Sensitivity and specificity

Sensitivity and specificity

1. Sensitivity & Specificity (Validity) By Mohammadi M. Master of Science (Medical Physics) Department of Medical Physics, KUMS

2. Sensitivity & Specificity (Validity) Measure how ‘good’ a test is at detecting binary features of interest (disease/no disease)

3. Terms True positive: Sick people correctly identified as sick False positive: Healthy people incorrectly identified as sick True negative: Healthy people correctly identified as healthy False negative: Sick people incorrectly identified as healthy

4. Sensitivity & Specificity Sensitivity = P (Test+ | Disease+) Specificity = P (Test- | Disease-)

5. Sensitivity & Specificity  

6. Example There are 100 people with 30 having disease A A test designed to identify who has the disease and who does not We want to evaluate how good the test is

7. Sensitivity & Specificity Disease + Disease - Total Test + 25 2 27 Test - 5 68 73 Total 30 70 100

8. Sensitivity & Specificity 25/30 sensitivity 68/70 specificity Disease + Disease - Total Test + 25 2 27 Test - 5 68 73 Total 30 70 100