School of Nursing and Academic Division of Midwifery

RLO: Positive and Negative Predictive Value of Diagnostic Tests

Introduction
Tests
False results
Prediction table
Using PPV and NPV
Assessment
Feedback
Resources

False results

For most tests a negative result is not always obtained when there is no disease. Some patients will have a positive result, even if no disease is present. These are therefore, false positives, as the test is incorrect.

Equally for most tests a positive result is not always obtained when there is disease. Some cases have a negative result, even if disease is present. These are therefore, false negatives, as the test is incorrect.

Positive test results are a sum of the true positive and false positive results.

Negative test results are a sum of the true negative and false negative results.

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