Sensitivity and Specificity
Predictive Values - NPV
Negative Predictive Value (NPV)
The negative predictive value (NPV) is the probability that your negative findings for your diagnostic test are correct. In this situation, the NPV is the probability that your identification of a normal (non-enlarged) thyroid is correct. In order to calculate NPV you will need to know the number of true negatives identified by your test, divided by all patients who had a negative test.
| Ultrasound (gold standard) | Total | ||
| Enlarged (+) | Not Enlarged (-) | ||
| Physical Examination | |||
| Enlarged (+) | 30 | 20 | 50 |
| Not Enlarged (-) | 10 | 40 | 50 |
| Total | 40 | 60 | 100 |
Multi-choiceCalculate the NPV for your diagnostic test. Which of the following is the correct NPV?
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80%
| |
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20%
| |
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40%
| |
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25%
|