**Q: **What are the 4 possible results of diagnostic testing?
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**A: **1. True positive: Test + & disease +
2. True negative: Test - & disease -
3. False positive: Test + & disease -
4. False negative: Test - & disease +

**Q: **A diagnostic test has a sensitivity of 80%, a specificity of 90%, a PPV of 60%, and an NPV of 95%. Your patient's test result comes back negative. What is the probability that they do not have the disease?
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**A: **95%. This is the NPV, the probability of not having disease after testing negative.

**Q: **A diagnostic test has a sensitivity of 80%, a specificity of 90%, a PPV of 60%, and an NPV of 95%. What is the probability that your patient will test positive if he has the disease?
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**A: **80%. This is the sensitivity, the probability of a positive test result in patient with disease.

**Q: **A diagnostic test has a sensitivity of 80%, a specificity of 90%, a PPV of 60%, and an NPV of 95%. What is the probability that your patient will test negative if he doesn't have the disease?
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**A: **90%. This is the specificity, the probability of a negative test result in the absence of disease.

**Q: **A diagnostic test has a sensitivity of 80%, a specificity of 90%, a PPV of 60%, and an NPV of 95%. What is the probability that your patient will test positive if he has the disease?
show answer

**A: **60%. This is the PPV, the probability of having disease after testing positive.