A tool designed to determine the probability that an individual with a negative test result truly does not have the condition being tested for. For instance, if a screening test for a particular disease yields a negative result, this instrument calculates the likelihood that the individual is actually free of that disease, taking into account the prevalence of the disease in the population and the test’s sensitivity and specificity.
This calculation offers valuable insights in clinical settings by helping to interpret the meaning of negative test outcomes. It is particularly useful when assessing the reliability of a test in a specific population, as it considers both the test’s accuracy and the likelihood of the disease being present. Its development marked an improvement in diagnostic testing, emphasizing the importance of context in interpreting results beyond solely relying on test characteristics.
