 62 (0.10839) | TN = 455 (0.79545) | (FN + TN) = 517 (0.90385) |
Total | (TP + FN) = 95 (0.1669) | (FP + TN) = 477 (0.8339) | N = 572 (1.0, approx.) |
Test statistic | Formula | Value | 95% CI |
---|---|---|---|
Prevalence or a priori probability | (TP + FN)/N | 0.166 | 0.014–0.406 |
Sensitivity (true positive rate) | TP/(TP + FN) | 0.347 | 0.0648–0.5352 |
Specificity (true negative rate) | TN/(FP + TN) | 0.954 | 0.9012–1.0 |
Diagnostic accuracy | (TP + TN)/Na | 0.853 | 0.5944–1.0 |
Positive predictivity | TP/(TP + FP) | 0.6 | 0.248–1.0 |
Negative predictivity | TN/(FN + TN) | 0.88 | 0.6144–1.0 |
False positive rate | FP/(FP + TN) = (1 − specificity) | 0.046 | 0.0008–0.0792 |
False negative rate | FN/(TP + FN) = (1 − sensitivity) | 0.652 | 0.4648–0.9352 |
Positive likelihood ratio | Sensitivity/(1 − specificity) | 7.543 | 0.464–17.556 |
Negative likelihood ratio | (1 − sensitivity)/specificity | 0.685 | 0.524–0.916 |
A posteriori probability | P(E1|E ) | 0.6614 | 0.562–0.758 |
Area under the ROC curve or AUC (a posteriori probability) | 0.62 | 0.473–0.767 |
Population fraction | Prevalence | Sensitivity | Specificity | Posteriori probability |
---|---|---|---|---|
100 | 0.17 | 0.35 | 0.02 | 0.612 |
100 | 0.37 | 0.22 | 0.03 | 0.638 |
100 | 0.33 | 0.12 | 1.0 | 0.6 |
100 | 0.10 | 0.4 | 0.06 | 0.714 |
100 | 0.15 | 0.47 | 0.09 | 0.706 |
72 | 0.111 | 0.25 | 0.03 | 0.692 |
Mean ± SD | 0.23 ± 0.12 | 0.30 ± 0.13 | 0.21 ± 0.39 | 0.66 ± 0.05 |
TP = 33 samples were
CI = confidence interval; FN = false negative; FP = false positive; TN = true negative; TP = true positive.