Giving diagnostic tests to “normal” individuals or a population in order to detect diseases. The tests employed include examinations of the blood and urine, x-rays, blood pressure measurements, height and weight, questionnaires, and vision and hearing testing. Screening may be employed for detection of a single problem, such as hypertension (high blood pressure) or drug usage, or it may be a “broad spectrum” screening for “anything abnormal” which can be suspected by using a battery of tests. The latter approach is called multiphasic screening.