The ability to measure the quality of health care is important for efforts to improve care. One common way to measure the quality of health care provided by doctors is to review what the doctor writes in the medical chart. This is easy to do but is often inaccurate because doctors do not always write down everything they think about or do. A second way uses standardized patients; these are people who are trained to act like patients and observe whether the doctor asks the right questions, examines the most important parts of the body, and orders the right tests and treatments. Standardized patients provide very accurate measures of quality but are expensive to use. A third method, clinical vignettes, might solve some of these problems. With clinical vignettes, doctors are asked questions about what they would ask or do for a hypothetical patient. Doctors' responses to the questions might provide information similar to that provided by standardized patients at a cheaper cost. However, the accuracy of clinical vignettes for measuring quality needs to be determined.