ABSTRACT
Clinical and laboratory tests are often used in medicine to help establish a diagnosis. Clinicians need to know how accurate their tests are in diagnosing the true disease status of the patient. For example, how often does an abnormal cervical smear (positive test) indicate that the patient has neoplasia of the cervix (positive disease) and how often does a normal cervical smear (negative test) indicate that the patient does not have neoplasia of the cervix (negative disease)? Table 1 illustrates the relationship between these possibilities.
