February, 2003
© 2000, 2001, 2003 Scott S. Emerson, M.D., Ph.D.
Diagnostic Testing: 2
Sensitivity and Specificity
We most often characterize the sensitivity and specificity of a diagnostic test
Sensitivity of test: Probability of positive in diseased
·Sample a cohort of subjects with the disease
·Estimate the proportion who have a positive test result: Pr ( + | D )
·
Specificity of test: Probability of negative in healthy
·Sample a cohort of healthy subjects
·Estimate the proportion who have a negative test result: Pr( - | H )