Sensitivity and Specificity - a must know




Sensitivity: The ability of finding people with disease who have a positive test result.

Sensitivity = true positives / (true positives + false negatives)

Specificity: The ability of finding people free of a disease who have a negative test.

Specificity = true negatives / (true negatives + false positives)

Positive Predictive Value (PPV): The percentage of people with a positive test result who actually have the disease.

Positive predictive value = true positives / (true positives + false positives) see figure

Negative Predictive Value (NPV): The percentage of people with a negative test who do NOT have the disease.

Negative predictive value = true negatives / (true negatives + false negatives)

3 comments:

  1. Thanks that is an excellent summary

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  2. What does the dark pink area between FP and TP represent ?

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  3. It is FP. both the light and dark pink areas represent false positives.

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