In medicine and medical statistics, the gold standard, criterion standard,[1] or reference standard[2] is the diagnostic test or benchmark that is the best available under reasonable conditions.[3] It is the test against which new tests are compared to gauge their validity, and it is used to evaluate the efficacy of treatments.[1]
The meaning of "gold standard" may differ between practical medicine and the statistical ideal. With some medical conditions, only an autopsy can guarantee diagnostic certainty. In these cases, the gold standard test is the best test that keeps the patient alive, and even gold standard tests can require follow-up to confirm or refute the diagnosis.[4]