Profile: Dr. Black is a practicing radiologist with expertise in the evaluation of screening and diagnostic testing. He has demonstrated how advances in diagnostic imaging distort the clinician's perception of the prevalence of disease, its natural history, and its response to medical intervention. He has also studied the public's perception of medical risks and benefits and shown that women 40-49 years of age substantially overestimate their risks of developing and dying from breast cancer. More recently, Dr. Black developed a mathematical method for estimating rates of disease progression from its stage distribution at autopsy and age-specific mortality rates. These estimates are important for making decisions about screening and diagnostic testing and understanding their effects.