2.Physicians rely increasingly on a wide array of laboratory tests to solve clinical problems. However, laboratory data do not relieve the physician from the responsibility of carefully observing the patient. It is essential to appreciate the limitations of diagnostic tests. They often gain an aura of certainty regardless of the fallibility of the tests themselves, the instruments used in the tests, and the individuals performing the tests. Physicians must weigh the expense involved in laboratory procedures against the value of the information these procedures are likely to provide.(九分)