Statistics

Question 1

Define and give formula for:

-Sensitivity
-Specificity
-Positive predictive value
-Negative predictive value

(August 2022)

Answer 1

Sensitivity: ability of a test to identify patients with a condition. Calculated by dividing the number of true positives by the number of people with a condition

Specificity: ability of a test to correctly identify individuals who do not have a condition. Taken by dividing the number of true negatives by the number of people without a condition

PPV: proportion of individuals with a positive test result who have a condition. Divide the number of true positive test results by total number of positive test results. Increases with increased disease prevalence

NPV: proportion of individuals with a negative test result who do not have a condition. Divide the number of true negative test results by the total number of negative test results. Decreases with increased disease prevalence.