All::Clinical Science::Statistics::Sensitivity and Specificity
Intro
What is meant by Sensitivity of a test?
Proportion of patients with the condition who have a positive test result
How is Sensitivity calculated?
TP / (TP + FN)
What is meant by Specificity of a test?
Proportion of patients without the condition who have a negative test result
How is Specificity calculated?
TN / (TN + FP)
What is meant by a tests Positive predictive value?
The chance that the patient has the condition if the diagnostic test is positive
How do you calculate Positive predictive value?
TP / (TP + FP)
What is meant by a tests Negative predictive value?
The chance that the patient does not have the condition if the diagnostic test is negative
How do you calculate Negative predictive value?
TN / (TN + FN)
What is meant by a tests Likelihood ratio for a positive test result?
How much the odds of the disease increase when a test is positive
How do you calculate a Likelihood ratio for a positive test result?
sensitivity / (1 - specificity)
What is meant by a tests Likelihood ratio for a negative test result?
How much the odds of the disease decrease when a test is negative
How do you calculate a Likelihood ratio for a negative test result?
(1 - sensitivity) / specificity