The sensitivity of a diagnostic test procedure represents the percentage of diseased patients where the relevant medical condition was correctly diagnosed using the test, showing a positive test result. It is defined as the quotient of true positive test results and the sum of true positive and false negative test results. The higher the sensitivity of a test, the more reliable it recognizes the illness.
The specificity of a diagnostic procedure shows the probability that healthy patients, who do not suffer from the relevant disease, are in fact diagnosed as healthy.
It is defined as the quotient of true negative test results and the sum of false positive and true negative test results – in other words all test results where in fact there was no underlying disease.