SOON AFTERRENELAENNEC INVENTED THE STETHOSCOPE in1816, itwasmetwith“suspicionanddistrust . . . by those who were practicing medicine when it was introduced.” As late as the 1850s, skeptics described the new diagnostic aid as “a dangerous instrument.” While most agree that health care technology has advanced physicians’ ability to improve their patients’ health and quality of life, there has been considerable disagreement about which technologies to use, how much is too much, and whether the technologies clinicians use are providing value for the money spent. In 1827, a commentator on the stethoscope wrote, “The extent of its usefulness is, as yet, far from being ascertained,” and most new technologies since then have been greeted by similar initial doubts. These questions are particularly relevant today, in a US health care system dominated by intense competition among clinicians and organizations vying for a greater share of the market, whether for hospital beds or ambulatory services, drugs, or devices. The promise and potential, but also the doubts and skepticism, apply not only to expensive hightechnology devices, such as magnetic resonance imaging, but also to “little ticket” technologies, such as chest x-ray examinations and prostate-specific antigen testing. Competition can lead to pressure to reduce prices that will benefit purchasers, but also to efforts to enhance quality that will benefit patients. Competition can also lead to a desire to offer more technology, even after its application has been extended to the point of misuse or overuse. Competition can lead to efficiency, but also to excess supply when each competitor feels the need to have the latest technology. Hightech health care is big business. In the guise of informing the public, billboards and the sides of municipal buses are filled with advertisements for hospitals, clinics, or drug companies that tout the use of the newest laser, scanner, or drug. Sometimes, but rarely, these advertisements also inform, but more often they are aimed at achieving name recognition, hardly a giant step toward empowering consumers with better information about the options available to them. At the same time, the US health care system is under pressure to reduce costs and to enhance the value for money in health care. This paradox—the proliferation of new, sometimes expensive technologies in a period of constrained health care spending—has spurred demand for more of the information that decision makers need to make critical decisions that affect both patients’ lives and the bottom line. Different decision makers use information in different ways. Purchasers seek accountability and value for the money they spend for health care services. Health plans need information to guide their coverage of procedures and services. Hospitals and other facilities scrutinize capital investments as they face lower payments under per-case and capitated arrangements. Patients, who now have unprecedented access to information demand services that they have seen or read about. Public policymakers need to know about the effectiveness and efficiency of health care technology to make informed coverage decisions and set sound regulations. Physicians need information to mediate between competing interests, recognizing that they should be prudent with resources but responsive to their patients. The goal of those who develop and provide medical technology and who want to appeal to these decision makers should be to provide value for money. The challenge, then, is to create a health care system that recognizes value, rewards better outcomes, and encourages efficient use of limited resources. The motive for those espousing technological advances should not be name recognition from billboards. It should be the success that comes from offering a service or a product that delivers better health—in short, to answer the modern-day heirs of the 19th-century skeptics who wanted more information about the new stethoscope, about “the extent of its usefulness.” Medical advances have resulted in a constant stream of new technologies: diagnostic tests such as densitometry for osteoporosis and genetic testing for BRCA and procedures such as fetal surgery for neural tube defects. Some may enhance the quality of life, others may save lives, and still others may save money. But which are which? In many cases, new and old technologies exist side by side. Without evidence about the likely outcomes of these services, how can anyone know which technology is more effective and better, or whether more than 1 service should be provided? Older technologies often continue to be used when better technologies are available. One study showed how new